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Critical VMware vCenter RCE flaw exploited for reverse SSH access

Cybersecurity researchers have attributed the exploitation of a newly patched security flaw in Broadcom VMware vCenter to a suspected China-nexus advanced persistent threat (APT). The attacks involve the exploitation of CVE-2026-59310 (CVSS score: 9.8), a severe directory-traversal vulnerability in the VMware vCenter server that could be weaponized by a malicious actor to execute arbitrary code. A fix for the flaw was released by Broadcom on July 29, 2026. German incident response company QUIRSO assessed with moderate confidence that the exploitation campaign aimed at CVE-2026-59310 is operated by a Chinese-speaking threat actor, likely working in the UTC+08:00 time zone, which is predominantly used in Chinese-speaking regions. "This assessment is based on the convergence of…

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Suspected China-Nexus Actor Exploits VMware vCenter Flaw, Deploys Babuk-Derived Ransomware
Cybersecurity researchers have attributed the exploitation of a newly patched security flaw in Broadcom VMware vCenter to a suspected China-nexus advanced persistent threat (APT). The attacks involve the exploitation of CVE-2026-59310 (CVSS score: 9.8), a severe directory-traversal vulnerability in the VMware vCenter server that could be weaponized by a malicious actor to execute arbitrary code. A fix for the flaw was released by Broadcom on July 29, 2026. German incident response company QUIRSO assessed with moderate confidence that the exploitation campaign aimed at CVE-2026-59310 is operated by a Chinese-speaking threat actor, likely working in the UTC+08:00 time zone, which is predominantly used in Chinese-speaking regions. "This assessment is based on the convergence of Chinese-language artifacts in attacker-created scripts, apparent reuse of research from a Chinese security publication, repeated operational use of Chinese-language tools and management software, victimology excluding mainland China, and activity patterns compatible with UTC+08:00 working hours," QUIRSO researchers Maike Orlikowski, Çağatay Yürekli, and Denis Szadkowski said. The activity, which commenced five calendar days after public disclosure of the flaw, is estimated to have compromised 361 unique victim IP addresses across 47 countries, with most of the infections scattered across Germany (55), the U.S. (41), Turkey (38), Iran (26), and France (25). Exploitation of CVE-2026-59309 One compromised vCenter Server Appliance analyzed by QUIRSO is said to have been targeted by both CVE-2026-59310 and CVE-2026-59309, an authentication bypass that has also witnessed active scanning efforts. Evidence shows malicious activity consistent with the exploitation of CVE-2026-59309 as early as August 1, 2026, followed by the creation of an administrative account on vCenter. That said, no login events have been observed for the legitimate administrative account that was used to create this new account. The account creation originated from the IP address 146.59.252[.]178 and also involved vSphere discovery via the REST API on August 3 using User-Agent strings like "GoodMoodle-VCFleet/1.0," in an attempt to masquerade it as VMware-related activity. It's worth noting that VCF Fleet is a centralized management capability introduced by Broadcom in VMware Cloud Foundation (VCF) version 9.0 to deploy, scale, patch, and operate multiple VCF instances. It encompasses multiple components, including VCF Operations, VCF Automation, vCenter, NSX Manager, vSphere Cluster, and workload domains. QUIRSO said there is no overlap between this activity and the chain of events involving the abuse of CVE-2026-59310 on the same system starting August 3, adding the newly created "vcenter_admin" administrator account was not used in subsequent phases of the attack. Exploitation of CVE-2026-59310 As for the exploitation of CVE-2026-59310, the first activity involved the cron daemon (aka crond) logging a malformed cron file called "zz-poc59310-syslog.log." In the next step, a curl command (or alternatively a wget command) is executed to retrieve a backdoor from "5.34.177[.]38:9861" and execute it, and then remove the log file. The naming convention of the log file is significant as it is a direct reference to the CVE identifier and that it was a proof-of-concept (PoC) devised after details of the flaw became public knowledge. "The '-syslog.log' suffix also mirrors the vCSA remote syslog file naming convention, but the file appears under /etc/cron.d rather than the configured syslog output directory," QUIRSO explained. "This suggests that the vCSA syslog server was abused to place files in a privileged execution location. While some files were malformed and not executed by cron, at least one file successfully executed and placed the 'linuxFile' backdoor on the system." The linuxFile implant is designed to provide remote command execution capabilities to the attacker. It establishes a connection to its controller over a WebSocket channel to receive instructions, executes them through /bin/sh, and transmits the results back to the attacker. "The C2 [command-and-control] address is XOR-obfuscated and decoded at run-time, while communications are protected using the malware's own application-layer cryptography despite using an unencrypted ws:// transport," Szadkowski told The Hacker News via email. "It also automatically reconnects on failure and contains routines for establishing persistence through systemd and cron." The threat actor behind the operation also relied extensively on cron to execute malicious payloads, including to fetch and run a shell script ("esxi.sh") from the IP address "185.144.28[.]120:3232." The shell script then serves as a downloader and persistence installer for an architecture-specific reverse SSH ("reverse_ssh") binary that's retrieved from the same infrastructure. Other cron jobs related to creating staging directories, downloading executables, changing their permissions, and running them, while referencing servers at "192.255.141[.]13:8080" and "5.34.176[.]100:5244." In what appears to be an operational security blunder, the latter has been found to expose the reverse SSH binaries toolset via an AList directory listing. A brief description of some of the various actions carried out by the threat actor is as follows - Deploying "linuxFile" (aka systemlog or linux_x86), which connects to "ws://intel.se9ly9upbhay.shop:8080/ws" and establishes persistence via a systemd service. Setting three cronjobs impersonating legitimate VMware services: vmware-vpxd-stats-* (facilitates an SSH-based remote access channel by adding the attacker's SSH public key to the authorized keys file), vmware-perf-collect-* (drops a JSP web shell named "vmware-perf-update.jsp"), and vmware-perf-sync-* (drops the same web shell and runs a Base64-encoded script that performs credential access and sets up a new account called "adminuser," which is then added to the vSphere SSO Administrators group. Creating two additional accounts: adding "vcadmin" to vSphere with a Base64-encoded Python script dropped on disk via bash commands run in a cronjob and creating a vSphere admin account via an external LDAP "Add" operation against vCenter's VMware Directory Service (vmdir) from a remote client by using a pre-existing but compromised administrative account. Creating a file named "/etc/sudoers.d/vmware-perf" with a configuration that grants the "perfcharts" service account unrestricted, non-interactive passwordless sudo access to root. Running shell scripts like "/tmp/.vmware-perf-upd.sh" to obtain credentials for vmdir by querying the HKEY_THIS_MACHINE\services\vmdir registry location. If this method fails, it searches for VMware's vmafd Python module and calls GetMachineName(), GetMachinePassword(), and GetDomainName() to get the distinguished name and password associated with the vCenter machine account. The stolen credentials are used to conduct privileged directory modifications, including adding the aforementioned "adminuser" identity to the Administrators group. Using vSphere API to perform discovery operations and "esxi.sh" to deploy the reverse_ssh client. Creating local accounts on the ESXi hosts (e.g., "adminuser") to enable ransomware encryption. Taking steps to evade detection, reduce forensic visibility, and blend into the VMware environment. The attack ultimately paves the way for the deployment of a ransomware on ESXi hosts that encrypts files with the ".babyk" extension, which is typically associated with Babuk-derived ransomware. It's not clear if this was the end goal of the campaign, or if the Babuk-derived payload was "selected opportunistically or even intentionally" to confuse attribution efforts. QUIRSO told the publication it cannot assess at this stage if the ransomware strain was deployed across other compromised systems as the analysis was limited to only one of the infected systems. However, based on the investigation so far, it's suspected that the deployment of the locker may not have been the primary objective of the campaign. Szadkowski likened the deployment to a smokescreen engineered to distract defenders from the main intrusion and thwart analysis by encrypting the ESXi log files, thereby preventing access to telemetry data that could have offered more insights into threat actor activity. "Exploitation of CVE-2026-59310 provided the actor with immediate, non-interactive code execution in a root context on the vCenter Server appliance," the researchers said. "Subsequent commands recorded by CROND were therefore already being executed as root, giving the actor unrestricted access to the underlying VCSA without first having to compromise an unprivileged local account and escalate from it." Update In a follow-up analysis, QUIRSO said it identified a GitHub repository ("pikpak0066/tmpclean") linked to the same threat actor that, at first blush, appears to be a Go-based program to automatically remove old files from Linux temporary directories. The repository was created on August 14, 2026. It carries the description "Automatic /tmp cleaner daemon for Linux (Go)." "We initially discovered the GitHub repository because we observed the attacker setting it up through the link command of the existing reverse_ssh infrastructure we were monitoring," Szadkowski told The Hacker News. "We then analyzed and reverse engineered the binaries published in the repository's releases. This independently confirmed that they were reverse_ssh builds associated with the attacker's infrastructure." Present in the repository is a Linux systemd service that scans the "/tmp" directory and deletes from it any entries, such as files, symlinks, sockets, and others, whose modification time is at least 24 hours old, and repeats it every hour. Given that the majority of the malicious artifacts associated with the intrusions are staged in the "/tmp" location, it's believed that the threat actor may be using the tool as a way to systematically wipe evidence of the intrusion and complicate analysis. What's more, a release version named "tmpclean v3.0.0" has been found to include updated "reverse_ssh" binaries, suggesting an attempt to distribute additional compiled payloads through the GitHub-based vector. It's not clear what drove the threat actor to set up the repository in the first place, although one possibility is that they are actively tracking public disclosure and are attempting to introduce new cleanup mechanisms to fly under the radar. (The story was updated after publication to include additional insights from QUIRSO.)
