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Local DoS attack vectors in seunshare 3.10 (SUSE Security Team Blog)
The SUSE Security Team Blog has a post with an analysis of seunshare, which is used by SELinux to confine untrusted programs. During a review of version 3.10 of the program, the team identified two local Denial-of-Service (DoS) vectors.
Since seunshare is supposed to run on SELinux-enabled systems, it is important to understand what kind of privilege escalation can be achieved when vulnerabilities are exploited in a setuid-root binary like this. Many SELinux-enabled systems, such as Fedora and openSUSE, ship with the "targeted" SELinux policy by default. This policy is focused on confining well-known system services, but assigns an unconfined SELinux context to interactive users by default to achieve a balance between security and usability.
There is currently no domain transition from the unconfined domain to the more restricted seunshare_t defined in the SELinux policy for seunshare. This means the execution of seunshare continues in the unconfined domain. Thus in the context of attacks carried out by interactive users, the impact of the vulnerabilities below will be a root-like privilege escalation despite the system running in SELinux enforced mode.
See the post for the full write-up of the team's discoveries and timeline. The vulnerabilities have been fixed in version 3.11.
