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Chinese APT Exploits Unpatched Windows Flaw in Recent Attacks

Diplomatic entities in Belgium and Hungary hacked in China-linked spy campaign Hungarian and Belgian diplomatic entities were allegedly targeted by a well-known Chinese hacking group in September and October. Incident responders at Arctic Wolf Labs discovered an active cyber-espionage campaign they attributed to a China-affiliated threat actor tracked as UNC6384. In August, Google spotlighted a nearly identical campaign by the same group targeting diplomats in Southeast Asia with documents mimicking EU Council meeting agendas. Arctic Wolf tracked the latest campaign over the last two months, writing in a blog post on Thursday that the attacks began with spearphishing emails centered on European Commission meetings, NATO-related workshops and multilateral diplomatic coordination events. In…

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7.8
In KEV
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3
Key vulnerabilities
CVE-2025-9491CVSS 7.8

Microsoft Windows LNK File UI Misrepresentation Remote Code Execution Vulnerability. This vulnerability allows remote attackers to execute arbitrary code on affected installations of Microsoft Windows. User interaction is required to exploit this vulnerability in that the target must visit a malicious page or open a malicious file. The specific flaw exists within the handling of .LNK files. Crafted data in an .LNK file can cause hazardous content in the file to be invisible to a user who inspects the file via the Windows-provided user interface. An attacker can leverage this vulnerability to execute code in the context of the current user. Was ZDI-CAN-25373.

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Unpatched Windows vulnerability continues to be exploited by APTs (CVE-2025-9491)
Unpatched Windows vulnerability continues to be exploited by APTs (CVE-2025-9491) A Windows vulnerability (CVE-2025-9491, aka ZDI-CAN-25373) that state-sponsored threat actors and cybercrime groups have been quietly leveraging since at least 2017 continues to be exploited for attacks. “Arctic Wolf Labs assesses with high confidence that [the campaign we detected] is attributable to UNC6384. This attribution is based on multiple converging lines of evidence including malware tooling, tactical procedures, targeting alignment, and infrastructure overlaps with previously documented UNC6384 operations,” the company’s threat researchers noted. The attack campaign The targets in this latest cyber espionage campaign were European diplomatic entities in Hungary, Belgium, Italy and the Netherlands, as well as Serbian government’s aviation departments. During September and October 2025, UNC6384 sent out spearphishing emails with an embedded URL, which ultimately lead to the delivery of malicious LNK files with themes related to European Commission meetings and NATO workshops. “These files exploit [CVE-2025-9491, aka ZDI-CAN-25373] to execute obfuscated PowerShell commands that extract and deploy a multi-stage malware chain, culminating in PlugX remote access trojan (RAT) deployment through DLL side-loading of legitimate signed Canon printer assistant utilities,” the researchers explained. CVE-2025-9491 exploited ZDI-CAN-25373 was publicly disclosed in March 2025 by Peter Girnus, a threat hunter with Trend Micro’s Zero Day Initiative, and it’s an example of User Interface Misrepresentation of Critical Information (CWE-451). The vulnerability allows attackers to create malicious LNK (Windows shortcut) files with command line arguments embedded in their Target field, but padded with whitespace (or other characters), thus making them unlikely to be seen by users who inspect the file via the Windows-provided user interface. If the shortcut file is run by a user, these arguments are passed to target machines and result in code execution. In conjunction with this trick, UNC6384 leveraged decoy PDF documents to hide the malicious payload being decrypted and executed in-memory via DLL side-loading. The attackers’ execution chain (Source: Arctic Wolf) “This three-stage execution flow completes the deployment of PlugX malware running stealthily within a legitimate signed process, significantly reducing the likelihood of detection by endpoint security solutions,” Arctic Wolf explained. “Also observed in early September, Arctic Wolf identified UNC6384’s use of an HTA file configured to run invisibly in the background, which loads external JavaScript from a CloudFront URL. The JavaScript facilitated payload retrieval from the same CloudFront-based C2 and served as a delivery mechanism for three critical files: cnmpaui.exe, cnmpauix.exe, and cnmplog.dat.” A fix may or may not be in the works ZDI reported ZDI-CAN-25373 to Microsoft in September 2024 and shared their knowledge of it having been exploited many times in the past by various state-sponsored and cybercrime groups from North Korea, Iran, Russia, and China. Microsoft