Arbitrary File Write via Archive Extraction (Zip Slip) Affecting github.com/mholt/archiver/cmd/archiver package, versions <2.1.0


Severity

Recommended
0.0
medium
0
10

CVSS assessment made by Snyk's Security Team

    Threat Intelligence

    EPSS
    0.09% (37th percentile)

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  • Snyk ID SNYK-GOLANG-GITHUBCOMMHOLTARCHIVERCMDARCHIVER-50071
  • published 31 May 2018
  • disclosed 13 Apr 2018
  • credit Snyk Security research Team

How to fix?

Upgrade github.com/mholt/archiver/cmd/archiver to version e4ef56d48eb029648b0e895bb0b6a393ef0829c3 or higher.

Overview

github.com/mholt/archiver/cmd/archiver makes it trivially easy to make and extract common archive formats such as .zip, and .tar.gz. Simply name the input and output file(s).

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

CVSS Scores

version 3.1
Expand this section

Snyk

5.5 medium
  • Attack Vector (AV)
    Local
  • Attack Complexity (AC)
    Low
  • Privileges Required (PR)
    None
  • User Interaction (UI)
    Required
  • Scope (S)
    Unchanged
  • Confidentiality (C)
    None
  • Integrity (I)
    High
  • Availability (A)
    None