Werk #16361: Privilege escalation in Windows agent

Component Checks & agents
Title Privilege escalation in Windows agent
Date Feb 26, 2024
Checkmk Edition Checkmk Raw (CRE)
Checkmk Version 2.1.0p40 2.2.0p23 2.3.0b1 2.4.0b1
Level Trivial Change
Class Security Fix
Compatibility Compatible - no manual interaction needed

In order to execute some system commands Checkmk Windows agent writes cmd files to C:\Windows\Temp\ and afterwards executes them. The permissions of the files were set restrictive but existing files were not properly handled. If a cmd file already existed and was write protected the agent was not able to rewrite the file but did not handle this case and executed the file nevertheless.

We thank Michael Baer (SEC Consult Vulnerability Lab) for reporting this issue.

Affected Versions: * 2.2.0 * 2.1.0 * 2.0.0

Indicators of Compromise: The filename of the cmd file needed to be guessed therefore the proof-of-concept creates a lot of files in C\Windows\Temp with the filename cmk_all_\d+_1.cmd. These file-creation events could be monitored.

Vulnerability Management: We have rated the issue with a CVSS Score of 8.8 (High) with the following CVSS vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H. We assigned CVE-2024-0670 to this vulnerability.

Changes: This Werk changes the temp folder and adds a subfolder with more restrictive permissions in which the files are created. Also errors are handled better.

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