Arbitrary File Write via Archive Extraction (Zip Slip)

Affecting minitar gem, versions <0.6

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Overview

minitar is a pure-Ruby library that provides the ability to deal with POSIX tar(1) archive 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

Related to rubyzip and archive-tar-minitar.

Remediation

Upgrade minitar to version 0.6 or higher.

References

CVSS Score

7.5
high severity
  • Attack Vector
    Network
  • Attack Complexity
    Low
  • Privileges Required
    None
  • User Interaction
    None
  • Scope
    Unchanged
  • Confidentiality
    None
  • Integrity
    High
  • Availability
    None
CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
Credit
ecneladis
CVE
CVE-2016-10173
CWE
CWE-29
Snyk ID
SNYK-RUBY-MINITAR-20335
Disclosed
21 Aug, 2016
Published
06 Mar, 2017