Sigma rule: CobaltStrike Malformed UAs in Malleable Profiles

A detection rule from the SigmaHQ repository, shown as its author published it. Dataset version ref-7076df0d3c44, updated 2024-02-15T00:00:00.000Z.

SigmaHQ marks this rule as deprecated.

Rule

Title
CobaltStrike Malformed UAs in Malleable Profiles
Status
deprecated
Level
critical
Author
Florian Roth (Nextron Systems)
Date
2021/05/06
Modified
2024/02/15
File
deprecated/web/proxy_cobalt_malformed_uas.yml
Commit
ccbb0369507f796db0b0ae6854c8a2be471b9d84

Detects different malformed user agents used in Malleable Profiles used with Cobalt Strike

Log source

category
proxy

Detection

selection1:
    c-useragent:
        - 'Mozilla/4.0 (compatible; MSIE 6.0;Windows NT 5.1)'
        - 'Mozilla/4.0 (compatible; MSIE 7.0; Windows NT 6.1; WOW64; Trident/4.0; SLCC2; .NET CLR 3.0.30729; .NET4.0C; .NET4.0E )'
        - 'Mozilla/5.0 (Windows; U; MSIE 7.0; Windows NT 5.2) Java/1.5.0_08'
selection2:
    c-useragent|endswith: '; MANM; MANM)'
condition: 1 of selection*

False positives (as the rule lists them)

  • Unknown

Tags

  • attack.defense_evasion
  • attack.command_and_control
  • attack.t1071.001

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/deprecated/web/proxy_cobalt_malformed_uas.yml

Sources and licences

  • SigmaHQ

    "CobaltStrike Malformed UAs in Malleable Profiles" by Florian Roth (Nextron Systems) (SigmaHQ). Rule: https://github.com/SigmaHQ/sigma/blob/ccbb0369507f796db0b0ae6854c8a2be471b9d84/deprecated/web/proxy_cobalt_malformed_uas.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: CobaltStrike Malformed UAs in Malleable Profiles",
entity page, dataset version ref-7076df0d3c44, updated 2024-02-15T00:00:00.000Z,
https://ransomware-tracker.com/detections/sigma/41b42a36-f62c-4c34-bd40-8cb804a34ad8 (accessed 2026-11-03).
Underlying source: SigmaHQ rule 41b42a36-f62c-4c34-bd40-8cb804a34ad8, 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.