Arbitrary File Write via Archive Extraction (Zip Slip) Affecting rubyzip package, versions <1.2.1


0.0
medium

Snyk CVSS

    Exploit Maturity Mature
    Attack Complexity Low
Expand this section
NVD
9.8 critical

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  • Snyk ID SNYK-RUBY-RUBYZIP-20336
  • published 6 Mar 2017
  • disclosed 3 Feb 2017
  • credit ecneladis

How to fix?

Upgrade rubyzip to version 1.2.1 or higher.

Overview

rubyzip is rubyzip is a ruby module for reading and writing zip files.

Affected versions of the package are vulnerable to Arbitrary File Write via Archive Extraction (AKA "Zip Slip").

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