Rhc: rhc: local privilege escalation via symlink following in rhc-canonical-facts.service

Overview

A flaw was found in the rhc-canonical-facts.service systemd unit shipped with rhc. The service runs as root and operates on a file inside a directory owned by an unprivileged system user without verifying that the file is not a symbolic link. A local attacker who has already compromised the privileged yggdrasil system service account can exploit this to gain ownership of arbitrary files, leading to privilege escalation to root.

Affected

• rhc (all versions)
• rhc
• rhc
• rhc

Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.

Workarounds

Disable the rhc-canonical-facts timer to prevent automatic triggering of the vulnerable service:

systemctl stop rhc-canonical-facts.timer
systemctl disable rhc-canonical-facts.timer

Note that this will prevent rhc from updating canonical facts automatically. The rhc connect command will still trigger the service manually.