Attackers Exploit Third Arista VCO Zero-Day in Four Months

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.

Attackers exploited a previously unknown flaw in Check Point's Security Management Server in a handful of targeted attacks on July 23, the company said. The flaw, CVE-2026-93616, allows an attacker who can access the server's web service to run scripts on it without logging in. Check Point released a fix on September 22 for the server that controls firewall policies for the Check Point gateways it manages. Separately, Check Point said attackers have been trying since September 12 to exploit a VPN flaw it fixed on September 9. The attempts, against a flaw tracked as CVE-2026-85102, have targeted customers of Spark, Check Point's firewall line for small businesses. When the fix came out, Check Point had no evidence the flaw was being exploited. CVE-2026-93616 is a path traversal bug in the management server's web service. The service does not properly limit which files and folders a request can reach. An attacker can use it to upload scripts to the server and then run them. Check Point rated it 9.8 out of 10 on the CVSS scale in the CVE record for the flaw. Check Point's advisory does not name the targets of the July attacks or the attackers, nor does it say what the attackers did after exploiting the flaw. Management Server Versions and Fix Check Point numbers the Jumbo Hotfix updates for each release by "Take." Its LivePatch channel, which pushes urgent fixes, uses a separate set of take numbers. The CVE record lists these versions as affected: R82.20 with no Jumbo Hotfix installed R82.10 with Jumbo Hotfix Take 44 or below R82 with Jumbo Hotfix Take 126 or below R81.20 with Jumbo Hotfix Take 166 or below R81.10 with Jumbo Hotfix Take 190 or below (end of support) R81, R80.40, R80.30, R80.20, R80.10 and R80 (all end of support) Check Point's advisory lists R82.20 as affected without the "no Jumbo Hotfix" condition. On September 16, Check Point fixed a separate flaw in the management server, CVE-2026-91843, through LivePatch. That update was LivePatch Take 28, or Take 29 on R82.20, according to a summary of Check Point's advisory by France's CERT Santé. Check Point says those LivePatch takes do not fix CVE-2026-93616. CVE-2026-85103, a VPN certificate flaw that Check Point fixed on September 9, affected both gateways and management servers. On R82.10, R82, and R81.20, the new flaw's affected list goes one take higher than that flaw's. So a server updated only enough to be outside that September flaw's range is still affected by CVE-2026-93616. The fixed builds, and Check Point's guidance on mitigation, hunting and indicators of compromise, are in support article sk1000171. Administrators of management servers should: Check the server's release and Jumbo Hotfix take against the list above. Install the fix listed in sk1000171. Use the hunting guidance and indicators of compromise in sk1000171 to look for signs of an attack. Installing the fix does not show whether the server was attacked before. Check Point's advisory names only Security Management as affected and does not say what network access an attacker needs. The Hacker News has asked Check Point about other affected products, the fixed builds, and the July attacks. Spark Firewalls Targeted Through VPN Flaw CVE-2026-85102 is in the way Check Point gateways check certificates while a VPN connection is being set up. It may let an attacker who has not logged in run code on the gateway. Fixes have been out since September 9 and are in support article sk1000117. The affected products are Security Gateway and Spark firewalls, whether centrally or locally managed, on R81 and R81.10 (both end of support), R81.10.x, R81.20, R82, R82.00.x and R82.10. The Netherlands' National Cyber Security Centre (NCSC) says the flaw applies when these products use Site-to-Site VPN or Remote Access VPN. Check Point said the attempts came from anonymizing infrastructure, including VPN services and proxies, and used certificates with these subjects: Certificate subject: CN=vpn,OU=users,O=global Certificate subject: CN=vpn-user,OU=users,O=global Certificate subject: CN=vpnuser,OU=users,O=global The list is not complete, and other subjects may be in use. Administrators should check logs for any unusual certificate-based Mobile Access login, not only those with these subjects. They should also check what suspicious Mobile Access users do after logging in, which often includes scanning internal ports and services. Check Point says customers who installed the September 9 fix are protected, but its advisory does not say whether any attempt succeeded. For gateways that cannot be patched yet, the NCSC lists a Check Point workaround for Site-to-Site VPN: turn off the implied VPN rules and allow UDP ports 500 and 4500 only from specific peer IP addresses. The workaround does not apply to locally managed Spark firewalls. Mitigation steps from Check Point are in sk1000117.

