Arbitrary File Write via Archive Extraction (Zip Slip) Affecting ansible package, versions [,2.7.17)[2.8.0,2.8.9)[2.9.0,2.9.6)


Severity

Recommended
0.0
medium
0
10

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

Threat Intelligence

Exploit Maturity
Proof of concept
EPSS
0.05% (16th percentile)

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  • Snyk IDSNYK-PYTHON-ANSIBLE-559542
  • published9 Mar 2020
  • disclosed9 Mar 2020
  • creditSam Doran

Introduced: 9 Mar 2020

CVE-2020-1737  (opens in a new tab)
CWE-29  (opens in a new tab)

How to fix?

Upgrade ansible to version 2.7.17, 2.8.9, 2.9.6 or higher.

Overview

ansible is a simple IT automation system.

Affected versions of this package are vulnerable to Arbitrary File Write via Archive Extraction (Zip Slip). A flaw was found when using the Extract-Zip function from the win_unzip module as the extracted file(s) are not checked if they belong to the destination folder. An attacker could take advantage of this flaw by crafting an archive anywhere in the file system, using a path traversal. This issue is fixed in 2.10.

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