Arbitrary File Write via Archive Extraction (Zip Slip) Affecting dariusiii/zipper package, versions <2.0.2

  • Exploit Maturity

    Proof of concept

  • Attack Complexity


  • Integrity


  • Availability


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  • snyk-id


  • published

    25 Feb 2020

  • disclosed

    25 Feb 2020

  • credit

    Sam Sanoop of Snyk Security Team

Introduced: 25 Feb 2020

CWE-29 Open this link in a new tab
First added by Snyk

How to fix?

Upgrade dariusiii/zipper to version 2.0.2 or higher.


dariusiii/zipper is a Simple Wrapper around the ZipArchive methods with some handy functions. This package is an updated fork of Chumper/Zipper.

Affected versions of this package are vulnerable to Arbitrary File Write via Archive Extraction (Zip Slip). ZIP Path traversal is possible during extraction due to no validation and sanitization of filenames.

PoC by Snyk

require __DIR__ . '/vendor/autoload.php';
$zipper = new \Chumper\Zipper\Zipper;

$zipper->make('/archives/')->extractTo('/uploads'); $zipper->close();


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