Check Point Software has released emergency fixes for a critical Check Point Management Server vulnerability (CVE-2026-93616) that has been exploited as far back as July 23, 2026. The company also confirmed that a pre-authentication remote code execution (RCE) vulnerability (CVE-2026-85102) in Check Point (Quantum) Security Gateway for which it released patches on September 9, 2026, started getting probed a few days after. “At the time [of the release of the patches], we had no evidence … More → The post Attackers hit Check Point Management Servers and Spark firewalls, F5 BIG-IP APM instances appeared first on Help Net Security .

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.*

Attackers are exploiting a new critical zero-day flaw in Cisco Catalyst SD-WAN Manager, the system companies use to manage their Cisco SD-WAN networks, Cisco said in an advisory on September 30. The flaw, CVE-2026-76504, could allow a remote attacker with no login access to use the Manager's API as the admin user. Fixed releases are available, and there is no workaround. It carries a CVSS score of 9.8 out of 10. It sits in the part of the Manager's API that handles login sessions. The Manager mishandles URI encoding in an HTTP request. A crafted request can therefore bypass an authentication rule intended to restrict access to a single API endpoint. The attacker needs no credentials, only the ability to send that request to the Manager's API. Managers exposed to the internet are at risk of compromise, according to Cisco. By default, the admin user holds the netadmin role, which is allowed to perform all operations on the device. Cisco said its Product Security Incident Response Team "became aware of active exploitation of this vulnerability" in September 2026. The flaw was found while Cisco's Technical Assistance Center (TAC) was handling a support case. The advisory does not say how many customers were attacked, when the attacks began, who carried them out, or what the attackers did with the access. Who Needs to Upgrade The flaw affects SD-WAN Manager regardless of how the system is configured. No other product is listed as affected. These are the first fixed releases for each release train: CVE-2026-76504 is separate from three Cisco SD-WAN flaws fixed earlier: CVE-2026-20182 in May, and CVE-2026-20245 and CVE-2026-20262 in June. A comparison of the advisories shows that the fixed releases for those flaws are all older than the ones in the table above. So a Manager last upgraded for the May or June fixes still needs this update. The table does not list the 20.10, 20.11, 20.13, 20.14, or 20.16 release trains, which Cisco's May advisory did list. The advisory also does not name Cisco SD-WAN Cloud-Pro or Cisco SD-WAN for Government (FedRAMP), two deployment types named in the May and June advisories. Cisco SD-WAN Cloud (Cisco Managed) is already fixed in release 20.15.605, and customers on it need to take no action. Until an on-prem Manager is upgraded, Cisco advises restricting access to it from unsecured networks such as the internet. Where internet access is required, only known, trusted hosts should be allowed in, and the control components should sit behind a firewall. Cisco Catalyst SD-WAN Cloud Hosted environments already have this mitigation in place. The mitigation worked in a test environment, according to Cisco, which advises customers to assess its impact on their own networks before applying it. Cisco's SD-WAN hardening guide says administrative interfaces, such as ports 443, 22 and 830, should not be exposed directly to the internet. HTTPS access to the Manager should come only from a jump host or a management subnet. Checking for Signs of Compromise The signs of compromise Cisco describes involve j_security_check, the request path the Manager uses for session-based logins. In Cisco's example, one character of that path is URI-encoded, giving /%6a_security_check, where %6a stands for the letter j. Two log files are the places to look for j_security_check entries from unknown or unauthorized IP addresses: File: /var/log/nms/containers/service-proxy/serviceproxy-access.log File: /var/log/nms/vmanage-server.log, in particular entries for users whose names start with viptela-reserved- Names starting with viptela-reserved- belong to reserved system service accounts. Any one character in the request can be encoded, so %6a is only an example. The same entries can also appear during normal operation, and each match has to be checked against normal activity to avoid false positives. To help determine whether a Manager has been compromised, customers can open a Severity 3 case with Cisco TAC and include CVE-2026-76504 in the title. Cisco asks them to run request admin-tech on the Manager first, so the output file can be reviewed. The advisory includes no detection rule and does not say whether upgrading removes an attacker who already has access. Cisco's advisories for the May flaw and the first June flaw said an update alone would not resolve a confirmed compromise. They told customers to collect the admin-tech file before upgrading. CVE-2026-76504 follows a series of Cisco SD-WAN flaws flagged as exploited this year. As of September 30, the U.S. Cybersecurity and Infrastructure Security Agency's (CISA) Known Exploited Vulnerabilities catalog listed eight Cisco SD-WAN flaws added in 2026.

