Sigma rule: Shell Execution via Flock - Linux

Rule

Title

Shell Execution via Flock - Linux

Status

test

Level

high

Author

Li Ling, Andy Parkidomo, Robert Rakowski, Blake Hartstein (Bloomberg L.P.)

Date

2024-09-02

File

rules/linux/process_creation/proc_creation_lnx_flock_shell_execution.yml

Commit

ccbb0369507f796db0b0ae6854c8a2be471b9d84

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.

Log source

product

linux

category

process_creation

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_*

False positives (as the rule lists them)

• Unknown

Tags

• attack.discovery
• attack.t1083

MITRE ATT&CK ids this rule names

• T1083

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

Read on 2026-11-03T00:58:21.399Z under licence sigma-drl-1.1@d5f4c36a from https://github.com/SigmaHQ/sigma/blob/ccbb0369507f796db0b0ae6854c8a2be471b9d84/rules/linux/process_creation/proc_creation_lnx_flock_shell_execution.yml