Chinese Threat Actors Exploit ToolShell SharePoint Flaw Weeks After Microsoft's July Patch
Vulnerabilities mentionedAll →
| CVE | Vulnerability | CVSS | EPSS | Flags | Affected | Exposure | Published |
|---|---|---|---|---|---|---|---|
| CVE-2021-36942 | Unauthenticated LSA Spoofing (PetitPotam NTLM Relay) in Microsoft Windows CVE-2021-36942 is a spoofing flaw in the Windows Local Security Authority (LSA), widely known as "PetitPotam," that lets an unauthenticated network attacker trick a Windows host into authenticating with NTLM to a machine the attacker controls. It is triggered remotely with no privileges and no user interaction (CVSS 3.1 AV:N/AC:L/PR:N/UI:N) by sending crafted requests that coerce the target system to authenticate. By relaying that coerced authentication to other services, an attacker can impersonate the machine — most critically a domain controller — and escalate toward domain-administrator access, producing a high confidentiality impact. All listed Windows Server releases are affected, with domain controllers and certificate-services servers as the highest-value targets. The flaw is actively exploited in the wild: it was added to CISA's KEV on 2021-11-03 with known ransomware use (LockFile and Babuk campaigns chained it with Exchange flaws), and Microsoft has released Windows updates to address it. Do: Apply Microsoft's Windows updates per vendor instructions, prioritizing domain controllers and servers running Active Directory Certificate Services. As interim hardening, require SMB signing and restrict NTLM authentication per Microsoft guidance, and review authentication logs for unexpected NTLM connections from domain controllers to certificate-services endpoints. | 7.5 | 66% | KEV ransomware PoC |
| massmillions of Windows Server deployments; hundreds of thousands of SMB-exposed hosts in public internet scans | |
| CVE-2025-49704 +1 in the same advisory: …49706 | Authenticated Code Injection RCE in Microsoft SharePoint CVE-2025-49704 is a code injection vulnerability (CWE-94) in Microsoft SharePoint that allows an authorized (authenticated) attacker to execute arbitrary code on the server over the network, by sending requests whose attacker-controlled input SharePoint executes as code. It can be chained with CVE-2025-49706, and Microsoft subsequently issued CVE-2025-53770 as a patch bypass of the original CVE-2025-49704 fix, meaning the CVE-2025-53770 updates provide stronger protection and should be treated as the definitive remediation. Successful exploitation yields remote code execution on the SharePoint server, and CISA added the flaw to the KEV on 2025-07-22 with known ransomware use. Organizations running on-premises SharePoint Server are affected; CISA directs owners of public-facing servers running EOL/EOS versions (SharePoint Server 2013 and earlier) to disconnect them, and operators of supported versions to apply the CISA and vendor mitigations and updates, with cloud SharePoint services governed by BOD 22-01. Exploitation is confirmed in the wild and EPSS assigns a 100% probability of exploitation within 30 days (top percentile), although no public proof-of-concept code is documented. Do: Apply Microsoft's SharePoint Server updates for CVE-2025-53770, which supersede the original CVE-2025-49704 fixes with more robust protection, prioritizing internet-facing servers. Disconnect public-facing SharePoint servers running EOL/EOS versions (SharePoint Server 2013 and earlier), and for supported versions follow the CISA and vendor mitigations, with cloud services handled per BOD 22-01. Because in-the-wild exploitation and ransomware use are confirmed, hunt for indicators of compromise and ransomware activity on exposed SharePoint servers. | 8.8 group max | 100% | KEV ransomware |
| masstens of thousands of internet-exposed SharePoint servers per public scans, within a total on-premises install base plausibly exceeding 100,000 deployments… | |