thehackernews.comAug 17, 2026extracted
Critical VMware vCenter RCE flaw exploited for reverse SSH access
A recently patched critical vulnerability (CVE-2026-59310) in VMware vCenter Syslog Server is being exploited in an active campaign to deploy a reverse SSH tool for persistence and remote access. Compromises have been identified at 361 IP addresses across 47 countries, more than half located in Germany, the U.S., Turkey, Iran, and France. Broadcom disclosed CVE-2026-59310 on July 29 and described it as a critical directory traversal vulnerability in the vCenter Syslog server that could be exploited by an unauthenticated attacker with network access to execute arbitrary code. The vendor provides no workarounds or mitigations and urges system administrators to apply the emergency update and consult the FAQ post for additional information. The following vCenter releases address the security issue: vCenter 9.1: 9.1.0.0300 vCenter 9.0: 9.0.2.0100 vCenter 8.0: 8.0 U3k or 8.0 U2f, depending on the branch VMware vCenter is a centralized management software for controlling, monitoring, and configuring an organization’s VMware virtual infrastructure, including virtual machines, ESXi servers, configurations, and access permissions. The product is a frequent target for its broad control over multiple critical systems. Attackers can use this access for data theft and operational disruptions. According to digital forensics and incident response (DFIR) company QUIRSO, compromised systems started to connect to attacker-controlled infrastructure on August 3, just five days after Broadcom disclosed the flaw and released the emergency patch. The campaign expanded quickly, with 151 new victim IP addresses being observed on August 4. By the next day, the count of victim IPs reached 343. However, QUIRSO notes that it identified a total of 361 victim IPs by August 7. After obtaining access to vulnerable vCenter systems, the attacker deployed the open-source reverse_ssh framework to establish persistence and gain remote access. The reverse SSH connection provides an outbound command-and-control (C2) channel and can also help bypass firewalls or other network security measures. QUIRSO has released a generic YARA rule that detects reverse_ssh client binaries. It should be noted that legitimate use of the tool also triggers the alert. The researchers believe that an advanced persistent threat (APT) actor is behind the exploitation activity, although they provided no evidence to support this and are withholding specific indicators due to ongoing coordination with law enforcement authorities. QUIRSO plans a more detailed follow-up report that covers the attacker’s infrastructure, techniques, persistence, and post-exploitation activity. BleepingComputer has contacted Broadcom for a statement on QUIRSO’s findings, but we have not received a response by publication time. Overall prevention scores can hide what happens after initial access. Once attackers are using valid credentials, prevention drops sharply. The Blue Report 2026 measures defenses technique by technique across 338 million simulations run in customer production environments. Get the report
bleepingcomputer.comAug 13, 2026extracted
Attackers Exploit VMware vCenter Vulnerability to Gain Persistent Remote Access
Threat actors have begun to actively exploit a recently patched critical security flaw in Broadcom VMware vCenter, according to new findings from QUIRSO. The vulnerability in question is CVE-2026-59310 (CVSS score: 9.8), a directory-traversal vulnerability in the VMware vCenter server that a malicious actor with network access can exploit to execute arbitrary code. Patches for the flaw were released by Broadcom late last month. The German cybersecurity company said it discovered the activity following an incident response engagement. The attack chain is said to have exhibited path traversal activity consistent with the flaw, followed by the deployment of a malicious cron job to establish persistence on the host using reverse_ssh, an open-source tool used for setting up SSH connections to threat actor-controlled infrastructure. Compromised systems identified by QUIRSO were found to first establish contact with the attacker's domains on August 3, five days after Broadcom publicly disclosed the flaw. In all, there are as many as 361 unique victim IP addresses located across 47 countries. Most of them are located in Germany, the U.S., Turkey, Iran, and France. "While the attacker might have had prior knowledge of the vulnerability, the strong correlation between the time of disclosure and exploitation suggests the disclosure as the initial starting point for the campaign," QUIRSO added. It's not clear who is behind the exploitation campaign, but it's believed to be the work of a suspected advanced persistent threat (APT) actor. It's worth pointing out that VMware appliances have been a lucrative target for Chinese threat actors like UNC5174, who have weaponized security flaws impacting VMware Tools and VMware vCenter in various espionage campaigns. In April 2025, SentinelOne disclosed details of a China-nexus threat cluster dubbed PurpleHaze that targeted a South Asian government supporting entity with a Windows backdoor called GoReShell, which uses functionalities from the reverse_ssh tool to establish reverse SSH connections to attacker-controlled hosts. The use of reverse_ssh is notable as it allows the attacker to establish an outbound connection to an endpoint under their control, effectively bypassing security controls designed to prevent suspicious inbound requests. "The presence of reverse_ssh should not, by itself, be treated as proof of malicious activity," QUIRSO noted. "In combination with unauthorized installation, unexpected outbound connections or execution on a vulnerable vCenter appliance, however, it is a high-priority indicator requiring investigation." The disclosure comes as Defused Cyber said it's observing a spike in scanning against VMware vCenter that is indicative of potential exploitation efforts targeting CVE-2026-59309 (CVSS score: 9.8). "Our honeypots are logging increased fingerprinting – such as version probes via POST /sdk/ (RetrieveServiceContent) and walks of the /websso SAML SSO flow – coinciding with Broadcom's VMSA-2026-0006 (CVE-2026-59309, unauth auth-bypass in vmdir, CVSS 9.8)," the cybersecurity company said. Denis Szadkowski, COO and co-founder of QUIRSO GmbH, told The Hacker News that there is not enough evidence at this stage to correlate exploitation and scanning efforts using CVE-2026-59309 with the intrusion set or the attacker infrastructure associated with CVE-2026-59310. "What we can say with much higher confidence is that the activity we investigated represents a successful compromise rather than merely exploitation attempts, and the forensic evidence strongly points toward CVE-2026-59310 as the initial access vector," Szadkowski added.
thehackernews.comAug 12, 2026extracted
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Attackers Exploit Third Arista VCO Zero-Day in Four Months
Networking solutions provider Arista Networks on Thursday rolled out patches for an exploited zero-day vulnerability in its centralized management tool VeloCloud Orchestrator (VCO). The critical-severity security defect is tracked as CVE-2026-114625 (CVSS score of 9.9) and is described as a remotely exploitable SQL injection. “VeloCloud Orchestrator (VCO) on-prem has a security issue where this issue may allow a remote attacker to access privileged internal functionality and impact the VCO host,” Arista notes in its advisory. Successful exploitation could impact the confidentiality, integrity, and availability of both VCO and the data it manages. “On an affected system, any authenticated user can gain operator privileges and masquerade as a local ‘superuser operator’ user. This includes access to functionality that is intended for internal use only and which is not intended to be remotely accessible,” the company says. All VCO releases before versions 5.2.3.18, 6.1.3.10, and 6.4.2.12 are affected. Arista has already patched the hosted VCO deployments, but urges users to update their on-premises installations as soon as possible. “This issue was detected by Arista and is known to be actively exploited,” the company says. Arista notes that VCO deployments are exposed by default, and that attackers need access to the VCO web interface and a valid authenticated session, with the lowest built-in tenant role privileges. “There is no configuration that can prevent the exposure,” the company notes. Attacks have been observed originating from two IP addresses, 74.82.197.86 and 38.54.50.151. Administrators should block them, check logs for their presence, and investigate high-request rates, as well as requests with unusual URL-like path components, encoded characters, and references to local or internal services. “If compromise is suspected, operators should preserve VCO web access logs, backend application logs, system logs, database logs, and relevant file-system timestamps before remediation where operationally feasible,” Arista notes. Updating to a fixed VCO release is the recommended remediation action. Until the fixes are deployed, administrators should restrict access to the VCO interface, review recent admin activity, monitor for suspicious access, block outbound ports, and monitor for backdoor daemons and webshells. CVE-2026-114625 is the third exploited zero-day vulnerability Arista patches in VCO in four months, after CVE-2026-16812 in July and CVE-2026-93952 in September. Related: Atlassian Patches 75 Flaws in Data Center and Server Products Related: Signal Vulnerability Lets Malicious Callers Block Hang-Ups Related: Splunk, SolarWinds Release Fresh Security Updates Related: Cisco Patches 34 Vulnerabilities Across Multiple Products
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Oct 29, 2026
Worm armed 42 GitHub repos by hiding a payload too big to fail
