Apache Airflow is a popular open-source platform designed to programmatically manage, monitor, and execute complex workflows. Recently, an issue has been reported under the identifier CVE-2022-43982, which could potentially make earlier versions of Airflow (prior to 2.4.2) vulnerable to cross-site scripting (XSS) attacks. The vulnerability affects the "Trigger DAG with config" screen in those versions. In this post, we explore the details of this security threat, examine a code snippet showcasing the exploit, and discuss potential mitigations. We also provide references to the original sources that help with the further understanding of this issue.

Exploit Details

The XSS vulnerability arises due to the presence of an unsanitized query parameter called origin within the "Trigger DAG with config" screen. An attacker could exploit this vulnerability by crafting a malicious URL containing a specially-formatted value for the origin query parameter. This parameter could contain XSS payloads that will be executed in the context of the victim's browser when the URL is visited.

Here is a sample code snippet that demonstrates the nature of this vulnerability

@app.route('/trigger_dag')
def trigger_dag():
    origin = request.args.get('origin', '')
    ...
    return render_template('trigger_dag.html', origin=origin)

In the above code, we see that the value of the origin parameter is fetched directly from the request and used without proper sanitization. This makes it possible for an attacker to inject malicious code in the form of an XSS payload into the user's browser.

An example of a URL that exploits the vulnerability could look like

https://example.com/trigger_dag?origin=<script>alert('XSS');</script>;

In this case, <script>alert('XSS');</script> would be executed as JavaScript on the victim's browser, causing an alert pop-up to appear with the message "XSS." This is just a simple example of the type of payloads that might be executed, and in reality, attacks could potentially result in more advanced XSS payloads leading to sensitive data theft, session hijacking, or other malicious activities.

Mitigation

The recommended mitigation for this vulnerability is to update your Apache Airflow instance to version 2.4.2 or later. In these versions, the issue has been resolved by properly sanitizing the origin parameter before rendering it in the HTML template. If you are unable to update your Apache Airflow instance, you should consider applying custom sanitization to the origin parameter as a temporary workaround. The best practice would be to urlencode the parameter before rendering it, like so:

from urllib.parse import quote 

@app.route('/trigger_dag')
def trigger_dag():
    origin = quote(request.args.get('origin', ''))
    ...
    return render_template('trigger_dag.html', origin=origin)

This would serve to protect your Airflow instance from potential XSS attacks that exploit this vulnerability.

For more information regarding this security issue, we recommend examining the following sources

1. Official Apache Airflow Security Documentation
2. CVE-2022-43982 Detail - National Vulnerability Database

In conclusion, the CVE-2022-43982 vulnerability is a serious issue affecting Apache Airflow versions prior to 2.4.2. The exploitation of this vulnerability allows for XSS attacks via the origin query argument in the "Trigger DAG with config" screen. The recommended solution is to update the software to the latest version, which mitigates the vulnerability by appropriately sanitizing the said query parameter.

Timeline

Published on: 11/02/2022 12:15:00 UTC
Last modified on: 11/03/2022 13:52:00 UTC