MNDT-2021-0010
Barracuda Network Access Client (NAC/VPN) for Windows contains a local privilege escalation vulnerability prior to version 5.2.2.
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-2021-42711
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 5.2.2. Update to this version to address the vulnerability.
Discovery Credits
- Ronnie Salomonsen, Mandiant
Disclosure Timeline
- 14-Oct-2021 - Issue reported to Barracuda
- 18-Oct-2021 - Issue confirmed by Barracuda and a fix scheduled for November 24
- 24-Nov-2021 - Patched version released by Barracuda