Some attacks take real skill. Others just need someone to leave a door open. This week has both. Exposed passwords, old bugs still getting exploited, and trusted software doing things it shouldn't. There's a strange mix of clever tricks and careless mistakes. Hackers are borrowing trust from familiar apps, websites, and AI tools. Some are using AI to speed things up. Others are leaving their own attack files exposed. Not exactly careful work. Different stories, familiar weak spots. Here's what showed up this week. The threats change every week. Subscribe, and we’ll alert you when each new ThreatsDay Bulletin is out. PHP2Shell attacks persist WordPress security company Wordefence said it's not aware of any WordPress site compromised through PHP2Shell (CVE-2026-109618 and CVE-2026-109619) as of October 28, 2026. "We continue to see PHP2Shell-related requests across the more than 5 million sites we protect," it said. "Those requests show ongoing scanning and exploitation attempts; they do not show whether an attempt succeeded. Our site-cleaning and incident response teams have not handled a WordPress compromise attributed to these vulnerabilities." 40,573 secrets exposed Hudson Rock's investigation into the FortiBleed credential harvesting campaign has uncovered 975 newly identified domains and 40,573 exposed secrets, including 37,076 local-user records and 1,576 Active Directory LDAP bind records. The data comes from newly obtained 1,703 FortiGate source files associated with 1,689 host identifiers. "The configuration material dates to around February 2026, earlier than the likely May/June material examined in the first investigation," Hudson Rock said. The latest discovery has been codenamed FortiBleed 2.0. Institutional DNS hijacked Threat actors have used domain shadowing to place illegal gambling content beneath legitimate school and government domains in two unrelated operations. "In both cases, an unauthorized party appears to have gained access to DNS administration and created records that the original domain owners may not have noticed," Infoblox said. "Because the resulting hostnames sat within established institutional namespaces, they provided especially useful infrastructure for search-engine optimization (SEO) and traffic acquisition." One cluster, linked to a threat actor called Hidden Hawk, has been found to add individual CNAME records that mapped institutional hostnames to gambling pages hosted largely on Cloudflare Pages. The second campaign exploiting an Indian government domain "delegated entire subzones to third-party authoritative nameservers and used a wildcard, allowing many hostnames to be managed outside the victim's DNS environment." Put differently, the unauthorized DNS access creates new institutional hostnames, which resolve to infrastructure serving illegal gambling doorway pages. The pages also leverage the established reputation of school and government namespaces to ensure that the malicious URLs show up prominently in search engine results. AI banking credential warning Bank of America is reminding customers not to share banking credentials with AI agents. In an email blast to customers titled "Protecting your finances in the AI World," the financial institution urged customers to never share their username and password with another person or an outside service, "including an AI-enabled tool or agent that offers to act on your behalf." Android tightens contact access Google has announced that an upcoming Android release will no longer be able to directly write to contacts with the WRITE_CONTACTS permission. "Instead, you can use the standard contact intents (ACTION_INSERT, ACTION_EDIT, and ACTION_INSERT_OR_EDIT)," Google said. "Currently, if your app needs to save even one contact, you might be requesting WRITE_CONTACTS. But that permission grants broad access, allowing an app to make widespread changes to contacts across the device in the background, even without user interaction. Most apps don’t need such broad permission." 26,400 live credentials exposed A scan of 7.25 million public repositories on Gitee, China's largest indigenous Git hosting platform, has uncovered 26,400 unique verified-live credentials, including an active organization-admin credential for a major enterprise AI platform and thousands of live cloud provider access keys, independent security researcher Ben Zimmermann said. Critical Fortinet fixes released Fortinet has released a "coordinated set of security updates for FortiOS, FortiManager, and FortiAnalyzer" to address critical and high-severity flaws that were flagged using an AI-assisted vulnerability discovery approach. Details of the issues are being kept under wraps until November 10, 2026. With Fortinet devices becoming a favorite target for attackers, it's essential that users move quickly to apply the fixes. Zero-permission token theft Details have emerged about a now-patched flaw in Microsoft Authenticator (CVE-2026-80097 aka AuthMask) that could be exploited by installing and running a malicious application on an affected Android device and convincing the user to complete an authentication flow in the app by claiming to be a trusted app and getting the corresponding tokens. The flaw could be exploited to take over work accounts without requiring additional permissions. "Successful exploitation could allow the attacker to obtain authentication tokens and access resources as the affected user," Microsoft said. According to Enclave, "an unprivileged Android app with zero permissions could impersonate any installed Microsoft first-party app and have the Microsoft Authenticator broker hand it that app's tokens. The setup is a device with Authenticator installed and one work account signed into it." 32 fake AI bots hunt secrets Attackers are disguising themselves as AI agents to steal credentials. Cequence said it has tracked a single actor running AI agent impersonation at scale by posing as about 32 different AI bots, including ChatGPT, Claude, and Perplexity, while searching for passwords, API keys, and cloud credentials. "The malicious scanner runs from a major cloud provider and rotates through about 32 AI bot identities, spanning crawlers and assistants from OpenAI, Anthropic, Meta, Perplexity, and others," Will Glazier said. "It ignores web pages and requests files that commonly store secrets, including .env configuration files, cloud credential files, private SSH keys, and server environment data, working from a list of roughly 90 file paths. Each address sends a short burst of 50 to 190 requests in about eight seconds and then moves on. The scanner works through targets one at a time, around the clock, and first sends random nonsense paths to find websites that answer every request, a common scanning technique. It hit organizations in financial services, retail, telecommunications, energy, and software, and stayed active from at least late September through late October." China-linked network intrusion The U.S. Embassy in Fiji has revealed that hackers linked to China broke into a regional organization based in Suva between July and August 2026. "Hackers with links to China maintained access to the organization's network over several days," it said. The embassy did not name the threat actor. Nor did it disclose what data the attackers may have accessed. Camera software weaponized Attackers have been breaking into enterprise networks via camera management software, according to new research from security firm Huntress, which observed multiple incidents in September and October 2026 and traced them back to a compromised application. Source code artifacts point to a Korean company selling analog and IP cameras and digital and network video recorders. The activity abuses the legitimate "WpcMon.exe" binary to sideload DLLs that establish outbound connections to a remote server. "This activity demonstrates how attackers can blend malicious code with trusted Windows components to evade detection," Huntress said. 68 GB government data breach In a major operational security blunder, an unknown threat actor stole 68 GB from a Philippine government agency, maintained a detailed log of the transfer, then left that log open on the internet at 13.163.205[.]35:80. "The copy finished in under 24 minutes on September 6, 2026," Hunt.io said. "The transfer log records 27 SQL Server backups whose filenames correspond to the case-management systems of a Philippine overseas-employment and migrant-worker administration. Beside the log sat the operator's toolkit, a rebranded GodPotato build, a PowerShell stager, two payloads and a full Impacket environment." AI model data exfiltration concerns Canadian AI company Cohere has claimed that it caught Alibaba's Qwen3.8-Flash-Next model unsuccessfully attempting to send data to China from its evaluation sandbox as part of a prompt instructing the LLM to detect malicious file download and execution by monitoring for curl processes downloading bash scripts to /tmp followed by bash execution. "Asked to write a defensive detection rule, Qwen3.8-Flash-Next ignored instructions and inventoried the machine it was running on and then tried to upload a probe file to an Alibaba Cloud storage bucket in Beijing," Cohere said. "We cannot answer whether this is deliberate or a leftover glitch from training." Cohere has also released a dataset containing the model trace and corresponding raw token IDs in connection with the behavior. "The exact output is not guaranteed all the time, and many trials may be required to reproduce the behavior," Cohere said, adding "there are similarly unexpected URLs that the model also tends to output, most containing aliyunc." However, the findings have also led to social media chatter that the company is resorting to geopolitical fearmongering and that they are an attempt to clamp down on open-weights models. Post-quantum migration roadmap The U.S. National Institute of Standards and Technology (NIST) has released guidelines that detail the timelines for transitioning away from quantum-vulnerable algorithms to quantum-resistant standards. "The report describes different use cases and says why one migration might take longer than another," said NIST mathematician Dustin Moody, who heads the PQC standardization project. "We understand there's not one strategy that fits all use cases, and we want to help people handle their migration while staying abreast of what's changing." AI-powered ransomware operation exposed SOCRadar has uncovered the live workspace (i.e., open directory) of a threat actor tied to the n0n ransomware group, which exposed the operation's full workflow as of September 2026. The directory at 185.157.161[.]148 includes an AI coding agent configured with about 150 models to produce hundreds of attack scripts, with more than $7,216 in usage costs. "Entry points included a credential stuffing campaign against 305 FortiGate SSL-VPN devices, exposed AWS keys, weak RDP/WinRM credentials, and compromised hosting management portals," SOCRadar said. At least 23 organizations across 14 countries are said to have been identified in the workspace, including a U.S. sports retailer, a cloud provider, a teachers’ union, a Venezuelan ISP, an Argentine ministry and a pharmaceutical subsidiary. Government AI access restricted The Swedish government has barred employees from accessing browser-based versions of ChatGPT or Claude on their work computers over security concerns relating to the processing of sensitive data. "Officials were concerned that entering sensitive information into these models without an agreement setting out how to protect and secure the data could lead to it being fed into the model and stored for training," Euro News reported. 