CVE-2019-11502

snap-confine in snapd before 2.38 incorrectly set the ownership of a snap application to the uid and gid of the first calling user. Consequently, that user had unintended access to a private /tmp directory.

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://www.openwall.com/lists/oss-security/2019/04/25/7
• https://github.com/snapcore/snapd/commit/bdbfeebef03245176ae0dc323392bb0522a339b1
• https://www.openwall.com/lists/oss-security/2019/04/18/4