Chinese Threat Actors Exploit ToolShell SharePoint Flaw Weeks After Microsoft's July Patch
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.
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 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 two government bodies in Africa.
In some 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.