acknowledged the report and the additional information provided, but ultimately decided that the vulnerability did not meet the bar for servicing. At the time, Microsoft told Help Net Security that Microsoft Defender has detections in place to detect and block this threat activity, and the Smart App Control provides an extra layer of protection by blocking malicious files from the Internet. But, they added, they would consider addressing it in a future feature release. We’ve reached out to Microsoft to ask whether they plan to fix the vulnerability soon (or at all), and we’ll update this article when we hear back from them. UPDATE (November 2, 2025, 02:15 p.m. ET): “We appreciate the work of the research community in sharing their findings,” a Microsoft spokesperson told Help Net Security, and reiterated their previous statements about Microsoft Defender’s detections and Smart App Control’s protection. “As a security best practice, we strongly encourage customers to heed security warnings and avoid opening files from unknown sources.” UPDATE (December 2, 2025, 10:50 a.m. ET): According to Mitja Kolsek, CEO of ACROS Security and co-founder of 0patch, Microsoft has patched the vulnerability in November, by making “the Properties dialog of a .lnk file [show] the entire Target command with arguments, no matter how long it is.” 0patch also created a micropatch for the issue, but decided to take an alternative route. “If the process opening the .lnk file is Windows Explorer, AND the Target has more than 260 characters, then we cut the Target at 260 characters and alert the user that a suspicious .lnk file was shortened,” he explained. “Our patch would break the 1000+ malicious shortcuts identified by Trend Micro for all targeted users, while Microsoft’s patch would only allow the most cautious among these users – who would probably not launch such shortcuts anyway – to see the entire malicious command string. Even though malicious shortcuts could be constructed with fewer than 260 characters, we believe disrupting actual attacks detected in the wild can make a big difference for those targeted.” “We’d like to thank Peter Girnus and Aliakbar Zahravi with Trend Micro for sharing the details, which allowed us to create a patch for our users,” he added. UPDATE (December 5, 2025, 04:00 a.m. ET): “Microsoft deployed this change in June 2025 but it may have been activated gradually,” Kolsek said after getting additional insight. “For instance, one of our testing Windows 11 24H2 computers we re-inspected had it activated in August. Our claim that it was deployed in November was therefore incorrect.” Subscribe to our breaking news e-mail alert to never miss out on the latest breaches, vulnerabilities and cybersecurity threats. Subscribe here!
helpnetsecurity.comOct 31, 2025extracted
Chinese APT Exploits Unpatched Windows Flaw in Recent Attacks
A Chinese threat actor has been exploiting an unpatched Windows shortcut vulnerability in fresh attacks targeting the diplomatic community in Europe, Arctic Wolf reports. The exploited flaw, tracked as CVE-2025-9491 (CVSS score of 7.0), is described as a UI misrepresentation issue, as Windows fails to show critical information (which can provide evidence of malicious activity) when the user inspects the file’s properties. The attacks seen by Arctic Wolf involve the distribution of LNK files designed to execute malicious code when opened by the victim. CVE-2025-9491 is exploited to make the malicious code invisible to a user who may look at the file’s properties. Trend Micro’s Zero Day Initiative (ZDI) reported the issue to Microsoft in September 2024. Microsoft has not released patches for the security defect, notifying ZDI that the issue does not meet the bar for servicing. In line with its disclosure policy, ZDI released information on the vulnerability in March this year. ZDI warned at the time that 11 state-sponsored APT groups from North Korea, Russia, China, and Iran have been abusing specially crafted LNK files in attacks targeting defense, energy, financial, government, military, telecoms, think tank, and private organizations. Microsoft told SecurityWeek that users rarely inspect a file’s properties to look for malicious code and Microsoft Defender is capable of detecting the use of this technique in LNK files. The tech giant also noted that attempting to open such a file that was downloaded from the internet automatically triggers a security warning, and said users should exercise caution when opening files fetched from the internet or received from untrusted sources. Now, Arctic Wolf says that UNC6384, a Chinese threat actor linked to the Mustang Panda APT, which is also tracked as Basin, Bronze President, Earth Preta, Red Delta, Temp.Hex, and Twill Typhoon, has been exploiting CVE-2025-9491 in attacks since September 2025. The hacking group has been targeting European diplomats with spear-phishing emails containing an embedded URL that initiates an infection chain leading to the delivery of the PlugX remote access