Arbitrary File Write via Archive Extraction (Zip Slip) Affecting github.com/rclone/rclone/cmd/rcd Open this link in a new tab package, versions <1.49.4
Attack Complexity
High
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snyk-id
SNYK-GOLANG-GITHUBCOMRCLONERCLONECMDRCD-472939
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published
11 Oct 2019
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disclosed
11 Sep 2019
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credit
Semmle Security Research
Introduced: 11 Sep 2019
CWE-22 Open this link in a new tabHow to fix?
Upgrade github.com/rclone/rclone/cmd/rcd
to version 1.49.4 or higher.
Overview
github.com/rclone/rclone/cmd/rcd is a package part of rclone - "rsync for cloud storage".
Affected versions of this package are vulnerable to Arbitrary File Write via Archive Extraction (Zip Slip). Files within a zip file can break out of the target directory when being 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