Advisory Details

This vulnerability allows local attackers to escalate privileges on affected installations of Avast Free Antivirus. An attacker must first obtain the ability to execute low-privileged code on the target system in order to exploit this vulnerability.

The specific flaw exists within the Avast Service. By creating a symbolic link, an attacker can abuse the service to delete a folder. An attacker can leverage this vulnerability to escalate privileges and execute arbitrary code in the context of SYSTEM.

1/03/24 – ZDI reported the vulnerability to Avast’s Security Reports team.
02/12/24 – ZDI asked for updates.
02/23/24 – ZDI asked for updates.
03/15/24 – ZDI informed the vendor that since we’ve not received a response
that we will publish the case as a zero-day advisory on 03/27/24.
04/25/24 – A Gen Digital team member communicated that all the security issues should be submitted via a third-party Vulnerability Disclosure program
05/16/24 – ZDI resubmitted the vulnerability to the third-party Vulnerability Disclosure program
06/19/24 – ZDI asked for updates
07/26/24 – ZDI informed the vendor that since we’ve not received a response that we will publish the case as a zero-day advisory on 07/29/24

-- Mitigation: Given the nature of the vulnerability, the only salient mitigation strategy is to restrict interaction with the application.

• 2024-05-16 - Vulnerability reported to vendor
• 2024-07-29 - Coordinated public release of advisory
• 2024-08-15 - Advisory Updated