trojan (RAT). At one stage in the infection chain, “malicious LNK files themed around European Commission meetings, NATO-related workshops, and multilateral diplomatic coordination events” are dropped to exploit the unpatched vulnerability. The exploit allows UNC6384 to execute PowerShell commands, drop a signed Canon printer utility, and abuse it to execute PlugX via DLL sideloading. “Arctic Wolf Labs assesses with high confidence that this campaign is attributable to UNC6384. This attribution is based on multiple converging lines of evidence including malware tooling, tactical procedures, targeting alignment, and infrastructure overlaps with previously documented UNC6384 operations,” the cybersecurity firm notes. In September and October, Arctic Wolf observed UNC6384 exploiting the bug in attacks aimed at Hungarian and Belgian diplomatic personnel. Additionally, the company linked the campaign with the targeting of Serbian government aviation departments and diplomatic entities in Italy and the Netherlands. “We appreciate the work of the research community in sharing their findings. Microsoft Defender has detections in place to identify and block this threat activity, and Smart App Control provides an additional layer of protection by blocking malicious files from the Internet. As a security best practice, we strongly encourage customers to heed security warnings and avoid opening files from unknown sources,” a Microsoft spokesperson said, responding to a SecurityWeek inquiry. *Updated with statement from Microsoft Related: Chinese APT ‘Phantom Taurus’ Targeting Organizations With Net-Star Malware Related: Chinese Cyberspies Hacked US Defense Contractors Related: Details Emerge on Chinese Hacking Operation Impersonating US Lawmaker
securityweek.comOct 31, 2025extracted
Diplomatic entities in Belgium and Hungary hacked in China-linked spy campaign
Diplomatic entities in Belgium and Hungary hacked in China-linked spy campaign Hungarian and Belgian diplomatic entities were allegedly targeted by a well-known Chinese hacking group in September and October. Incident responders at Arctic Wolf Labs discovered an active cyber-espionage campaign they attributed to a China-affiliated threat actor tracked as UNC6384. In August, Google spotlighted a nearly identical campaign by the same group targeting diplomats in Southeast Asia with documents mimicking EU Council meeting agendas. Arctic Wolf tracked the latest campaign over the last two months, writing in a blog post on Thursday that the attacks began with spearphishing emails centered on European Commission meetings, NATO-related workshops and multilateral diplomatic coordination events. In addition to the Hungarian and Belgian targets, Arctic Wolf said it saw documents targeting Serbian government aviation departments, as well as other diplomatic entities in Italy and the Netherlands. The diplomatic targets focused specifically on cross-border policy, defense cooperation and multilateral coordination activities. The researchers noted that Belgium's role as host nation for NATO headquarters and numerous EU institutions “makes Belgian diplomatic entities valuable intelligence targets for monitoring alliance activities and policy development.” Arctic Wolf did not specify what those entities were. The targeting indicates interest in NATO and EU defense initiatives, procurement decisions and military readiness assessments as well as European supply chain resilience, infrastructure development and trade policy evolution, the researchers explained. “The expansion to European diplomatic targeting observed in this campaign indicates either broadened operational mandate or deployment of additional operational teams with geographic specialization,” Arctic Wolf said. “The consistency in tooling and techniques across both geographic theaters suggests centralized tool development with regional operational deployment.” Panda’s PlugX The emails contained embedded URLs that eventually led to the delivery of malicious files that exploit a Windows vulnerability disclosed in March 2025. The attacks culminate in the use of PlugX — a brand of malware used by many Chinese nation-state groups. Arctic Wolf argued that the campaign “represents a tactical evolution from the group's previously documented operations, introducing exploitation of a recently disclosed Windows vulnerability alongside refined social engineering approaches.” The study links to research from Trend Micro that the Windows bug was being exploited as a zero-day by multiple government-backed hacking groups in North Korea, China, Russia and Iran — enabling widespread espionage and data theft activities. Arctic Wolf noted that the exploitation of the vulnerability was concerning because it showed that UNC6384 was able to adopt the vulnerability into its tool set just six months after it was publicly disclosed. The researchers warned that the timeline “suggests either direct monitoring of vulnerability disclosures with rapid development cycles, or potential pre-disclosure