Privilege escalation in libqb

1) UNIX symbolic link following

EUVDB-ID: #VU19263

Risk: Low

CVSSv4.0: 1.1 [CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:L/VI:L/VA:L/SC:N/SI:N/SA:N/E:U/U:Clear]

CVE-ID: CVE-2019-12779

CWE-ID: CWE-61 - UNIX Symbolic Link (Symlink) Following

Exploit availability: No

Description

The vulnerability allows a local user to escalate privileges on the system.

The vulnerability exists due to a symlink following issue because software uses predictable filenames (under /dev/shm and /tmp) without O_EXCL in libqb before 1.0.5. A local user can create a specially crafted symbolic link to a critical file on the system and overwrite it with privileges of the application.

Successful exploitation of this vulnerability may result in privilege escalation.

Mitigation

Install update from vendor's website.

Vulnerable software versions

libqb: 0.1.0 - 1.0.4

CPE2.3

• cpe:2.3:a:clusterlabs:libqb:0.1.0:*:*:*:*:*:*:*
• cpe:2.3:a:clusterlabs:libqb:0.2.0:*:*:*:*:*:*:*
• cpe:2.3:a:clusterlabs:libqb:0.3.0:*:*:*:*:*:*:*

External links

https://bugzilla.redhat.com/show_bug.cgi?id=1695948
https://github.com/ClusterLabs/libqb/issues/338
https://github.com/ClusterLabs/libqb/releases/tag/v1.0.4
https://github.com/ClusterLabs/libqb/releases/tag/v1.0.5

Q & A

Can this vulnerability be exploited remotely?

No. This vulnerability can be exploited locally. The attacker should have authentication credentials and successfully authenticate on the system.

Is there known malware, which exploits this vulnerability?

No. We are not aware of malware exploiting this vulnerability.