42 repositories hijacked JFrog and SafeDep have uncovered a campaign in which threat actors hijacked third-party 42 GitHub repositories across 11 owners to deploy payload blobs large enough "to evade the GitHub search and API paths normally used to find this kind of compromise." JFrog said, "The repositories contain execution hooks for AI coding assistants and IDEs, plus 12.9 to 13.7 MB polymorphic wrappers that all decode to the same hidden CI-publisher payload." The activity is assessed to be related to a Miasma-family npm worm propagated under various packages ending with "testmetest." According to SafeDep, the worm "shares code with Miasma 'Phantom Gyp' from June 2026 and adds the token-revocation wiper from Mini Shai-Hulud. The malicious versions steal credentials, spread to other packages and repositories, and install a wiper that deletes the home directory when the victim revokes the stolen GitHub token." Unsuspecting developers who installed the packages had their data stolen and repositories compromised with malicious code to produce further malicious testmetest releases and run shellpanel workflows targeting cPanel systems through CVE-2026-41940, overlapping with a prior campaign detailed by Socket in July 2026. Android banking malware-as-a-service A new Android malware operation called MR ROBOT is targeting customers of Indian banks and transforming banking fraud into a subscription business, with cybercriminals renting customized banking trojans to steal OTPs, card details, UPI PINs and credentials while secretly forwarding calls to bypass security checks. "It is not a single-actor campaign but a rented crimeware platform: a master operator leases access to affiliates, who use a Telegram bot ('APK Shield) and a web control panel (v7.0) to build personalized banking trojans on demand and distribute them through fake Play-Store-style pages and messaging-app lures," CloudSEK said. The kit impersonates around 36 lure apps, including banks, utility providers, and government services. One affiliate is estimated to have intercepted 5407 text messages from 153 infected devices. MDM platforms abused for remote access Threat actors are abusing legitimate mobile device management (MDM) platforms, like Hexnode and Rippling, by using social engineering to enroll devices or install management agents, per Huntress. "Once established, MDM provides a trusted, privileged path for malicious activity, such as deploying rogue RMM tools and maintaining remote access," it said. Critical Gotenberg RCE exploited Threat actors are exploiting CVE-2026-42589 (CVSS score: 9.8), a critical remote code execution flaw in Gotenberg, to deliver a Go-based reverse shell called "cache_base." The flaw was patched in May 2026. According to VulnCheck, the activity originated from a residential Japanese IP address in early October 2026. "The execution flow is straightforward: acquire a lock, collect host information, connect to C2, register the victim, and open a shell," VulnCheck said. Over the past 30 days, the vulnerability has recorded 1,358 exploitation events from 128 unique source IP addresses. Discord discussions go public Discord has announced it will allow search engines to index discussions in Discoverable Servers and make them accessible on the web to users outside the platform without an account or invitation, starting mid-December 2026. "Discussions in Discoverable Servers will soon be easier to find when you search the web, so you can find the answer you're looking for and step straight into the conversation on Discord," it said. The changes apply only to Discoverable Servers and do not extend to private servers and direct messages. 800+ ransomware victims claimed The Gentlemen ransomware operation has claimed more than 800 victims across multiple regions and sectors, with most attacks targeting organizations in the U.S. and Europe. "The group supports multiple platforms, with ransomware variants targeting Windows, Linux, NAS, and BSD systems, allowing its affiliates to target a broad range of enterprise environments," Acronis said. "The group's operations include the use of EDR-killing tools. In a recent incident, a custom dropper was observed deploying vulnerable Safetica ProcessMonitorDriver [CVE-2025-70795] and Lenovo BootRepair.sys drivers to terminate security processes." AI model loading RCE risk Pillar Security has disclosed an arbitrary-code-execution vulnerability in Unsloth's core model-loading path (CVE-2026-93348, CVSS score: 8.6). It has been fixed in unsloth_zoo 2026.8.14. "An attacker-controlled model configuration could cause Python code to execute during loading," researcher Ariel Fogel said. "The affected code ran inside the model-loading process, with access to whatever that process could read, modify, or authenticate to. In an AI development environment, that can include proprietary datasets, model artifacts, Hugging Face tokens, and cloud credentials. Exploitation required an affected loading path to process an attacker-controlled configuration." Unauthenticated root-level RCE XBOW said it identified an unauthenticated, critical-severity remote code execution bug in a public web application belonging to the U.S. Election Assistance Commission (EAC). "The vulnerable application was a resource/logistics calculator, not a voting machine or voter registration system," XBOW researcher Ariel Walter Garcia said. "The flaw allowed an unauthenticated attacker to execute code as root inside the backend container, with access to locally protected resources and outbound network connectivity, a privileged foothold reachable via a crafted unauthenticated web request." Session-hijacking RAT emerges A new remote access trojan called DarkCore comes with a dedicated browser that could let attackers access Gmail, WhatsApp, and MediaFire accounts using stolen sessions, while giving the impression that the activity is originating from the victim's own IP address. DarkCore was first advertised on cybercrime forums in August 2026. "The seller describes a browser that reuses those sessions to access work mailboxes, instant messaging apps, cloud storage and other services through the infected machine's IP address," BlackFog said. "The purpose is to make the access look like legitimate activity from the user." AI-powered malware framework Cisco Talos has disclosed details of a new AI-integrated command-and-control (C2) framework called NIK C2. The implant features surveillance, theft, lateral movement, and evasion capabilities, including credential dumping, RDP session hijacking, process hollowing, and a C2-driven screen lock ransomware module. "NIK C2 contains a Windows implant, using which, an actor can dump credentials, stream the victim's keystrokes to collect the targeted victim's sensitive data, and instruct an integrated AI model to analyze the harvested data, all within the compromised session," Talos said. "In this framework, the actor has abused the OpenAI Chat Completions application programming interface (API), which is an HTTP endpoint that enables ChatGPT-style conversations programmatically. In addition to the features that enable theft, an actor can also deploy desktop screen-locking ransomware via the NIK C2 implant onto the victim machine, leading to a ransom demand in Bitcoin or USDT cryptocurrencies." Three different versions of the malware have been identified to date since August 12, 2026. Talos said NIK C2 alters adversary tradecraft by collapsing collection and exploitation into a single continuous session. Malicious PDF delivers backdoor A phishing email using a FedEx tax invoice lure and containing a ZIP archive with a PDF has been observed triggering a multi-stage infection process to deliver a previously undocumented variant of the Sirius Backdoor. "The PDF abuses /OpenAction and /Launch objects to trigger an embedded Base64-encoded PowerShell command upon opening," Trellix said. "Execution relies on social engineering to trick the user into approving the PDF reader's security confirmation prompt. The PowerShell stager decrypts and reflectively loads a .NET assembly in memory. This loader performs process hollowing into legitimate Windows processes such as msbuild.exe, svchost.exe, etc., allowing the malware to operate under trusted process contexts." The final payload is SIRIUS, a Microsoft Visual C++ based backdoor with extended remote access capabilities. AI reshapes ransomware economics A new analysis from Flare has revealed that threat actors are building a mixed AI toolkit, combining commercial models with local, open-weight, and jailbroken alternatives, as well as leaning on stolen AI credentials to shift costs to victims. "Where AI can help is with understanding systems, writing tools and troubleshooting. The threat actor still needs access, decisions and a way to obtain payment," Flare said. "If AI helps an affiliate write a working data-export script without hiring a specialist, the affiliate may avoid that specialist’s fee and the wait for their help. AI makes expertise cheaper to obtain only when the cost of using and checking its work is lower than the cost of the specialist help it replaces." Emerging data-extortion threat A recently observed cyber-extortion actor named ScarlettGroup is publicly advertising alleged data compromises and uses negotiation deadlines and threatened disclosures to pressure targeted organizations. The group's dark web site listing includes victims from technology, education, government, and entertainment sectors. "ScarlettGroup demonstrates characteristics associated with financially motivated data-extortion operations, including public victim claims, deadline-based pressure, and underground forum activity," Foresiet said. "Its dedicated leak-site infrastructure and structured disclosure mechanism indicate an organized approach to promoting alleged compromises and exerting reputational pressure." Infostealers evolve into RATs Following its disruption in June 2026 as part of Operation Endgame, StealC has returned four months later as Stadia. "This time it's not a stealer: it's a full remote access trojan," Varonis said. "The RAT's features include hidden desktop control, a live command shell, a file explorer, a process manager and an in-memory loader, with StealC's stealer welded on as one module among six. The actor behind Stadia is working hard to win back original StealC customers: every former StealC customer is offered a free month on the top ($900) tier." The development comes as Moonlock Lab revealed that the Icarus macOS stealer has similarly evolved from a smash-and-grab crypto and data stealer to a malware with remote-access capabilities. The new iteration is called ICMacOS. "The stealer is actively advertised on cybercrime forums by a Russian-speaking actor operating under the handle GlowComa, with feature updates regularly announced via Telegram," SOCRadar said. "GlowComa promotes ICMacOS alongside Icarus ClickFix, a companion panel designed to deliver payloads using malicious copy-and-paste terminal commands. The infection chain relies on initial dropper scripts to detect the host architecture and harvest administrator passwords using fake system dialogs before delivering the primary payload." Another macOS-focused stealer is Aokigahara, which goes beyond browsers, VPN clients, cryptocurrency wallets, FTP/SFTP clients, password managers, and email applications to also target AI applications and development tools. "The stealer collects authentication files, session data, and configuration files associated with Claude, ChatGPT Desktop, Codex, Cursor, Windsurf, GitHub Copilot, Gemini CLI, and other tools," Check Point said. "Stolen AI credentials could offer opportunities for monetization. Usable credentials or session tokens could enable unauthorized access to paid AI services or the resale of compromised accounts." That's the week's mess. Some attacks were clever, some were painfully simple, and a few attackers made life easier for the people investigating them. The common problem? Too much trust in things nobody was watching closely. AI is adding new tricks, but the old ones aren't going anywhere. Stolen credentials, weak access controls, and forgotten bugs still get plenty of work done. New tools, familiar mistakes. The useful part is knowing where those mistakes keep showing up. That's usually where the next problem starts.