awareness through other intelligence channels.” PlugX allowed the hackers to establish long-term access to a victim’s system and enabled them to exfiltrate classified documents, monitor policy discussions in real time, surveil diplomatic calendars and travel plans, and collect credentials that would enable further access to diplomatic networks. The malware has been used in attacks since 2008 and remains a popular tool among Chinese espionage groups. It has evolved significantly since 2008 and several variations have been created, including versions known as Korplug, TIGERPLUG, and SOGU. Arctic Wolf found versions that have been developed and refined in the last six months. It enables threat actors to conduct keylogging, upload and download files,, establish persistence and closely monitor system functions. The latest version has been streamlined significantly, maintaining “essential functionality while dramatically reducing forensic footprint and analysis surface area,” Arctic Wolf said. According to the company, UNC6384 has ties to Mustang Panda — one of China’s most prolific espionage groups. Both groups share operational tools, targets, overlapping infrastructure and more. In January, the Justice Department removed PlugX from more than 4,000 U.S. computers in an operation aimed at stopping a Mustang Panda campaign. The action was part of a global effort to address the spread of PlugX, which had been found on nearly 100,000 devices in about 170 countries. Mustang Panda was previously accused by the European Union’s cybersecurity agency of targeting European businesses and organizations. The group was even seen targeting diplomatic entities in Russia. Their other victims include the African Union, several telecommunications companies, prime ministers across Asia, Myanmar’s president, Indonesia’s intelligence agency and more. Jonathan Greig is a Breaking News Reporter at Recorded Future News. Jonathan has worked across the globe as a journalist since 2014. Before moving back to New York City, he worked for news outlets in South Africa, Jordan and Cambodia. He previously covered cybersecurity at ZDNet and TechRepublic.
therecord.mediaOct 30, 2025extracted
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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.*
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Jul 28, 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.*
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Jul 31, 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.
3 shared
Aug 1, 2025
ReVault flaws let hackers bypass Windows login on Dell laptops
ControlVault3 firmware vulnerabilities impacting over 100 Dell laptop models can allow attackers to bypass Windows login and install malware that persists across system reinstalls. Dell ControlVault is a hardware-based security solution that stores passwords, biometric data, and security codes within firmware on a dedicated daughterboard, known as the Unified Security Hub (USH). The five vulnerabilities, reported by Cisco's Talos security division and dubbed "ReVault," affect both the ControlVault3 firmware and its Windows application programming interfaces (APIs) across Dell's business-focused Latitude and Precision laptop series. These devices are popular in cybersecurity, government, and industrial environments, where smartcards, fingerprints, and NFC are also commonly used for authentication. The complete list of ReVault vulnerabilities includes out-of-bounds flaws (CVE-2025-24311, CVE-2025-25050), an arbitrary free vulnerability (CVE-2025-25215), a stack overflow (CVE-2025-24922, and an unsafe deserialization issue (CVE-2025-24919) affecting ControlVault's Windows APIs. Dell has released security updates to address the ReVault flaws in the ControlVault3 driver and firmware between March and May. The full list of impacted models is available in Dell's security advisory. Windows login bypass and privilege escalation Chaining these vulnerabilities can allow attackers to gain arbitrary code execution on the firmware, potentially creating persistent implants that survive Windows reinstalls. They can also leverage physical access to bypass Windows login or escalate local user privileges to the administrator level. "A local attacker with physical access to a user's laptop can pry it open and directly access the USH board over USB with a custom connector," Cisco Talos said. "From there, all the vulnerabilities described previously become in-scope for the attacker without requiring the ability to log-in into the system or knowing a full-disk encryption password." Successful exploitation can also enable attackers to manipulate fingerprint authentication, forcing the targeted device to accept any fingerprint rather than only those of legitimate users. Talos recommends keeping systems updated through Windows Update or Dell's website, disabling unused security peripherals like fingerprint readers, smart card readers, and NFC readers, and disabling fingerprint login in high-risk situations. To mitigate some of the physical attacks, the researchers also suggested enabling chassis intrusion detection in computer BIOS settings to flag physical tampering attempts and Enhanced Sign-in Security (ESS) in Windows to detect inappropriate CV firmware. 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
