Linux: System Shell Spawned by Celery Worker Python Process
Flags Linux instances where a Celery worker’s Python process spawns a system shell interpreter.
- Product
- linux
- Category
- process_creation
- Author
- Jennifer Batina (SigmaHQ), DRL 1.1
- Published
- 2026-10-17
- Updated
- 2026-10-17
ATT&CK techniques
ExecutionRecon
Resource Dev
Initial Access
Execution
Persistence
Priv Esc
Defense Evasion
Cred Access
Discovery
Lateral Movement
Collection
C2
Exfiltration
Impact
What it detects
This rule identifies process creation events where a system shell interpreter (e.g., sh/bash/dash/busybox variants) is spawned directly by a Celery-related worker process. Such direct shell execution from a Python/Celery task can indicate unsafe handling of task input leading to command execution. The detection relies on Linux process creation telemetry, matching shell executable paths and parent process image/command line details indicating Celery and Python origins.
Reporting behind it
- docs.celeryq.devhttps://docs.celeryq.dev/en/stable/userguide/tasks.html
- genai.owasp.orghttps://genai.owasp.org/llmrisk/llm01-prompt-injection/
- labs.cloudsecurityalliance.orghttps://labs.cloudsecurityalliance.org/research/csa-research-note-promptware-c2-agent-exploitation-20260406/
- nvd.nist.govhttps://nvd.nist.gov/vuln/detail/CVE-2021-23727
- owasp.orghttps://owasp.org/www-project-top-10-for-large-language-model-applications/
- security.snyk.iohttps://security.snyk.io/vuln/SNYK-PYTHON-CELERY-2314953
- snyk.iohttps://snyk.io/blog/python-rce-vulnerability/
- unit42.paloaltonetworks.comhttps://unit42.paloaltonetworks.com/ai-agent-prompt-injection/
- microsoft.comhttps://www.microsoft.com/en-us/security/blog/2026/05/07/prompts-become-shells-rce-vulnerabilities-ai-agent-frameworks
- github.comhttps://github.com/SigmaHQ/sigma/blob/master/rules/linux/process_creation/proc_creation_lnx_celery_worker_shell_spawn.yml
Detection content is published as a reviewed draft. Tune thresholds and exclusions against your own telemetry before enabling this rule for alerting.
title: "Linux: System Shell Spawned by Celery Worker Python Process"
id: ae77f69c-b5e0-4abc-b102-acfa72fbcb87
status: experimental
description: This rule identifies process creation events where a system shell interpreter (e.g., sh/bash/dash/busybox variants) is spawned directly by a Celery-related worker process. Such direct shell execution from a Python/Celery task can indicate unsafe handling of task input leading to command execution. The detection relies on Linux process creation telemetry, matching shell executable paths and parent process image/command line details indicating Celery and Python origins.
references:
- https://docs.celeryq.dev/en/stable/userguide/tasks.html
- https://genai.owasp.org/llmrisk/llm01-prompt-injection/
- https://labs.cloudsecurityalliance.org/research/csa-research-note-promptware-c2-agent-exploitation-20260406/
- https://nvd.nist.gov/vuln/detail/CVE-2021-23727
- https://owasp.org/www-project-top-10-for-large-language-model-applications/
- https://security.snyk.io/vuln/SNYK-PYTHON-CELERY-2314953
- https://snyk.io/blog/python-rce-vulnerability/
- https://unit42.paloaltonetworks.com/ai-agent-prompt-injection/
- https://www.microsoft.com/en-us/security/blog/2026/05/07/prompts-become-shells-rce-vulnerabilities-ai-agent-frameworks
- https://github.com/SigmaHQ/sigma/blob/master/rules/linux/process_creation/proc_creation_lnx_celery_worker_shell_spawn.yml
author: Jennifer Batina, Huntrule Team
date: 2026-10-17
tags:
- attack.execution
- attack.t1059.004
logsource:
category: process_creation
product: linux
detection:
selection_img:
Image|endswith:
- /ash
- /bash
- /busybox
- /csh
- /dash
- /fish
- /ksh
- /sh
- /tcsh
- /zsh
ParentCommandLine|contains: celery
selection_parent:
- ParentImage|endswith:
- /python
- /python3
- ParentImage|contains: /python3.
condition: all of selection_*
falsepositives:
- Legacy or custom administrative tasks deliberately hardcoded with shell=True or os.system execution inside Celery task functions.
- Media processing, deployment, or reporting pipelines that intentionally shell out to external tools (e.g. ffmpeg, git) from within a task.
level: medium
license: DRL-1.1
related:
- id: 904f6442-3b57-4b3f-987c-1559f58ce8d8
type: derived