Arbitrary File Write via Archive Extraction (Zip Slip) Affecting tensorflow package, versions [,2.12.0rc1)


Severity

Recommended
0.0
critical
0
10

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

Threat Intelligence

Exploit Maturity
Proof of concept
EPSS
0.19% (58th percentile)

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  • Snyk IDSNYK-PYTHON-TENSORFLOW-1315149
  • published23 Jul 2021
  • disclosed30 Jun 2021
  • creditUnknown

Introduced: 30 Jun 2021

CVE-2021-35958  (opens in a new tab)
CWE-29  (opens in a new tab)

How to fix?

Upgrade tensorflow to version 2.12.0rc1 or higher.

Overview

tensorflow is a machine learning framework.

Affected versions of this package are vulnerable to Arbitrary File Write via Archive Extraction (Zip Slip) via a crafted archive when tf.keras.utils.get_file is used with extract=True.

NOTE: This CVE is disputed as the vendor's position is that tf.keras.utils.get_file is not intended for untrusted archives. However, we feel this advisory is relevant as at the time of publication, there is no known security notice or documentation warning users of this behavior.

UPDATE: With the addition of a clear warning to the API documentation on Feb 23, 2023, this issue is considered fixed.

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

CVSS Scores

version 3.1