#VU14514 Privilege escalation in Ubuntu - CVE-2018-6557

Vulnerability identifier: #VU14514

Vulnerability risk: Low

CVSSv4.0: 5.9 [CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:U/U:Clear]

CVE-ID: CVE-2018-6557

CWE-ID: CWE-264

Exploitation vector: Local

Exploit availability: No

Vulnerable software:
Ubuntu
Operating systems & Components / Operating system

Vendor: Canonical Ltd.

Description

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

The vulnerability exists in the MOTD update script due to improper processing of temporary files. A local attacker can supply specially crafted symbolic links (symlinks) from a temporary file to a critical file on the system to overwrite files with administrator privileges.

Mitigation
Install update from vendor's website.

Vulnerable software versions

Ubuntu: 18.04

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External links
https://usn.ubuntu.com/3748-1/

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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.