Detection rules › Sigma
Shell Execution via Flock - Linux
Detects the use of the "flock" command to execute a shell. Such behavior may be associated with privilege escalation, unauthorized command execution, or to break out from restricted environments.
MITRE ATT&CK coverage
| Tactic | Techniques |
|---|---|
| Discovery | T1083 File and Directory Discovery |
Event coverage
| Provider | Event |
|---|---|
| Sysmon-for-Linux | Event ID 1 |
Rule body yaml
title: Shell Execution via Flock - Linux
id: 4b09c71e-4269-4111-9cdd-107d8867f0cc
status: test
description: |
Detects the use of the "flock" command to execute a shell. Such behavior may be associated with privilege escalation, unauthorized command execution, or to break out from restricted environments.
references:
- https://gtfobins.github.io/gtfobins/flock/#shell
- https://www.elastic.co/guide/en/security/current/linux-restricted-shell-breakout-via-linux-binary-s.html
author: Li Ling, Andy Parkidomo, Robert Rakowski, Blake Hartstein (Bloomberg L.P.)
date: 2024-09-02
tags:
- attack.discovery
- attack.t1083
logsource:
category: process_creation
product: linux
detection:
selection_img:
Image|endswith: '/flock'
CommandLine|contains: ' -u '
selection_cli:
CommandLine|contains:
- '/bin/bash'
- '/bin/dash'
- '/bin/fish'
- '/bin/sh'
- '/bin/zsh'
condition: all of selection_*
falsepositives:
- Unknown
level: high
Stages and Predicates
Stage 0: condition
all of selection_*Stage 1: selection_img
selection_img:
Image|endswith: '/flock'
CommandLine|contains: ' -u '
Stage 2: selection_cli
selection_cli:
CommandLine|contains:
- '/bin/bash'
- '/bin/dash'
- '/bin/fish'
- '/bin/sh'
- '/bin/zsh'
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 |
|---|---|---|
CommandLine | match |
|
Image | ends_with |
|