Sigma rule: Serv-U Exploitation CVE-2021-35211 by DEV-0322

A detection rule from the SigmaHQ repository, shown as its author published it. Dataset version ref-9259e35932de, updated 2022-12-18T00:00:00.000Z.

Rule

Title
Serv-U Exploitation CVE-2021-35211 by DEV-0322
Status
test
Level
critical
Author
Florian Roth (Nextron Systems)
Date
2021-07-14
Modified
2022-12-18
File
rules-emerging-threats/2021/Exploits/CVE-2021-35211/proc_creation_win_exploit_cve_2021_35211_servu.yml
Commit
ccbb0369507f796db0b0ae6854c8a2be471b9d84

Detects patterns as noticed in exploitation of Serv-U CVE-2021-35211 vulnerability by threat group DEV-0322

Log source

product
windows
category
process_creation

Detection

selection_whoami:
    CommandLine|contains: 'whoami'
selection_cmd_1:
    CommandLine|contains:
        - './Client/Common/'
        - '.\Client\Common\'
selection_cmd_2:
    CommandLine|contains: 'C:\Windows\Temp\Serv-U.bat'
condition: selection_whoami and 1 of selection_cmd*

False positives (as the rule lists them)

  • Unlikely

Tags

  • attack.persistence
  • attack.t1136.001
  • cve.2021-35211
  • detection.emerging-threats

CVEs this rule names

MITRE ATT&CK ids this rule names

References

Read on 2026-11-03T00:58:21.399Z under licence sigma-drl-1.1@d5f4c36a from https://github.com/SigmaHQ/sigma/blob/ccbb0369507f796db0b0ae6854c8a2be471b9d84/rules-emerging-threats/2021/Exploits/CVE-2021-35211/proc_creation_win_exploit_cve_2021_35211_servu.yml

Sources and licences

  • SigmaHQ

    "Serv-U Exploitation CVE-2021-35211 by DEV-0322" by Florian Roth (Nextron Systems) (SigmaHQ). Rule: https://github.com/SigmaHQ/sigma/blob/ccbb0369507f796db0b0ae6854c8a2be471b9d84/rules-emerging-threats/2021/Exploits/CVE-2021-35211/proc_creation_win_exploit_cve_2021_35211_servu.yml.
    Licensed under the Detection Rule License (DRL) 1.1: https://github.com/SigmaHQ/Detection-Rule-License

    Detection Rule License (DRL) 1.1

Cite this page

Dragons Eye Ransomware Tracker, "Sigma rule: Serv-U Exploitation CVE-2021-35211 by DEV-0322",
entity page, dataset version ref-9259e35932de, updated 2022-12-18T00:00:00.000Z,
https://ransomware-tracker.com/detections/sigma/75578840-9526-4b2a-9462-af469a45e767 (accessed 2026-11-03).
Underlying source: SigmaHQ rule 75578840-9526-4b2a-9462-af469a45e767, commit ccbb0369507f796db0b0ae6854c8a2be471b9d84.

Pages change. The dataset version identifies the data, but no archive of old versions is kept, so this citation cannot be replayed later.