Arbitrary File Write via Archive Extraction (Zip Slip)

Affecting rubyzip gem, versions <1.2.2

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Overview

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

NOTE This vulnerability is due to a partial fix in CVE-2017-5946

Remediation

Upgrade rubyzip to version 1.2.2 or higher.

References

CVSS Score

7.3
high severity
  • Attack Vector
    Network
  • Attack Complexity
    Low
  • Privileges Required
    None
  • User Interaction
    None
  • Scope
    Unchanged
  • Confidentiality
    Low
  • Integrity
    Low
  • Availability
    Low
CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L/E:H
Credit
Unknown
CVE
CVE-2018-1000544
CWE
CWE-22
Snyk ID
SNYK-RUBY-RUBYZIP-22039
Disclosed
13 Jun, 2018
Published
28 Jun, 2018