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Aug 11, 2025
Microsoft Patches Over 100 Vulnerabilities
August 2025 Patch Tuesday forecast: Try, try again July turned into a surprisingly busy month. It started slowly with a fairly ‘calm’ Patch Tuesday as I forecasted in my last blog. Although there were 130 new CVEs addressed across all the Microsoft releases, there was only one publicly disclosed CVE, so the risk was low. But a short time later, two CVEs in SharePoint were reported exploited, and the month started to heat up with hotfixes near the end of the month. Mix in some security configuration issues with Microsoft Exchange Server and some major updates from Google and Apple, and the month ended with lots of activity. CISA flags SharePoint flaws as Microsoft issues new fixes It can take a few iterations to completely fix a vulnerability. Microsoft found this out with a recent round of SharePoint vulnerability fixes. Earlier this year in the Berlin Pwn2Own contest, a series of vulnerabilities called the ‘ToolShell’ chain were exploited and subsequently fixed in the Microsoft July 2025 Patch Tuesday updates. The key vulnerabilities a CVE-2025-49704 SharePoint Remote Code Execution Vulnerability and CVE-2025-49706 SharePoint Server Spoofing Vulnerability. Not long after this release, Microsoft, Google, and others reported these fixes had been bypassed and many organizations had been compromised. On July 19th Microsoft released an update with a more ‘hardened’ fix with associated vulnerabilities CVE-2025-53770 and CVE-2025-53771. There are separate releases for Microsoft SharePoint Server Subscription Edition, Microsoft SharePoint Server 2019 and Microsoft SharePoint Enterprise Server 2016. In addition to applying the updates, Microsoft recommends you rotate the associated machine keys on the impacted servers. There is reported ransomware that is taking advantage of this ToolShell attack chain and CISA has included them in their catalog of exploited vulnerabilities for immediate fix by federal agencies. Anticipate these hotfixes will be included in the August Patch Tuesday releases as well. Zero-Day in Chromium, dozens of Apple CVEs fixed in latest releases Microsoft issued CVE-2025-53786 to address security issues with respect to Microsoft Exchange Server in hybrid environments. This CVE ties together the April update and security hotfix with a series of instructions on securing on-premise Microsoft Exchange Server and Exchange Online. They share credentials and data such as calendars, email contact lists, etc. which can lead to compromise with little logging to show what happened. This Exchange Server blog, provides extensive details on the upcoming EOL of Exchange products as well as migration options to a more secure configuration. There are a few other major non-Microsoft updates to be aware of since last July 2025 Patch Tuesday. Google continues with weekly updates to the Chromium browser with a release on July 16th to address several vulnerabilities including zero-day CVE-2025-6558. This vulnerability allowed a remote attacker to potentially perform a sandbox escape. Apple also released a series of major updates for its operating systems and applications. Of note, from these updates include Ventura 13.7.7 with 41 CVEs, Sonoma 14.7.7 with 50 CVEs, Sequioa 15.6 with 89 CVEs, and Safari for Ventura and Sonoma with 17 CVEs fixed. August Patch Tuesday forecast We know SharePoint will receive some important updates this month and don’t forget there is more to do than just applying the updates and walking away – you need to consider updating your machine keys. Expect all the usual OS and app updates, but it’s been a while so may see a security fix in.NET framework or maybe SQL Server this month. Adobe continues with a steady stream of updates for the Creative Cloud suite of products so expect more this month with maybe Photoshop being the focus. Apple released their major updates on July 29th, and since we haven’t heard of any major issues, we should have a break for another month or two. Just make sure you have all the latest updates deployed. Google releases Chrome updates almost every Patch Tuesday but be aware they are often seen late in the day. The last set of security releases from Mozilla was July 22nd, so we are due for the Firefox and Thunderbird updates along with their ESR versions. Fixing vulnerabilities in software can often seem like plugging holes in a dam – just when you get one fixed, another leak appears. Microsoft found that out with these recent SharePoint vulnerabilities, but we’ve seen it before (remember Print NightMare) and we’ll see it again. Let’s just hope this time they don’t need to try, try again.
