Type Confusion Affecting krata-tokio-tar package, versions *

krata-tokio-tar is a Rust implementation of an async TAR file reader and writer. This library does not currently handle compression, but it is abstract over all I/O readers and writers. Additionally, great lengths are taken to ensure that the entire contents are never required to be entirely resident in memory all at once.

Affected versions of this package are vulnerable to Type Confusion via inconsistent PAX/ustar header handling. An attacker can overwrite arbitrary files on the system by supplying a crafted tar archive containing PAX-extended headers containing size overrides.

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

• async-tar Patch
• GitHub Commit
• krata-tokio-tar Patch
• Vulnerability Disclosure