#VU85867 UNIX Hard Link in NoMachine - CVE-2023-39107

Vulnerability identifier: #VU85867

Vulnerability risk: Low

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

CVE-ID: CVE-2023-39107

CWE-ID: CWE-62

Exploitation vector: Local

Exploit availability: No

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

Vendor: NoMachine

Description

The vulnerability allows a local user to overwrite arbitrary files on the system.

The vulnerability exists due to insecure permissions for the log directory in /Library/Application Support/NoMachine/var on macOS. A local user can create a hard link to a critical file on the system and overwrite it with root privileges, resulting in a denial of service attack.

Mitigation
Install updates from vendor's website.

Vulnerable software versions

NoMachine: before 8.8.1

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External links
https://kb.nomachine.com/SU07U00247
https://kb.nomachine.com/TR07U10948
https://www.ns-echo.com/posts/nomachine_afo.html

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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.