Vulnerability identifier: #VU37376

Vulnerability risk: Low

CVSSv3.1: 6.1 [CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C]

CVE-ID: CVE-2018-5731

CWE-ID: CWE-20

Exploitation vector: Local

Exploit availability: No

Vulnerable software:
heimdal
Server applications / Encryption software

Vendor: Heimdal Software

Description

The vulnerability allows a local authenticated user to execute arbitrary code.

An issue was discovered in Heimdal PRO 2.2.190. As part of the scanning feature, a process called md.hs writes an executable called CS1.tmp to C:windowsTEMP. Afterwards the executable is run. It is possible for an attacker to create the file first, let md.hs overwrite it, and then rewrite the file in the window between md.hs closing the file and executing it. This can be exploited via opportunistic locks and a high priority thread. The vulnerability is triggered when a scan starts. NOTE: any affected Heimdal products are completely unrelated to the Heimdal vendor of a Kerberos 5 product on the h5l.org web site.

Mitigation
Install update from vendor's website.

Vulnerable software versions

heimdal: 2.2.190

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External links
http://improsec.com/blog/heimdal-advisory-2

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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.