All news with #active exploitation tag

🔔 Unit 42 reports active exploitation of multiple on‑premises SharePoint vulnerabilities collectively dubbed ToolShell, enabling unauthenticated remote code execution, authentication bypass, and path traversal. Activity observed from mid‑July 2025 includes web shell deployment, theft of ASP.NET MachineKeys and ViewState material, and delivery of the 4L4MD4R ransomware in at least one chain. Organizations with internet‑exposed SharePoint servers should assume potential compromise and follow containment, patching, cryptographic rotation, and incident response guidance immediately.

🛡️ ESET's research details active exploitation of two zero-day vulnerabilities—CVE-2025-53770 and CVE-2025-53771—against on-premises Microsoft SharePoint servers in a campaign dubbed ToolShell. The company reports global impact, with the United States responsible for 13.3% of observed attacks. Organizations should immediately prioritize patching affected servers, apply vendor mitigations, tighten access controls and monitoring, and review logs for indicators of compromise. Watch the accompanying video featuring ESET Chief Security Evangelist Tony Anscombe and consult the full blogpost for technical detail.

🔒 Microsoft and ESET reported active exploitation of a SharePoint Server vulnerability cluster called ToolShell, comprising CVE-2025-53770 (remote code execution) and CVE-2025-53771 (server spoofing). Attacks began on July 17, 2025, and target on-prem SharePoint Subscription Edition, SharePoint 2019 and SharePoint 2016; SharePoint Online is not affected. Operators deployed webshells — notably spinstall0.aspx (detected as MSIL/Webshell.JS) and several ghostfile*.aspx samples — to bypass MFA/SSO, exfiltrate data and move laterally across integrated Microsoft services. Microsoft and ESET confirmed patches were released on July 22, and ESET published IoCs and telemetry to assist defenders.

🔒 Microsoft warns of active attacks against on-premises SharePoint Server and has issued security updates that fully remediate CVE-2025-53770 and CVE-2025-53771 for supported versions. Customers should apply the published updates immediately, enable AMSI with HTTP request body scanning where available, and deploy endpoint protections such as Microsoft Defender for Endpoint. After patching, rotate ASP.NET machine keys and restart IIS to complete mitigation; SharePoint Online is not affected.