The public still doesn’t know who is abusing a critical Citrix vulnerability exploited as a zero-day weeks before disclosure, but we now know that the unknown digital intruders have used CVE-2026-88772 to break into government agencies, financial services firms, education organizations, and legal and professional services sectors across North America and Europe. And everyone agrees that the vendor took way too long to disclose the security holes. GreyNoise said it spotted an attempt to exploit CVE-2026-88771 against a Citrix NetScaler Gateway on September 24. Google researchers, meanwhile, said the CVE-2026-88772 campaign has been ongoing “since at least early September.” “Why Citrix took so long to disclose these vulnerabilities is a question only Citrix can answer,” Benjamin Harris, founder and CEO of exposure management firm watchTowr, told The Register. Citrix declined to answer The Register's questions about the scope of the attacks, and why it didn't alert the public about the CVEs under active exploitation until Sunday. “The vulnerabilities were discovered during incident response and forensic investigations at organizations already compromised, meaning both the exploitation and Citrix’s awareness of it predated public disclosure,” Harris said. “Citrix has a history of delaying the publication of vulnerabilities, even when they’re being exploited in the wild and affecting customers.” So if you use Citrix NetScaler ADC and NetScaler Gateway appliances, and haven’t already applied the security updates, do that ASAP. But first, check your systems for signs of compromise, warns Mandiant Consulting CTO Charles Carmakal. “Given the active exploitation, NetScaler customers should prioritize examining their systems for compromise *before* upgrading/patching,” Carmakal said on LinkedIn. “If you find evidence of web shells or other malicious files, please preserve evidence and investigate the scope of the compromise. Patching alone may not eradicate the threat actor from your environment.” No attribution - yet Citrix disclosed eight CVEs on Sunday with the worst of the bunch – CVE-2026-88771 and CVE-2026-88772 – earning critical 9.5 CVSS scores. “Exploitation of CVE-2026-88771 and CVE-2026-88772 on unmitigated NetScaler deployments has been observed,” the vendor said. CVE-2026-88771 can allow an unauthenticated attacker to execute arbitrary commands remotely. CVE-2026-88772 is a memory overflow vulnerability that can lead to remote code execution or denial of service when DTLS is enabled, as it is by default on VPN virtual servers. But by the time Citrix issued security advisories and warned customers about the vulnerabilities, they were already under attack. “No attribution has been made public, and we have yet to identify a clear trend among targets by industry or organization size,” Harris said. “Historically, NetScaler vulnerabilities have been exploited by both state-sponsored groups and ransomware operators.” WatchTowr on Tuesday published a technical writeup about CVE-2026-88772, plus a detection artifact generator for Citrix users to determine if they are vulnerable and to help with remediation. Also on Tuesday, Google’s threat intel businesses provided additional details about the exploitation campaign’s targets and the attacker’s custom malware. “We have observed evidence that organizations in North America and Europe in the government, financial services, education, legal and professional services sectors were likely impacted by this exploitation campaign, which has been ongoing since at least early September,” Google Threat Intelligence Group and Mandiant said in an advisory. Custom malware After analyzing the intruder’s post-exploit toolkit, the malware hunters found never-before-seen malware used to establish persistent root access and proxy traffic into internal corporate networks. The custom malware includes WHIPSHOT, a PHP web shell, and SLAPSHOT, a TCP tunneling tool written in Python. WHIPSHOT is disguised as a Debian package and hides Base64-encoded command-and-control payloads in native HTTP headers. It functions as an HTTP transport bridge for SLAPSHOT, which accepts commands from WHIPSHOT and forwards arbitrary TCP streams to internal hosts. Supported commands include: open, which establishes an outbound TCP socket to a target host and port. push, which writes data to an open session. pull, which polls and reads data from an open session socket. exch, which sends and receives command-and-control data to and from an open session socket. close, which terminates a specified network session. ping, which performs a basic health-check verification. “In at least one observed intrusion, the threat actor routed traffic through this proxy to manually conduct internal reconnaissance and credential theft,” the threat intel teams noted. Google did not immediately respond to The Register’s questions about the campaign, including how many exploitation attempts and successful intrusions its threat hunters observed. Its advisory notes that the Citrix campaign “underscores the continued targeting of edge devices to gain initial access to victim networks, a trend that GTIG has tracked across a range of threat actors.” Security and networking vulnerabilities accounted for about half of enterprise-related zero-days in 2025, according to Google’s count. Attackers love edge devices - application delivery controllers, VPN gateways, and firewalls - because they provide direct access from the open internet to corporate networks, allowing attackers to bypass endpoint detection tools and other security layers. NetScaler, in particular, is notoriously buggy. Attackers exploited another critical NetScaler vuln in March. A year earlier, Citrix disclosed multiple zero-days in the same product. ®