CVE-2008-4977

postfix_groups.pl in Postfix 2.5.2 allows local users to overwrite arbitrary files via a symlink attack on the (1) /tmp/postfix_groups.stdout, (2) /tmp/postfix_groups.stderr, and (3) /tmp/postfix_groups.message temporary files. NOTE: the vendor disputes this vulnerability, stating This is not a real issue … users would have to edit a script under /usr/lib to enable it.

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://bugs.debian.org/496401
• http://dev.gentoo.org/~rbu/security/debiantemp/postfix
• http://www.openwall.com/lists/oss-security/2008/10/30/2
• https://bugs.gentoo.org/show_bug.cgi?id=235770
• https://bugs.gentoo.org/show_bug.cgi?id=235811