Arbitrary File Write via Archive Extraction (Zip Slip)

Affecting unzipper package, versions <0.8.13

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Overview

unzipper is a library for the Uzip cross-platform streaming AP.I

Affected versions of this package are vulnerable to Arbitrary File Write via Archive Extraction (Zip Slip). ## Overview unzipper is an Unzip cross-platform streaming API.

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 unzipper to version 0.8.13 or higher.

Details

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 unzipper to version 0.8.13 or higher.

References

CVSS Score

9.4
high severity
  • Attack Vector
    Network
  • Attack Complexity
    Low
  • Privileges Required
    None
  • User Interaction
    None
  • Scope
    Unchanged
  • Confidentiality
    Low
  • Integrity
    High
  • Availability
    High
CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:H/A:H/E:H/RL:O/RC:C
Credit
Snyk Security Research Team
CVE
CVE-2018-1002203
CWE
CWE-29
Snyk ID
npm:unzipper:20180415
Disclosed
14 Apr, 2018
Published
31 May, 2018