Arbitrary File Write via Archive Extraction (Zip Slip)

Affecting github.com/mholt/archiver/cmd/archiver package

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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

Remediation

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

References

CVSS Score

5.5
medium severity
  • Attack Vector
    Local
  • Attack Complexity
    Low
  • Privileges Required
    None
  • User Interaction
    Required
  • Scope
    Unchanged
  • Confidentiality
    None
  • Integrity
    High
  • Availability
    None
CVSS:3.0/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:N
Credit
Snyk Security research Team
CVE
CVE-2018-1002207
CWE
CWE-29
Snyk ID
SNYK-GOLANG-GITHUBCOMMHOLTARCHIVERCMDARCHIVER-50071
Disclosed
13 Apr, 2018
Published
31 May, 2018