Arbitrary File Write via Archive Extraction (Zip Slip) Affecting rasa package, versions [,2.8.10)


Severity

Recommended
0.0
high
0
10

CVSS assessment made by Snyk's Security Team. Learn more

Threat Intelligence

EPSS
0.06% (27th percentile)

Do your applications use this vulnerable package?

In a few clicks we can analyze your entire application and see what components are vulnerable in your application, and suggest you quick fixes.

Test your applications
  • Snyk IDSNYK-PYTHON-RASA-1766497
  • published22 Oct 2021
  • disclosed22 Oct 2021
  • creditUnknown

Introduced: 22 Oct 2021

CVE-2021-41127  (opens in a new tab)
CWE-29  (opens in a new tab)

How to fix?

Upgrade rasa to version 2.8.10 or higher.

Overview

rasa is an Open source machine learning framework to automate text- and voice-based conversations: NLU, dialogue management, connect to Slack, Facebook, and more - Create chatbots and voice assistants

Affected versions of this package are vulnerable to Arbitrary File Write via Archive Extraction (Zip Slip) via the functionality that loads a trained model tar.gz file which allows a malicious actor to craft a model.tar.gz file which can overwrite or replace bot files in the bot directory.

For users unable to update: ensure that users do not upload untrusted model files, and restrict CLI or API endpoint access where a malicious actor could target a deployed Rasa instance.

Details

It is exploited using a specially crafted zip archive, that holds path traversal filenames. When exploited, a filename in a malicious archive is concatenated to the target extraction directory, which results in the final path ending up outside of the target folder. For instance, a zip may hold a file with a "../../file.exe" location and thus break out of the target folder. If an executable or a configuration file is overwritten with a file containing malicious code, the problem can turn into an arbitrary code execution issue quite easily.

The following is an example of a zip archive with one benign file and one malicious file. Extracting the malicous file will result in traversing out of the target folder, ending up in /root/.ssh/ overwriting the authorized_keys file:


+2018-04-15 22:04:29 ..... 19 19 good.txt

+2018-04-15 22:04:42 ..... 20 20 ../../../../../../root/.ssh/authorized_keys

References

CVSS Scores

version 3.1