Arbitrary File Write via Archive Extraction (Zip Slip) Affecting chumper/zipper package, versions <1.0.3

chumper/zipper is a little neat helper for the ZipArchive methods with handy functions.

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

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

$zipper->make('/archives/zip-slip.zip')->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

• Chumper/Zipper GitHub Commit
• DariusIII/Zipper GitHub Commit
• madnest/madzipper GitHub Commit