vulnerability announce CVE-2010-0788 ncpfs: privilege elevation via ncpmount and ncpumount
Synthesis of the vulnerability

When the ncpmount and ncpumount tools are installed suid root, a local attacker can use a symbolic link, in order to elevate his privileges, to obtain information or to create a denial of service.

Severity: 2/4. Consequences: administrator access/rights, privileged access/rights, user access/rights, data reading, denial of service of service, denial of service of client. Provenance: user shell. Means of attack: 1 attack. Ability of attacker: technician (2/4). Confidence: confirmed by the editor (5/5). Diffusion of the vulnerable configuration: high (3/3). Creation date: 29/01/2010.

Impacted products

• Fedora versions
• Mandriva Corporate versions
• Mandriva Enterprise Server versions
• Mandriva Linux versions
• Mandriva Multi Network Firewall versions
• Novell Linux Desktop versions
• Novell Open Enterprise Server versions
• OpenSUSE versions
• SUSE Linux Enterprise Server versions
• Unix - plateform

Description of the vulnerability

The ncpmount and ncpumount utilities are used to mount a remote NCP (NetWare Core Protocol) share in a local directory. These tools are frequently installed suid root. However, the ncpmount tool does not atomically check the mount directory. A local attacker can therefore:  - call ncpmount to mount a remote share on /home/user/mydir  - during its execution, replace /home/user/mydir by a symbolic link to /privatedirectory  - wait for ncpmount to mount the share on /privatedirectory So, by modifying/reading the content of the share on the remote server, the local attacker can modify/read to content of /privatedirectory. Moreover, the ncpumount tool does not atomically check the directory to be unmounted. A local attacker can therefore:  - call "ncpumount /home/user/mydir"  - during its execution, replace /home/user/mydir by a symbolic link to /privatedirectory  - wait for ncpumount to unmount /privatedirectory A local attacker can thus unmount a mount point belonging to another user. When the ncpmount and ncpumount tools are installed suid root, a local attacker can therefore use a symbolic link, in order to elevate his privileges, to obtain information or to create a denial of service.

Characteristics

Title: ncpfs: privilege elevation via ncpmount and ncpumount Identifiers: 532940, CVE-2010-0788, FEDORA-2010-1145, FEDORA-2010-1168, MDVSA-2010:046, REJ-2009-3297, SUSE-SR:2010:004, VIGILANCE-VUL-9392. Url: https://vigilance.fr/tree/1/9392

Information sources

Publications and announces Source example: CVE-2009-3297 samba, fuse, ncpfs: Race condition by mount (mount.cifs, ncpmount) / umount (fusermount, ncpumount) operations

Solutions for this vulnerability

Patch or workaround

Supplements

Attack Exploit 0day or proof of concept