Emerging Threathighstable

Potential CVE-2021-26857 Exploitation Attempt

Detects possible successful exploitation for vulnerability described in CVE-2021-26857 by looking for | abnormal subprocesses spawning by Exchange Server's Unified Messaging service

Convert In Phoenix Studio

Open this Sigma rule in the converter with the YAML preloaded and ready for backend selection.

Launch

Bhabesh RajCreated Wed Mar 03Updated Tue Feb 07cd479ccc-d8f0-4c66-ba7d-e06286f3f8872021

Emerging Threat

Active Threat

Developed to detect an active or emerging threat. Prioritize investigation of any alerts and correlate with threat intelligence.

Log Source

WindowsProcess Creation

ProductWindows← raw: windows

CategoryProcess Creation← raw: process_creation

Events generated when a new process is spawned on the system. Covers command-line arguments, parent/child relationships, and process metadata.

Detection Logic

detection:
    selection:
        ParentImage|endswith: '\UMWorkerProcess.exe'
    filter:
        Image|endswith:
            - 'wermgr.exe'
            - 'WerFault.exe'
    condition: selection and not filter