Emerging Threathighexperimental

Potential SharePoint ToolShell CVE-2025-53770 Exploitation Indicators

Detects potential exploitation of CVE-2025-53770 by identifying indicators such as suspicious command lines discovered in Post-Exploitation activities. CVE-2025-53770 is a zero-day vulnerability in SharePoint that allows remote code execution.

Convert In Phoenix Studio

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

Launch

Swachchhanda Shrawan Poudel (Nextron Systems)Created Mon Jul 217477881c-ec3b-49d6-aced-7255944e5c592025

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_img:
        ParentImage|endswith: '\w3wp.exe'
    selection_encoded_aspx:
        - CommandLine|wide|base64offset|contains: 'spinstall0.aspx'
        - CommandLine|base64|contains: 'spinstall0.aspx'
    selection_encoded_path:
        CommandLine|wide|base64offset|contains:
            - ':\PROGRA~1\COMMON~1\MICROS~1\WEBSER~1\15\TEMPLATE\LAYOUTS'
            - ':\PROGRA~1\COMMON~1\MICROS~1\WEBSER~1\16\TEMPLATE\LAYOUTS'
            - ':\Program Files\Common Files\Microsoft Shared\Web Server Extensions\15\TEMPLATE\LAYOUTS'
            - ':\Program Files\Common Files\Microsoft Shared\Web Server Extensions\16\TEMPLATE\LAYOUTS'
    selection_ioc:
        CommandLine|contains:
            - '-EncodedCommand JABiAGEAcwBlADYANABTAHQAcgBpAG4AZwAgAD0'
            - 'TEMPLATE\LAYOUTS\spinstall0.aspx'
    condition: (selection_img and 1 of selection_encoded_*) or selection_ioc