6 shared
Oct 30, 2026
Analyzing Sharepoint Exploits (CVE-2025-53770, CVE-2025-53771), (Wed, Jul 23rd)
On July 19–20, 2025, various security companies and national CERTs published alerts about active exploitation of on-premise SharePoint servers. According to the reports, observed attacks did not require authentication, allowed attackers to gain full control over the infected servers, and were performed using an exploit chain of two vulnerabilities: CVE-2025-49704 and CVE-2025-49706, publicly named “ToolShell”. Additionally, on the same dates, Microsoft released out-of-band security patches for the vulnerabilities CVE-2025-53770 and CVE-2025-53771, aimed at addressing the security bypasses of previously issued fixes for CVE-2025-49704 and CVE-2025-49706. The release of the new, “proper” updates has caused confusion about exactly which vulnerabilities attackers are exploiting and whether they are using zero-day exploits. Kaspersky products proactively detected and blocked malicious activity linked to these attacks, which allowed us to gather statistics about the timeframe and spread of this campaign. Our statistics show that widespread exploitation started on July 18, 2025, and attackers targeted servers across the world in Egypt, Jordan, Russia, Vietnam, and Zambia. Entities across multiple sectors were affected: government, finance, manufacturing, forestry, and agriculture. While analyzing all artifacts related to these attacks, which were detected by our products and public information provided by external researchers, we found a dump of a POST request that was claimed to contain the malicious payload used in these attacks. After performing our own analysis, we were able to confirm that this dump indeed contained the malicious payload detected by our technologies, and that sending this single request to an affected SharePoint installation was enough to execute the malicious payload there. Our analysis of the exploit showed that it did rely on vulnerabilities fixed under CVE-2025-49704 and CVE-2025-49706, but by changing just one byte in the request, we were able to bypass those fixes. In this post, we provide detailed information about CVE-2025-49704, CVE-2025-49706, CVE-2025-53770, CVE-2025-53771, and one related vulnerability. Since the exploit code is already published online, is very easy to use, and poses a significant risk, we encourage all organizations to install the necessary updates. The exploit Our research started with an analysis of a POST request dump associated with this wave of attacks on SharePoint servers. We can see that this POST request targets the “/_layouts/15/ToolPane.aspx” endpoint and embeds two parameters: “MSOtlPn_Uri” and “MSOtlPn_DWP”. Looking at the code of ToolPane.aspx, we can see that this file itself does not contain much functionality and most of its code is located in the ToolPane class of the Microsoft.SharePoint.WebPartPages namespace in Microsoft.SharePoint.dll. Looking at this class reveals the code that works with the two parameters present in the exploit. However, accessing this endpoint under normal conditions is not possible without bypassing authentication on the attacked SharePoint server. This is where the first Microsoft SharePoint Server Spoofing Vulnerability CVE-2025-49706 comes into play. CVE-2025-49706 This vulnerability is present in the method PostAuthenticateRequestHandler, in Microsoft.SharePoint.dll. SharePoint requires Internet Information Services (IIS) to be configured in integrated mode. In this mode, the IIS and ASP.NET authentication stages are unified. As a result, the outcome of IIS authentication is not determined until the PostAuthenticateRequest stage, at which point both the ASP.NET and IIS authentication methods have been completed. Therefore, the PostAuthenticateRequestHandler method utilizes a series of flags to track potential authentication violations. A logic bug in this method enables an authentication bypass if the “Referrer” header of the HTTP request is equal to “/_layouts/SignOut.aspx”, “/_layouts/14/SignOut.aspx”, or “/_layouts/15/SignOut.aspx” using case insensitive comparison. The code displayed in the image above handles the sign-out request and is also triggered when the sign-out page is specified as the referrer. When flag6 is set to false and flag7 is set to true, both conditional branches that could potentially throw an “Unauthorized Access” exception are bypassed. On July 8, 2025, Microsoft released an update that addressed this vulnerability by introducing additional checks to detect the usage of the “ToolPane.aspx” endpoint with the sign-out page specified as the referrer. The added check uses case insensitive comparison to verify if the requested path ends with “ToolPane.aspx”. Is it possible to bypass this check, say, by using a different endpoint? Our testing has shown that this check can be easily bypassed. CVE-2025-53771 We were able to successfully bypass the patch for vulnerability CVE-2025-49706 by adding just one byte to the exploit POST request. All that was required to bypass this patch was to add a “/” (slash) to the end of the requested “ToolPane.aspx” path. On July 20, 2025, Microsoft released an update that fixed this bypass as CVE-2025-53771. This fix replaces the “ToolPane.aspx” check to instead check whether the requested path is in the list of paths allowed for use with the sign-out page specified as the referrer. This allowlist includes the following paths: “/_layouts/15/SignOut.aspx”, “/_layouts/15/1033/initstrings.js”, “/_layouts/15/init.js”, “/_layouts/15/theming.js”, “/ScriptResource.axd”, “/_layouts/15/blank.js”, “/ScriptResource.axd”, “/WebResource.axd”, “/_layouts/15/1033/styles/corev15.css”, “/_layouts/15/1033/styles/error.css”, “/_layouts/15/images/favicon.ico”, “/_layouts/15/1033/strings.js”, “/_layouts/15/core.js”, and it can contain additional paths added by the administrator. While testing the CVE-2025-49706 bypass with the July 8, 2025 updates installed on our SharePoint debugging stand, we noticed some strange behavior. Not only did the bypass of CVE-2025-49706 work, but the entire exploit chain did! But wait! Didn’t the attackers use an additional Microsoft SharePoint Remote Code Execution Vulnerability CVE-2025-49704, which was supposed to be fixed in the same update? To understand why the entire exploit chain worked in our case, let’s take a look at the vulnerability CVE-2025-49704 and how it was fixed. CVE-2025-49704 CVE-2025-49704 is an untrusted data deserialization vulnerability that exists due to improper validation of XML content. Looking at the exploit POST request, we can see that it contains two URL encoded parameters: “MSOtlPn_Uri” and “MSOtlPn_DWP”. We can see how they are handled by examining the code of the method GetPartPreviewAndPropertiesFromMarkup in Microsoft.SharePoint.dll. A quick analysis reveals that “MSOtlPn_Uri” is a page URL that might be pointing to an any file in the CONTROLTEMPLATES folder and the parameter “MSOtlPn_DWP” contains something known as WebPart markup. This markup contains special directives that can be used to execute safe controls on a server and has a format very similar to XML. While this “XML” included in the “MSOtlPn_DWP” parameter does not itself contain a vulnerability, it allows attackers to instantiate the ExcelDataSet control from Microsoft.PerformancePoint.Scorecards.Client.dll with CompressedDataTable property set to malicious payload and trigger its processing using DataTable property getter. Looking at the code of the ExcelDataSet’s DataTable property getter in Microsoft.PerformancePoint.Scorecards.Client.dll, we find the method GetObjectFromCompressedBase64String, responsible for deserialization of CompressedDataTable property contents. The data provided as Base64 string is decoded, unzipped, and passed to the BinarySerialization.Deserialize method from Microsoft.SharePoint.dll. Attackers use this method to provide a malicious DataSet whose deserialized content is shown in the image above. It contains an XML with an element of dangerous type "System.Collections.Generic.List1[[System.Data.Services.Internal.ExpandedWrapper2[...], System.Data.Services, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089]]", which allows attackers to execute arbitrary methods with the help of the well-known ExpandedWrapper technique aimed at exploitation of unsafe XML deserialization in applications based on the .NET framework. In fact, this shouldn’t be possible, since BinarySerialization.Deserialize in Microsoft.SharePoint.dll uses a special XmlValidator designed to protect against this technique by checking the types of all elements present in the provided XML and ensuring that they are on the list of allowed types. However, the exploit bypasses this check by placing the ExpandedWrapper object into the list. Now, to find out why the exploit worked on our SharePoint debugging stand with the July 8, 2025 updates installed, let’s take a look at how this vulnerability was fixed. In this patch, Microsoft did not really fix the vulnerability but only mitigated it by adding the new AddExcelDataSetToSafeControls class to the Microsoft.SharePoint.Upgrade namespace. This class contains new code that modifies the web.config file and marks the Microsoft.PerformancePoint.Scorecards.ExcelDataSet control as unsafe. Because SharePoint does not execute this code on its own after installing updates, the only way to achieve the security effect was to manually run a configuration upgrade using the SharePoint Products Configuration Wizard tool. Notably, the security guidance for CVE-2025-49704 does not mention the need for this step, which means at least some SharePoint administrators may skip it. Meanwhile, anyone who installed this update but did not manually perform a configuration upgrade remained vulnerable. CVE-2025-53770 On July 20, 2025, Microsoft released an update with a proper fix for the CVE-2025-49704 vulnerability. This patch introduces an updated XmlValidator that now properly validates element types in XML, preventing exploitation of this vulnerability without requiring a configuration upgrade and, more importantly, addressing the root cause and preventing exploitation of