Sigma rule: Suspicious Serv-U Process Pattern

Rule

Title

Suspicious Serv-U Process Pattern

Status

test

Level

high

Author

Florian Roth (Nextron Systems)

Date

2021-07-14

Modified

2022-07-14

File

rules/windows/process_creation/proc_creation_win_servu_susp_child_process.yml

Commit

ccbb0369507f796db0b0ae6854c8a2be471b9d84

Detects a suspicious process pattern which could be a sign of an exploited Serv-U service

Log source

product

windows

category

process_creation

Detection

selection:
    ParentImage|endswith: '\Serv-U.exe'
    Image|endswith:
        - '\cmd.exe'
        - '\powershell.exe'
        - '\pwsh.exe'
        - '\wscript.exe'
        - '\cscript.exe'
        - '\sh.exe'
        - '\bash.exe'
        - '\schtasks.exe'
        - '\regsvr32.exe'
        - '\wmic.exe'  # https://app.any.run/tasks/c903e9c8-0350-440c-8688-3881b556b8e0/
        - '\mshta.exe'
        - '\rundll32.exe'
        - '\msiexec.exe'
        - '\forfiles.exe'
        - '\scriptrunner.exe'
condition: selection

False positives (as the rule lists them)

• Legitimate uses in which users or programs use the SSH service of Serv-U for remote command execution

Tags

• attack.credential-access
• attack.t1555
• cve.2021-35211

CVEs this rule names

• CVE-2021-35211

MITRE ATT&CK ids this rule names

• T1555

References

• https://www.microsoft.com/security/blog/2021/07/13/microsoft-discovers-threat-actor-targeting-solarwinds-serv-u-software-with-0-day-exploit/

Read on 2026-11-03T00:58:21.399Z under licence sigma-drl-1.1@d5f4c36a from https://github.com/SigmaHQ/sigma/blob/ccbb0369507f796db0b0ae6854c8a2be471b9d84/rules/windows/process_creation/proc_creation_win_servu_susp_child_process.yml