| CVE-2025-53770 | Unauthenticated Deserialization RCE in Microsoft SharePoint Server on-premises CVE-2025-53770 is a deserialization of untrusted data vulnerability (CWE-502) in Microsoft SharePoint Server on-premises that allows an unauthorized attacker to execute code over a network. It is triggered when the server deserializes attacker-controlled data, can be chained with CVE-2025-53771, and it bypasses the fixes issued for CVE-2025-49704, meaning the earlier patches are insufficient. Successful exploitation yields remote code execution on the SharePoint server, and ransomware operators are known to be using it. Any organization running SharePoint Server on-premises is affected, particularly internet-facing deployments and end-of-life versions such as SharePoint Server 2013 and earlier that can no longer be patched. The flaw is being actively exploited — it was added to CISA's KEV on 2025-07-20 with known ransomware use — and EPSS assigns it a 100% probability of exploitation within 30 days. Do: Apply Microsoft's updated SharePoint Server security updates that fix CVE-2025-53770 — these include more robust protection than the earlier CVE-2025-49704 updates — and ensure the companion CVE-2025-53771 is also addressed, following CISA and vendor mitigation instructions for supported versions. Disconnect public-facing SharePoint Server 2013 or earlier (EOL/EOS) instances, minimize internet exposure of supported servers, and hunt for signs of compromise given the known ransomware exploitation. | 9.8 | 100% | KEV ransomware PoC ×3 |
| mass≈25,000–100,000 internet-exposed on-premises SharePoint servers (public internet-wide scans); total on-prem installed base plausibly >1M users |
Full article489 words · extracted from thehackernews.com · click to collapse
Ravie LakshmananOct 22, 2025Cyber Espionage / Vulnerability
Threat actors with ties to China exploited the ToolShell security vulnerability in Microsoft SharePoint to breach a telecommunications company in the Middle East after it was publicly disclosed and patched in July 2025.
Also targeted were government departments in an African country, as well as government agencies in South America, a university in the U.S., as well as likely a state technology agency in an African country, a government department in the Middle East, and a finance company in a European country.
According to Broadcom's Symantec Threat Hunter Team, the attacks involved the exploitation of CVE-2025-53770, a now-patched security flaw in on-premise SharePoint servers that could be used to bypass authentication and achieve remote code execution.
CVE-2025-53770, assessed to be a patch bypass for CVE-2025-49704 and CVE-2025-49706, has been weaponized as a zero-day by three Chinese threat groups, including Linen Typhoon (aka Budworm), Violet Typhoon (aka Sheathminer), and Storm-2603, the latter of which is linked to the deployment of Warlock, LockBit, and Babuk ransomware families in recent months.
However, the latest findings from Symantec indicate that a much wider range of Chinese threat actors have abused the vulnerability. This includes the Salt Typhoon (aka Glowworm) hacking group, which is said to have leveraged the ToolShell flaw to deploy tools like Zingdoor, ShadowPad, and KrustyLoader against the telecom entity and the two government bodies in Africa.
KrustyLoader, first detailed by Synacktiv in January 2024, is a Rust-based loader previously put to use by a China-nexus espionage group dubbed UNC5221 in attacks exploiting flaws in Ivanti Endpoint Manager Mobile (EPMM) and SAP NetWeaver.
The attacks aimed at government agencies in South America and a university in the U.S., on the other hand, involved the use of unspecified vulnerabilities to obtain initial access, followed by the exploitation of SQL servers and Apache HTTP servers running the Adobe ColdFusion software to deliver the malicious payloads using DLL side-loading techniques.
In some of the incidents, the attackers have been observed executing an exploit for CVE-2021-36942 (aka PetitPotam) for privilege escalation and domain compromise, along with a number of readily available and living-off-the-land (LotL) tools to facilitate scanning, file download, and credential theft on the infected systems.
"There is some overlap in the types of victims and some of the tools used between this activity and activity previously attributed to Glowworm," Symantec said. "However, we do not have sufficient evidence to conclusively attribute this activity to one specific group, though we can say that all evidence points to those behind it being China-based threat actors."
"The activity carried out on targeted networks indicates that the attackers were interested in stealing credentials and in establishing persistent and stealthy access to victim networks, likely for the purpose of espionage."
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