the same vulnerability through controls other than Microsoft.PerformancePoint.Scorecards.ExcelDataSet. CVE-2020-1147 Readers familiar with previous SharePoint exploits might feel that the vulnerability CVE-2025-49704/CVE-2025-53770 and the exploit used by the attackers looks very familiar and very similar to the older .NET Framework, SharePoint Server, and Visual Studio Remote Code Execution Vulnerability CVE-2020-1147. In fact, if we compare the exploit for CVE-2020-1147 and an exploit for CVE-2025-49704/CVE-2025-53770, we can see that they are almost identical. The only difference is that in the exploit for CVE-2025-49704/CVE-2025-53770, the dangerous ExpandedWrapper object is placed in the list. This makes CVE-2025-53770 an updated fix for CVE-2020-1147. Conclusions Despite the fact that patches for the ToolShell vulnerabilities are now available for deployment, we assess that this chain of exploits will continue being used by attackers for a long time. We have been observing the same situation with other notorious vulnerabilities, such as ProxyLogon, PrintNightmare, or EternalBlue. While they have been known for years, many threat actors still continue leveraging them in their attacks to compromise unpatched systems. We expect the ToolShell vulnerabilities to follow the same fate, as they can be exploited with extremely low effort and allow full control over the vulnerable server. To stay better protected against threats like ToolShell, we as a community should learn lessons from previous events in the industry related to critical vulnerabilities. Specifically, the speed of applying security patches nowadays is the most important factor when it comes to fighting such vulnerabilities. Since public exploits for these dangerous vulnerabilities appear very soon after vulnerability announcements, it is paramount to install patches as soon as possible, as a gap of even a few hours can make a critical difference. At the same time, it is important to protect enterprise networks against zero-day exploits, which can be leveraged when there is no available public patch for vulnerabilities. In this regard, it is critical to equip machines with reliable cybersecurity solutions that have proven effective in combatting ToolShell attacks before they were publicly disclosed. Kaspersky Next with its Behaviour detection component proactively protects against exploitation of these vulnerabilities. Additionally, it is able to detect exploitation and the subsequent malicious activity. Kaspersky products detect the exploits and malware used in these attacks with the following verdicts: UDS:DangerousObject.Multi.Generic PDM:Exploit.Win32.Generic PDM:Trojan.Win32.Generic HEUR:Trojan.MSIL.Agent.gen ASP.Agent.* PowerShell.Agent.*
6 shared
Jul 28, 2025
US Tops Hit List as 396 SharePoint Systems Compromised Globally
Check Point Research (CPR) conducted a focused analysis of Storm-2603, a threat actor associated with recent ToolShell exploitations, together with other Chinese APT groups. Storm-2603 utilizes a custom malware Command and Control (C2) framework dubbed internally by the attacker as “ak47c2”. This framework includes at least two different types of clients: HTTP-based (dubbed by us “ak47http”) and DNS-based (dubbed by us “ak47dns”). Based on VirusTotal data, Storm-2603 likely targeted some organizations in Latin America throughout the first half of 2025, in parallel to attacking organizations in APAC. Some of the actor’s TTPs align with many other ransomware groups, and involve open-source tools such as PsExec and masscan. In addition, the threat actors use a custom tool that leverages the BYOVD (Bring Your Own Vulnerable Driver) technique to tamper with endpoint protections. Storm-2603 attacks involved multiple ransomware families, sometimes bundled together. Those are commonly deployed by abusing DLL hijacking. Check Point Research (CPR) has been closely monitoring the ongoing exploitation of a group of Microsoft SharePoint Server vulnerabilities collectively referred to as “ToolShell.” These active attacks leverage four vulnerabilities—CVE-2025-49704, CVE-2025-49706, CVE-2025-53770, and CVE-2025-53771—and are attributed to multiple China affiliated threat actors. Among the threat groups identified by Microsoft, two are known APTs: Linen Typhoon (aka APT27) and Violet Typhoon (aka APT31). Another group is a newly observed, previously undocumented cluster called Storm-2603. While Microsoft linked this cluster’s activity to potential ransomware deployment, it was unable to assess the group’s objectives. As part of our ongoing investigation into ToolShell and its associated risks, we launched a targeted effort to better understand and characterize the threat posed by Storm-2603. Throughout our analysis, we uncovered several files likely tied to Storm-2603 intrusions, offering new insights that correspond to Microsoft’s description of the group. In this publication, we provide an in-depth examination of Storm-2603’s tactics, techniques, and procedures (TTPs), along with a technical breakdown of the ak47c2, a custom malware framework used in their attacks and their different ransomware payloads. Storm-2603 was first mentioned by Microsoft during investigations into a set of attacks on Microsoft SharePoint servers, known as the “ToolShell” campaign. While some activity was tied to known Chinese affiliated groups like Linen Typhoon (APT27) and Violet Typhoon (APT31), Storm-2603 appeared as a new, previously unreported actor. Microsoft linked the group to Lockbit and Warlock ransomware use. Figure 1 – Events associated with Storm-2603. Microsoft’s report provided only limited information about Storm-2603, including some of the TTPs associated with it, most of them quite generic. In addition, some of the reported indicators of compromise (IOCs) helped us uncover additional artifacts associated with previous Storm-2603 intrusions. One domain in particular, update.updatemicfosoft[.]com, linked to Storm-2603’s SharePoint exploitation, turned out to have been used in earlier campaigns dating back to March 2025. In those operations, it served as a C2 server for both DNS tunneling malware and an HTTP backdoor and was part of infrastructure used to deliver LockBit Black and Warlock/x2anylock ransomware. Our search for cases where the IOCs reported by Microsoft, revealed two incidents in which LockBit Black and WarLock ransomware variants were deployed together, in addition to multiple other tools, mostly open-source. In April 2025, a RAR archive named Evidencia.rar was uploaded to VirusTotal. The archive contains several artifacts likely extracted from compromised machines in a Storm-2603 case in a LATAM country. The artifacts in the archive provide a look at some of the open-source tools used by the actors in the intrusions which correlates with previous knowledge of the group: WinPcap – Captures and filters network traffic on Windows. PsExec – Executes commands on remote Windows systems. SharpHostInfo – Collects host and domain info on Windows environments. nxc – Exploits common vulnerabilities in network services. In addition to the open-source tools, the archive also contains the custom backdoor used by the group, as well as its unique ransomware payloads. dnsclient.exe – A custom backdoor utilized by Storm-2603 that communicates over DNS tunneling with update.updatemicfosoft[.]com, a domain associated with the group. See the next section for our analysis of the backdoor. 7z.exe & 7z.dll – Legitimate 7z executable side-loading malicious 7z.dll delivering X2anylock (aka Warlock), a ransomware used by Storm-2603. bbb.msi – An installer which uses clink_x86.exe to side-load clink_dll_x86.dll, leading to the execution of LockBit Black ransomware. Another MSI file uploaded to VirusTotal in April used a similar deployment method, starting with the MSI installer to launch multiple ransomware strains simultaneously: Figure 2 – MSI Multi-Ransomware Deployment. The MSI relies on the following files: MpCmdRun.exe & Mpclient.dll – Warlock Ransomware, deployed via DLL-hijacking. clink_x86.exe & clink_dll_x86.dll – LockBit Black ransomware, deployed via DLL-hijacking. z.exe & z.dll – x2anylock ransomware, deployed via DLL-hijacking. VMToolsEng.exe – Custom Antivirus Terminator. ServiceMouse.sys – Vulnerable driver used by VMToolsEng.exe for killing Antivirus processes. log.exe – A list of Antivirus processes to kill. msi.bat – Executes VMToolsEng.exe. 1.bat – Executes all the needed executables and the MSI. We attributed two custom backdoors to Storm-2306, both of which appear to be part of the framework named AK47 C2 based on the shared PDB path: C:\Users\Administrator\Desktop\work\tools\ak47c2\. When executed, the program immediately hides its console window, determines the host computer name (defaulting to unknown.local if that fails), and builds a DNS‑based command‑and‑control payload. It chooses a random five-character session ID, such as H4T14, and prefixes it with 1 for task requests or 2 for result uploads (e.g., 1H4T14 or 2H4T14). Each element, such as the task/result tag, a size flag (a for “all” when the entire message fits into one request), and the computer name, is XOR‑encoded with the ASCII key “VHBD@H”, converted to hexadecimal, and concatenated with dots before being prepended to the C2 domain update.micfosoft[.]com. This what the overall query looks like: DNS TXT and MG (a mail group member record type) record lookups (DnsQuery_A) are used to transmit and retrieve data. If the C2 server is unreachable, the client simply receives error 9003 (DNS_ERROR_RCODE_NAME_ERROR). Otherwise, the response text is decoded from hex, XOR‑decrypted, and parsed for the delimiter “:::”, which separates metadata from the actual command string. Commands run under cmd.exe /c 2>&1; a built‑in directive sleep n pauses execution for n seconds. For outputs larger than 0xFF bytes, the backdoor fragments data into 63‑byte sub‑segments. Each DNS query then follows: HttpClient backdoor has the pdb path C:\Users\Administrator\Desktop\work\tools\ak47c2\httpclient-cpp\x64\Release\httpclient-cpp.pdb and uses plain HTTP instead of DNS for the C2. It is built as a 64‑bit console program that