Sigma Rule Library

Katz Stealer Suspicious User-Agent

Detects network connections with a suspicious user-agent string containing "katz-ontop", which may indicate Katz Stealer activity.

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Detection logic

selection

user_agent|contains: katz-ontop

Condition

selection

Raw YAML

title: Katz Stealer Suspicious User-Agent
id: 834c6d2f-5e98-4b2a-b453-0c4f234afedd
status: experimental
description: |
    Detects network connections with a suspicious user-agent string containing "katz-ontop", which may indicate Katz Stealer activity.
references:
    - Internal Research
author: Swachchhanda Shrawan Poudel (Nextron Systems)
date: 2025-05-22
tags:
    - attack.command-and-control
    - attack.t1071.001
    - detection.emerging-threats
logsource:
    product: zeek
    service: http
detection:
    selection:
        user_agent|contains: 'katz-ontop'
    condition: selection
falsepositives:
    - Unlikely
level: high

False positives

  • Unlikely

References

  • Internal Research

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