3 shared
Aug 13, 2025
Update Microsoft SharePoint ASAP | Kaspersky official blog
The recently disclosed critical Microsoft SharePoint vulnerability has been under exploitation as early as July 7, 2025, according to findings from Check Point Research. The cybersecurity company said it observed first exploitation attempts targeting an unnamed major Western government, with the activity intensifying on July 18 and 19, spanning government, telecommunications, and software sectors in North America and Western Europe. Check Point also said the exploitation efforts originated from three different IP addresses – 104.238.159[.]149, 107.191.58[.]76, and 96.9.125[.]147 – one of which was previously tied to the weaponization of security flaws in Ivanti Endpoint Manager Mobile (EPMM) appliances (CVE-2025-4427 and CVE-2025-4428). "We're witnessing an urgent and active threat: a critical zero-day in SharePoint on-prem is being exploited in the wild, putting thousands of global organizations at risk," Lotem Finkelstein, Director of Threat Intelligence at Check Point Research, told The Hacker News. "Our team has confirmed dozens of compromise attempts across government, telecom, and tech sectors since July 7. We strongly urge enterprises to update their security systems immediately – this campaign is both sophisticated and fast-moving." The attack chains have been observed leveraging CVE-2025-53770, a newly patched remote code execution flaw in SharePoint Server, and chaining it with CVE-2025-49706, a spoofing vulnerability that was patched by Microsoft as part of its July 2025 Patch Tuesday update, to gain initial access and escalate privileges. It's worth mentioning at this stage that there are two sets of vulnerabilities in SharePoint that have come to light this month - CVE-2025-49704 (CVSS score: 8.8) - Microsoft SharePoint Remote Code Execution Vulnerability (Fixed on July 8, 2025) CVE-2025-49706 (CVSS score: 6.5) - Microsoft SharePoint Server Spoofing Vulnerability (Fixed on July 8, 2025) CVE-2025-53770 (CVSS score: 9.8) - Microsoft SharePoint Server Remote Code Execution Vulnerability CVE-2025-53771 (CVSS score: 6.5) - Microsoft SharePoint Server Spoofing Vulnerability CVE-2025-49704 and CVE-2025-49706, collectively referred to as ToolShell, is an exploitation chain that can lead to remote code execution on SharePoint Server instances. They were originally disclosed by Viettel Cyber Security during the Pwn2Own 2025 hacking competition earlier this May. CVE-2025-53770 and CVE-2025-53771, which became public knowledge over the weekend, have been described as variants of CVE-2025-49704 and CVE-2025-49706, respectively, indicating that they are bypasses for the original fixes put in place by Microsoft earlier this month. This is evidenced by the fact that Microsoft acknowledged active attacks exploiting "vulnerabilities partially addressed by the July Security Update." The company also noted in its advisories that the updates for CVE-2025-53770 and CVE-2025-53771 include "more robust protections" than the updates for CVE-2025-49704 and CVE-2025-49706. However, it bears noting that CVE-2025-53771 has not been flagged by Redmond as actively exploited in the wild. "CVE-2025-53770 exploits a weakness in how Microsoft SharePoint Server handles the deserialization of untrusted data," Martin Zugec, technical solutions director at Bitdefender, said. "Attackers are leveraging this flaw to gain unauthenticated remote code execution." This, in turn, is achieved by deploying malicious ASP.NET web shells that programmatically extract sensitive cryptographic keys. These stolen keys are subsequently leveraged to craft and sign malicious __VIEWSTATE payloads, thereby establishing persistent access and enabling the execution of arbitrary commands on SharePoint Server. According to Bitdefender telemetry, in-the-wild exploitation has been detected in the United States, Canada, Austria, Jordan, Mexico, Germany, South Africa, Switzerland, and the Netherlands, suggesting widespread abuse of the flaw. Palo Alto Networks Unit 42, in its own analysis of the campaign, said it observed commands being run to execute a Base64-encoded PowerShell command, which creates a file at