A flaw was found in sos clean, a utility within the sos package. This vulnerability allows a local attacker to perform arbitrary file creation or overwrite. By crafting a malicious tar archive, an attacker can exploit a path traversal issue during tar extraction, where symlink and hardlink targets are not properly validated. This enables the attacker to write files to arbitrary locations on the system with the privileges of the sos clean process, which often runs as root.

Upstream issue: https://github.com/sosreport/sos/issues/4460 Proposed Fix: https://github.com/sosreport/sos/pull/4461 Component: sos (sos/cleaner/archives/init.py — extractarchive()) CWE: CWE-22 and CWE-59 Suggested CVSS 3.1: AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H (7.8)

Summary: sos clean extracts a caller-supplied tarball with tarfile.fullytrustedfilter. A dest-containment check exists but only inspects member.name. It does not inspect symlink or hardlink targets. extractall() can therefore write files outside the extract directory as the process UID.

Description: A path traversal vulnerability was found in sos clean in the sos package. The extractarchive() function uses Python's tarfile module with fullytrustedfilter and validates only archive member names against the extraction directory. Symlink and hardlink targets are not validated. A crafted tar archive can therefore contain an out-of-tree symlink followed by a regular file whose apparent path remains within the extraction directory. During extraction, tarfile.extractall() follows the symlink and writes the file to an attacker-controlled location outside the extraction directory. This can result in arbitrary file creation or overwrite with the privileges of the sos clean process, which is commonly run as root.

Reporter / Credit: Sandipan Roy (Red Hat)

sos-collector does not set any permission when creating new files, thus the default umask is used, making all newly created files readable by all local users. Given the delicacy of the data collected by sos-collector, all files created by the tool, including the sos-reports collected from the cluster machines, should be accessible only the to current user. A local attacker can use this flaw to read sensitive information collected from other machines when a legit user runs sos-collector.

Upstream patch: https://github.com/sosreport/sos-collector/commit/72058f9253e7ed8c7243e2ff76a16d97b03d65ed