Arbitrary File Write via Archive Extraction (Zip Slip) Affecting bower package, versions <1.8.8


0.0
high

Snyk CVSS

    Attack Complexity Low
    User Interaction Required
    Confidentiality High
    Integrity High
    Availability High

    Threat Intelligence

    EPSS 0.25% (65th percentile)
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NVD
7.5 high

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  • Snyk ID SNYK-JS-BOWER-73627
  • published 25 Jan 2019
  • disclosed 24 Jan 2019
  • credit skyn3t

How to fix?

Upgrade bower to version 1.8.8 or higher.

Overview

bower offers a generic, unopinionated solution to the problem of front-end package management.

Affected versions of this package are vulnerable to Arbitrary File Write via Archive Extraction (Zip Slip). Attackers can write arbitrary files when a malicious archive is extracted.

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