the location "C:\PROGRA~1\COMMON~1\MICROS~1\WEBSER~1\16\TEMPLATE\LAYOUTS\spinstall0.aspx" and then parses its content. "The spinstall0.aspx file is a web shell that can execute various functions to retrieve ValidationKeys, DecryptionKeys, and the CompatabilityMode of the server, which are needed to forge ViewState Encryption keys," Unit 42 said in a threat brief. In an advisory issued Monday, SentinelOne said it first detected exploitation on July 17, with the cybersecurity company identifying three "distinct attack clusters," including state-aligned threat actors, engaging in reconnaissance and early-stage exploitation activities. Targets of the campaigns include technology consulting, manufacturing, critical infrastructure, and professional services tied to sensitive architecture and engineering organizations. "The early targets suggest that the activity was initially carefully selective, aimed at organizations with strategic value or elevated access," researchers Simon Kenin, Jim Walter, and Tom Hegel said. Analysis of the attack activity has revealed the use of a password-protected ASPX web shell ("xxx.aspx") on July 18, 2025, at 9:58 a.m. GMT. The web shell supports three functions: Authentication via an embedded form, command execution via cmd.exe, and file upload. Subsequent exploitation efforts have been found to employ the "spinstall0.aspx" web shell to extract and expose sensitive cryptographic material from the host. Spinstall0.aspx is "not a traditional command web shell but rather a reconnaissance and persistence utility," the researchers explained. "This code extracts and prints the host's MachineKey values, including the ValidationKey, DecryptionKey, and cryptographic mode settings -- information critical for attackers seeking to maintain persistent access across load-balanced SharePoint environments or to forge authentication tokens." Unlike other web shells that are typically dropped on internet-exposed servers to facilitate remote access, spinstall0.aspx appears to be designed with the sole intention of gathering cryptographic secrets that could then be used to forge authentication or session tokens across SharePoint instances. These attacks, per CrowdStrike, commence with a specially crafted HTTP POST request to an accessible SharePoint server via the "/_layouts/15/ToolPane.aspx" endpoint that attempts to write spinstall0.aspx via PowerShell. The company said it blocked hundreds of exploitation attempts across more than 160 customer environments. SentinelOne also discovered a cluster dubbed "no shell" that took a "more advanced and stealthy approach" to other threat actors by opting for in-memory .NET module execution without dropping any payloads on disk. The activity originated from the IP address 96.9.125[.]147. "This approach significantly complicates detection and forensic recovery, underscoring the threat posed by fileless post-exploitation techniques," the company said, positing that it's either a "skilled red team emulation exercise or the work of a capable threat actor with a focus on evasive access and credential harvesting." It's currently not known who is behind the attack activity, although Google-owned Mandiant has attributed the early-exploitation to a China-aligned hacking group. Data from Censys shows that there are 9,762 on-premises SharePoint servers online, although it's currently not known if all of them are susceptible to the flaws. Given that SharePoint servers are a lucrative target for threat actors due to the nature of sensitive organizational data stored in them, it's essential that users move quickly to apply the fixes, rotate the keys, and restart the instances. "We assess that at least one of the actors responsible for the early exploitation is a China-nexus threat actor," Charles Carmakal, CTO, Mandiant Consulting at Google Cloud, said in a post on LinkedIn. "We're aware of victims in several sectors and global geographies. The activity primarily involved the theft of machine key material which could be used to access victim environments after the patch has been applied." (The story was updated after publication on July 23, 2025, to reflect the change in CVSS scores.)
3 shared
Jul 22, 2025