Scan evasion and file deletion via process injection

Incorrect default permissions in Avast Antivirus before 20.4 allow local users to evade scans or delete arbitrary system files. The aswEngSrv.exe sandbox process grants Everyone read-write access through its default DACL, allowing code injection that falsifies scan verdicts and makes the privileged AvastSvc.exe service delete attacker-selected files. A standard Windows user can reach the process; direct privilege escalation requires chaining this flaw with separate sandbox-escape vulnerabilities.