Arbitrary File Write via Archive Extraction (Zip Slip)

Affecting github.com/openshift/source-to-image/pkg/tar package, versions <1.1.10

medium severity

Overview

github.com/openshift/source-to-image/pkg/tar is a toolkit and workflow for building reproducible Docker images from source code.

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 github.com/openshift/source-to-image/pkg/tar to version 1.1.10 or higher.

References

Do your applications use this vulnerable package?

Credit
Michael Hanselmann
CVE
CVE-2018-1103
CWE
CWE-22
Snyk ID
SNYK-GOLANG-GITHUBCOMOPENSHIFTSOURCETOIMAGEPKGTAR-50077
Disclosed
28 Mar, 2018
Published
17 Jun, 2018