GRAYRABBIT

Multiple threat actors are exploiting a new vulnerability chain involving flaws in Google Chrome (CVE-2026-85046, CVE-2026-87491) and Microsoft Windows (CVE-2026-85880) to deploy an undocumented exploit kit called BlueMoon. The campaigns, primarily attributed to China-aligned groups, have targeted fewer than 20 organizations globally. Separately, a zero-click worm dubbed WeWorm exploits a vulnerability in WeChat (patched in August 2026) to hijack accounts and spread via incoming calls on Android and iOS without user interaction, requiring only that the attacker be on the victim's friends list. Additionally, hackers are deploying a fileless Linux rootkit on compromised F5 BIG-IP APM devices, leveraging CVE-2025-53521 to inject a web shell into memory via PHP eval() calls, tracked by ESET as PoisonedRefresh.

Threat actors associated with the China-aligned UNC3569 group are actively exploiting a critical remote code execution vulnerability, CVE-2026-51990, in Tencent's Sogou Input Method for Windows to deploy the GrayRabbit backdoor. The attack chain begins with a maliciously crafted sgbiz: URI that triggers command-line argument injection, leading to unvalidated execution in the SGMyInput.exe process. This allows loading of an attacker-controlled URL in an outdated, unsandboxed Chromium-based webview, which then exploits known browser flaws to achieve code execution and deploy the modular GrayRabbit malware. The malware supports remote command execution, file transfers, reverse shells, and reflective plugin loading, with its C2 configuration RC4-encoded.