Arbitrary File Write via Archive Extraction (Zip Slip) Affecting mobsf package, versions [0,]

mobsf is a Mobile Security Framework (MobSF) is an automated, all-in-one mobile application (Android/iOS/Windows) pen-testing, malware analysis and security assessment framework capable of performing static and dynamic analysis.

Affected versions of this package are vulnerable to Arbitrary File Write via Archive Extraction (Zip Slip) via the ar_extract function in the shared_func.py component during the extraction of .a extension files. This vulnerability derives due to improper user input sanitization, allowing an attacker to bypass existing protections using sequences like ....//....//....//.

Exploiting this vulnerability allows an attacker to write arbitrary files to any location on the server by manipulating the file path in the archive.

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

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