Arbitrary File Write via Archive Extraction (Zip Slip)

Affecting decompress package, versions <4.2.1

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Overview

decompress is a package that can be used for extracting archives.

Affected versions of this package are vulnerable to Arbitrary File Write via Archive Extraction (Zip Slip). It is possible to bypass the security measures provided by decompress and conduct ZIP path traversal through symlinks.

PoC

const decompress = require('decompress');

decompress('slip.tar.gz', 'dist').then(files => {
    console.log('done!');
});

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 decompress to version 4.2.1 or higher.

References

CVSS Score

6.3
medium severity
  • Attack Vector
    Network
  • Attack Complexity
    High
  • Privileges Required
    Low
  • User Interaction
    None
  • Scope
    Changed
  • Confidentiality
    High
  • Integrity
    None
  • Availability
    None
CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:H/I:N/A:N/E:P/RL:U/RC:C
Credit
Oscar Arnflo
CVE
CVE-2020-12265
CWE
CWE-29
Snyk ID
SNYK-JS-DECOMPRESS-557358
Disclosed
15 Oct, 2019
Published
27 Feb, 2020