CVE-2021-42255: Vulnerability-Disclosures/MNDT-2022-0022.md at master · mandiant/Vulnerability-Disclosures

MNDT-2022-0022****Description

AppGuard Agent for Windows contains a local privilege escalation vulnerability prior to version 6.7.100.1.

Impact

High - Exploiting the vulnerability will give a local unprivileged attacker SYSTEM level privileges.

Exploitability

Medium - Any authenticated local user can exploit the vulnerability and an exploit is trivial to produce.

CVE Reference

CVE-2021-42255

Common Weakness Enumeration

CWE-379: Creation of Temporary File in Directory with Insecure Permissions

Common Vulnerability Scoring System

Base Score: 7.8 - Vector: AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Technical Details

The installation of the agent uses the Windows Installer framework and an MSI file is cached in c:\windows\installer. An unprivileged user can trigger a repair operation, either by using the Windows Installer API or by running "msiexec.exe /fa c:\windows\installer\[XXXXX].msi".

Running a repair operation will trigger a number of file operations in the %TEMP% folder of the user triggering the repair. Some of these operations will be performed from a SYSTEM context (started via the Windows Installer service), including the execution of temporary files.

Resolution

The issue was fixed in version 6.7.100.1. Update to this version to address the vulnerability.

Discovery Credits

• Ronnie Salomonsen, Mandiant

Disclosure Timeline

• 13-Oct-2021 - Issue reported to AppGuard.
• 08-Nov-2021 - Issue confirmed by AppGuard and a fix scheduled for March 1, 2022
• 01-Mar-2022 - Issue fixed

References

• Mitre CVE-2021-42255