CVE-2019-19191

Shibboleth Service Provider (SP) 3.x before 3.1.0 shipped a spec file that calls chown on files in a directory controlled by the service user (the shibd account) after installation. This allows the user to escalate to root by pointing symlinks to files such as /etc/shadow.

Weakness

The product attempts to access a file based on the filename, but it does not properly prevent that filename from identifying a link or shortcut that resolves to an unintended resource.

Affected Software

Potential Mitigations

• Follow the principle of least privilege when assigning access rights to entities in a software system.
• Denying access to a file can prevent an attacker from replacing that file with a link to a sensitive file. Ensure good compartmentalization in the system to provide protected areas that can be trusted.

Related Attack Patterns

• https://cwe.mitre.org/data/definitions/132.html
• https://cwe.mitre.org/data/definitions/17.html
• https://cwe.mitre.org/data/definitions/35.html
• https://cwe.mitre.org/data/definitions/76.html

References

• http://lists.opensuse.org/opensuse-security-announce/2020-01/msg00017.html
• https://bugzilla.suse.com/show_bug.cgi?id=1157471
• https://issues.shibboleth.net/jira/browse/SSPCPP-874