also immediately hides its window on launch. On start‑up, the malware gathers the host computer name (similar to the DNS version, it defaults to unknown.local), then builds a JSON object with the fields cmd, cmd_id, fqdn, result, and type. For a task request, the object looks like this: {"cmd":"","cmd_id":"","fqdn":" ","result":"","type":"task"} After the host executes a command, the result is sent back with type:”result”. Before transmission, the entire JSON blob is XOR‑encrypted with the ASCII key “VHBD@H”, converted to hexadecimal, and placed in the body of an HTTP POST to “/” with generic headers (Content‑Type: text/plain, Accept: */*). The C2 replies with a similarly encoded JSON where the cmd field contains the next command. The implant executes it via cmd.exe /c 2>&1 and returns the output. We identified that during these attacks, several types of ransomware were deployed simultaneously. One is regular LockBit Black, and the second uses the.x2anylock extension. This extension was later used by the Warlock ransomware operator, mentioned in Microsoft’s report on the SharePoint exploitation. The Warlock ransom note is usually saved as How to decrypt my data.txt and looks like this: Figure 3 – Warlock Group ransom note. The ransom notes for all ransomware strains deployed by Storm-2603 are named How to decrypt my data.log (x2anylock) or .README.txt (LockBit Black) and have the same short content: Your decrypt ID: [redacted] Tox ID Support: 3DCE[redacted] Email Support: [redacted]@proton.me,[redacted]@proton.me,[redacted]@proton.me You can contact us in email or qtox. This ransom note’s name How to decrypt my data.log appeared in a recent LinkedIn post by Huntress, describing the case where multiple ransomware families were deployed together against the same target. While not a new tactic, this approach is rarely observed among established ransomware groups. An important part of the infection package described earlier is called Antivirus Terminator. It is a custom command line tool abusing a third-party signed legitimate driver to kill processes. From what we can see, it’s been in the wild since at least late 2024. The tool requires administrative privileges on the infected machine. The screenshot below shows how the listing is displayed in the console when the tool is run without parameters: Figure 4 – Antivirus Terminator supported arguments when run without parameters. The tool first creates a service called ServiceMouse, where the path to the service binary file is ServiceMouse.sys from the package. Next, the tool communicates with the installed service via IO control code 0x99000050, which is responsible for killing processes. The tool also has more capabilities, like deleting files and uninstalling drivers, and these use different IO control codes (0x990000D0 and 0x990001D0). Figure 6 – Antivirus Terminator kills process using third-party driver. The supplied third-party driver is a legitimate and signed component of Antiy System In-Depth Analysis Toolkit, originally named AToolsKrnl64.sys. The toolkit was developed by Antiy Labs, a Chinese security vendor, and features a graphical user interface that allows users, among others, to interact with and manipulate processes. The ability to kill processes is the most important feature which is abused by threat actors in this particular case. Figure 7 – Antiy System In-Depth Analysis Tookit GUI. The following piece of code in the driver handles the IO control code 0x99000050 mentioned above: Figure 8 – IO control code processing in the Antiy driver. The second function is the piece of code responsible for killing a process with a given PID. In this report we analyze Storm-2603, a relatively new threat actor first mentioned by Microsoft during investigations into the “ToolShell” campaign targeting SharePoint servers. While some of the exploitation activity was tied to known Chinese APT groups, Storm-2603 stood out as a previously undocumented group linked to ransomware deployment. By examining infrastructure indicators shared in public reporting, we were able to connect this actor to earlier campaigns involving LockBit Black and Warlock/X2anylock ransomware, dating back to at least March 2025. These earlier attacks used similar infrastructure and tools, including DNS tunneling and HTTP-based backdoors. Interestingly, multiple ransomware variants were deployed in the same attack. This behavior, along with the overlap in techniques, helps us better understand how Storm-2603 operates “The Turkish Rat” Evolved Adwind in a Massive Ongoing Phishing Campaign Check Point Research Publications August 11, 2017 “The Next WannaCry” Vulnerability is Here Check Point Research Publications March 12, 2026 “Handala Hack” – Unveiling Group’s Modus Operandi SUBSCRIBE TO CYBER INTELLIGENCE REPORTS We value your privacy! BFSI uses cookies on this site. We use cookies to enable faster and easier experience for you. By continuing to visit this website you agree to our use of cookies.
5 shared
Aug 1, 2025
US Tops Hit List as 396 SharePoint Systems Compromised Globally
On July 19–20, 2025, various security companies and national CERTs published alerts about active exploitation of on-premise SharePoint servers. According to the reports, observed attacks did not require authentication, allowed attackers to gain full control over the infected servers, and were performed using an exploit chain of two vulnerabilities: CVE-2025-49704 and CVE-2025-49706, publicly named “ToolShell”. Additionally, on the same dates, Microsoft released out-of-band security patches for the vulnerabilities CVE-2025-53770 and CVE-2025-53771, aimed at addressing the security bypasses of previously issued fixes for CVE-2025-49704 and CVE-2025-49706. The release of the new, “proper” updates has caused confusion about exactly which vulnerabilities attackers are exploiting and whether they are using zero-day exploits. Kaspersky products proactively detected and blocked malicious activity linked to these attacks, which allowed us to gather statistics about the timeframe and spread of this campaign. Our statistics show that widespread exploitation started on July 18, 2025, and attackers targeted servers across the world in Egypt, Jordan, Russia, Vietnam, and Zambia. Entities across multiple sectors were affected: government, finance, manufacturing, forestry, and agriculture. While analyzing all artifacts related to these attacks, which were detected by our products and public information provided by external researchers, we found a dump of a POST request that was claimed to contain the malicious payload used in these attacks. After performing our own analysis, we were able to confirm that this dump indeed contained the malicious payload detected by our technologies, and that sending this single request to an affected SharePoint installation was enough to execute the malicious payload there. Our analysis of the exploit showed that it did rely on vulnerabilities fixed under CVE-2025-49704 and CVE-2025-49706, but by changing just one byte in the request, we were able to bypass those fixes. In this post, we provide detailed information about CVE-2025-49704, CVE-2025-49706, CVE-2025-53770, CVE-2025-53771, and one related vulnerability. Since the exploit code is already published online, is very easy to use, and poses a significant risk, we encourage all organizations to install the necessary updates. The exploit Our research started with an analysis of a POST request dump associated with this wave of attacks on SharePoint servers. We can see that this POST request targets the “/_layouts/15/ToolPane.aspx” endpoint and embeds two parameters: “MSOtlPn_Uri” and “MSOtlPn_DWP”. Looking at the code of ToolPane.aspx, we can see that this file itself does not contain much functionality and most of its code is located in the ToolPane class of the Microsoft.SharePoint.WebPartPages namespace in Microsoft.SharePoint.dll. Looking at this class reveals the code that works with the two parameters present in the exploit. However, accessing this endpoint under normal conditions is not possible without bypassing authentication on the attacked SharePoint server. This is where the first Microsoft SharePoint Server Spoofing Vulnerability CVE-2025-49706 comes into play. CVE-2025-49706 This vulnerability is present in the method PostAuthenticateRequestHandler, in Microsoft.SharePoint.dll. SharePoint requires Internet Information Services (IIS) to be configured in integrated mode. In this mode, the IIS and ASP.NET authentication stages are unified. As a result, the outcome of IIS authentication is not determined until the PostAuthenticateRequest stage, at which point both the ASP.NET and IIS authentication methods have been completed. Therefore, the PostAuthenticateRequestHandler method utilizes a series of flags to track potential authentication violations. A logic bug in this method enables an authentication bypass if the “Referrer” header of the HTTP request is equal to “/_layouts/SignOut.aspx”, “/_layouts/14/SignOut.aspx”, or “/_layouts/15/SignOut.aspx” using case insensitive comparison. The code displayed in the image above handles the sign-out request and is also triggered when the sign-out page is specified as the referrer. When flag6 is set to false and flag7 is set to true, both conditional branches that could potentially throw an “Unauthorized Access” exception are bypassed. On July 8, 2025, Microsoft released an update that addressed this vulnerability by introducing additional checks to detect the usage of the “ToolPane.aspx” endpoint with the sign-out page specified as the referrer. The added check uses case insensitive comparison to verify if the requested path ends with “ToolPane.aspx”. Is it possible to bypass this check, say, by using a different endpoint? Our testing has shown that this check can be easily bypassed. CVE-2025-53771 We were able to successfully bypass the patch for vulnerability CVE-2025-49706 by adding just one byte to the exploit POST request. All that was required to bypass this patch was to add a “/” (slash) to the end of the requested “ToolPane.aspx” path. On July 20, 2025, Microsoft released an update that fixed this bypass as CVE-2025-53771. This