Privilege escalation in Linux kernel

1) Use-after-free error

EUVDB-ID: #VU2513

Risk: Medium

CVSSv3.1: 8.2 [CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H/E:F/RL:O/RC:C]

CVE-ID: CVE-2016-0728

CWE-ID: CWE-119 - Memory corruption

Exploit availability: Yes

Description

The vulnerability allows a local attacker to gain elevated privileges on the target system.

The weakness exists due to use-after-free error in the join_session_keyring() function in security/keys/process_keys.c when handling keyring object reference counting by Linux kernel's key management subsystem. A local attacker can overflow the usage field via a specially crafted object and execute arbitrary code with root privileges.

Successful exploitation of the vulnerability may result in arbitrary code execution on the vulnerable system.

Note: the vulnerability was being actively exploited.

Mitigation

Update to version 4.4.1.

Vulnerable software versions

Linux kernel: 3.8 - 4.4.1

External links

http://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=3a50597de8635cd05133bd12c9...
http://perception-point.io/2016/01/14/analysis-and-exploitation-of-a-linux-kernel-vulnerability-cve-...

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. However, a fully functional exploit for this vulnerability is available.