CVE-2016-6253

mail.local in NetBSD versions 6.0 through 6.0.6, 6.1 through 6.1.5, and 7.0 allows local users to change ownership of or append data to arbitrary files on the target system via a symlink attack on the user mailbox.

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://akat1.pl/?id=2
• http://ftp.netbsd.org/pub/NetBSD/security/advisories/NetBSD-SA2016-006.txt.asc
• http://packetstormsecurity.com/files/138021/NetBSD-mail.local-8-Local-Root.html
• http://www.rapid7.com/db/modules/exploit/unix/local/netbsd_mail_local
• http://www.securityfocus.com/bid/92101
• http://www.securitytracker.com/id/1036429
• https://www.exploit-db.com/exploits/40141/
• https://www.exploit-db.com/exploits/40385/