Vulnerability identifier: #VU6846

Vulnerability risk: Low

CVSSv3.1: 5.3 [CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L/E:P/RL:O/RC:C]

CVE-ID: CVE-2017-1000367

CWE-ID: CWE-77

Exploitation vector: Local

Exploit availability: Yes

Vulnerable software:
Sudo
Client/Desktop applications / Software for system administration

Vendor: Sudo

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

The weakness exists due to command validation flaw in the get_process_ttyname() function. A local attacker can issue a specially crafted sudo command, cause the system to recognize the user's tty as an arbitrary file and overwrite arbitrary files. Exploitation of the bug is possible in case a malicious user has sudo privileges, the system contains SELinux and sudo has been built on SELinux support.

Successful exploitation of the vulnerability results in root access to the system.

Mitigation
Update to version 1.8.20p1.

Vulnerable software versions

Sudo: 1.8.6p6 - 1.8.20

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External links
http://www.sudo.ws/alerts/linux_tty.html
http://www.openwall.com/lists/oss-security/2017/05/30/16

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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, proof of concept for this vulnerability is available.