Affected Software: avast! Antivirus 4.x

A security issue has been reported in avast! Antivirus, which can be exploited by malicious, local users to bypass certain security restrictions or gain escalated privileges.

The security issue is caused due to insecure default file permissions being set on the installed files and folders. This allows any non-privileged users on the system to remove the files or replace them with malicious binaries.

Successful exploitation reportedly requires that the TEMP folder is on the same drive as the avast! installation folder.

The security issue has been confirmed in avast! Professional Edition version 4.6.763 with database 612-0 and also reported in the Home Edition. Other versions may also be affected.

Solution: Restrict access to affected systems.