fix replaces the “ToolPane.aspx” check to instead check whether the requested path is in the list of paths allowed for use with the sign-out page specified as the referrer. This allowlist includes the following paths: “/_layouts/15/SignOut.aspx”, “/_layouts/15/1033/initstrings.js”, “/_layouts/15/init.js”, “/_layouts/15/theming.js”, “/ScriptResource.axd”, “/_layouts/15/blank.js”, “/ScriptResource.axd”, “/WebResource.axd”, “/_layouts/15/1033/styles/corev15.css”, “/_layouts/15/1033/styles/error.css”, “/_layouts/15/images/favicon.ico”, “/_layouts/15/1033/strings.js”, “/_layouts/15/core.js”, and it can contain additional paths added by the administrator. While testing the CVE-2025-49706 bypass with the July 8, 2025 updates installed on our SharePoint debugging stand, we noticed some strange behavior. Not only did the bypass of CVE-2025-49706 work, but the entire exploit chain did! But wait! Didn’t the attackers use an additional Microsoft SharePoint Remote Code Execution Vulnerability CVE-2025-49704, which was supposed to be fixed in the same update? To understand why the entire exploit chain worked in our case, let’s take a look at the vulnerability CVE-2025-49704 and how it was fixed. CVE-2025-49704 CVE-2025-49704 is an untrusted data deserialization vulnerability that exists due to improper validation of XML content. Looking at the exploit POST request, we can see that it contains two URL encoded parameters: “MSOtlPn_Uri” and “MSOtlPn_DWP”. We can see how they are handled by examining the code of the method GetPartPreviewAndPropertiesFromMarkup in Microsoft.SharePoint.dll. A quick analysis reveals that “MSOtlPn_Uri” is a page URL that might be pointing to an any file in the CONTROLTEMPLATES folder and the parameter “MSOtlPn_DWP” contains something known as WebPart markup. This markup contains special directives that can be used to execute safe controls on a server and has a format very similar to XML. While this “XML” included in the “MSOtlPn_DWP” parameter does not itself contain a vulnerability, it allows attackers to instantiate the ExcelDataSet control from Microsoft.PerformancePoint.Scorecards.Client.dll with CompressedDataTable property set to malicious payload and trigger its processing using DataTable property getter. Looking at the code of the ExcelDataSet’s DataTable property getter in Microsoft.PerformancePoint.Scorecards.Client.dll, we find the method GetObjectFromCompressedBase64String, responsible for deserialization of CompressedDataTable property contents. The data provided as Base64 string is decoded, unzipped, and passed to the BinarySerialization.Deserialize method from Microsoft.SharePoint.dll. Attackers use this method to provide a malicious DataSet whose deserialized content is shown in the image above. It contains an XML with an element of dangerous type "System.Collections.Generic.List1[[System.Data.Services.Internal.ExpandedWrapper2[...], System.Data.Services, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089]]", which allows attackers to execute arbitrary methods with the help of the well-known ExpandedWrapper technique aimed at exploitation of unsafe XML deserialization in applications based on the .NET framework. In fact, this shouldn’t be possible, since BinarySerialization.Deserialize in Microsoft.SharePoint.dll uses a special XmlValidator designed to protect against this technique by checking the types of all elements present in the provided XML and ensuring that they are on the list of allowed types. However, the exploit bypasses this check by placing the ExpandedWrapper object into the list. Now, to find out why the exploit worked on our SharePoint debugging stand with the July 8, 2025 updates installed, let’s take a look at how this vulnerability was fixed. In this patch, Microsoft did not really fix the vulnerability but only mitigated it by adding the new AddExcelDataSetToSafeControls class to the Microsoft.SharePoint.Upgrade namespace. This class contains new code that modifies the web.config file and marks the Microsoft.PerformancePoint.Scorecards.ExcelDataSet control as unsafe. Because SharePoint does not execute this code on its own after installing updates, the only way to achieve the security effect was to manually run a configuration upgrade using the SharePoint Products Configuration Wizard tool. Notably, the security guidance for CVE-2025-49704 does not mention the need for this step, which means at least some SharePoint administrators may skip it. Meanwhile, anyone who installed this update but did not manually perform a configuration upgrade remained vulnerable. CVE-2025-53770 On July 20, 2025, Microsoft released an update with a proper fix for the CVE-2025-49704 vulnerability. This patch introduces an updated XmlValidator that now properly validates element types in XML, preventing exploitation of this vulnerability without requiring a configuration upgrade and, more importantly, addressing the root cause and preventing exploitation of the same vulnerability through controls other than Microsoft.PerformancePoint.Scorecards.ExcelDataSet. CVE-2020-1147 Readers familiar with previous SharePoint exploits might feel that the vulnerability CVE-2025-49704/CVE-2025-53770 and the exploit used by the attackers looks very familiar and very similar to the older .NET Framework, SharePoint Server, and Visual Studio Remote Code Execution Vulnerability CVE-2020-1147. In fact, if we compare the exploit for CVE-2020-1147 and an exploit for CVE-2025-49704/CVE-2025-53770, we can see that they are almost identical. The only difference is that in the exploit for CVE-2025-49704/CVE-2025-53770, the dangerous ExpandedWrapper object is placed in the list. This makes CVE-2025-53770 an updated fix for CVE-2020-1147. Conclusions Despite the fact that patches for the ToolShell vulnerabilities are now available for deployment, we assess that this chain of exploits will continue being used by attackers for a long time. We have been observing the same situation with other notorious vulnerabilities, such as ProxyLogon, PrintNightmare, or EternalBlue. While they have been known for years, many threat actors still continue leveraging them in their attacks to compromise unpatched systems. We expect the ToolShell vulnerabilities to follow the same fate, as they can be exploited with extremely low effort and allow full control over the vulnerable server. To stay better protected against threats like ToolShell, we as a community should learn lessons from previous events in the industry related to critical vulnerabilities. Specifically, the speed of applying security patches nowadays is the most important factor when it comes to fighting such vulnerabilities. Since public exploits for these dangerous vulnerabilities appear very soon after vulnerability announcements, it is paramount to install patches as soon as possible, as a gap of even a few hours can make a critical difference. At the same time, it is important to protect enterprise networks against zero-day exploits, which can be leveraged when there is no available public patch for vulnerabilities. In this regard, it is critical to equip machines with reliable cybersecurity solutions that have proven effective in combatting ToolShell attacks before they were publicly disclosed. Kaspersky Next with its Behaviour detection component proactively protects against exploitation of these vulnerabilities. Additionally, it is able to detect exploitation and the subsequent malicious activity. Kaspersky products detect the exploits and malware used in these attacks with the following verdicts: UDS:DangerousObject.Multi.Generic PDM:Exploit.Win32.Generic PDM:Trojan.Win32.Generic HEUR:Trojan.MSIL.Agent.gen ASP.Agent.* PowerShell.Agent.*
5 shared
Jul 31, 2025
2026-013: Critical Vulnerability in F5 BIG-IP APM
History: 22/09/2026 --- v1.0 -- Initial publication Summary On 22 September 2026, F5 published an advisory addressing a critical vulnerability affecting its BIG-IP APM product. The vendor confirmed active exploitation in the wild [1]. CERT-EU recommends taking appropriate actions as soon as possible. Technical Details The vulnerability CVE-2026-94127, with a CVSS score of 9.8, is a heap-based buffer overflow vulnerability and allow unauthenticated attacker to achieve remote code execution (RCE) on the affected device [1]. Affected Products The vulnerability affects the following versions of BIG-IP APM if configured with an access policy and an OAuth profile on a virtual server [1]: 17.1.0 - 17.1.3 17.5.0 - 17.5.1 21.1.0 Recommendations CERT-EU recommends taking the following actions as soon as possible: Preserve forensic evidence. Apply the relevant hotfix. Check for signs of compromise (see the compromise assessment section). If any sign of compromise is detected, start the incident response process. Mitigation If patching cannot be applied immediately, F5 provides an iRule-based mitigation for the affected virtual server. To obtain it, F5 BIG-IP clients should contact the F5 support [1]. Compromise Assessment CERT-EU strongly advises to look for the following indicators of compromise provided by the vendor in its advisory [1]: At a high level, multiple OAuth authentication failures, followed by suspicious commands, shortly followed by a TMM SIGABRT is the combination that should lead to human review of the system. OAuth authentication failures: check /var/log/apm for repeated occurrences of the following, especially 10 or more from a single IP in a short window. err tmm1\[30975\]: 01990004:3: : Request UserInfo from Source ID (null) IP failed. Error Code (invalid\_token) Error Description (The access token is invalid.) - Increase of OAuth failure statistics. Run the following and look for an unexplained increase in total_failed : $ tmctl global_oauth_stat -s total_requests,total_userinfo_requests,total_failed - Audit log anomalies: if OAuth failures are observed, review /var/log/audit around those timestamps for suspicious commands. TMM core files: Presence of a TMM core file alone is not an indicator, but core files should be investigated. The vendor indicates that they have observed TMM entering a loop, which causes the SOD daemon to send a SIGABRT.
5 shared
Sep 25, 2026