Detection rules › Sigma
Katz Stealer Suspicious User-Agent
Detects network connections with a suspicious user-agent string containing "katz-ontop", which may indicate Katz Stealer activity.
MITRE ATT&CK coverage
| Tactic | Techniques |
|---|---|
| Command & Control | T1071.001 Application Layer Protocol: Web Protocols |
Rule body 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
Stages and Predicates
Stage 0: condition
selectionStage 1: selection
selection:
user_agent|contains: 'katz-ontop'
Indicators
Each row is a field, operator, and value that the rule matches. The corpus column counts how many other rules in the catalog look for the same combination: high numbers point to widely-used, community-vetted indicators. Blank or 1 shows that the indicator is specific to this rule.
| Field | Kind | Values |
|---|---|---|
user_agent | match |
|