CVE-2019-0841: AppXSvc Hard Link Privilege Escalation

An elevation of privilege vulnerability exists when Windows AppX Deployment Service (AppXSVC) improperly handles hard links. An attacker who successfully exploited this vulnerability could run processes in an elevated context. An attacker could then install programs; view, change or delete data.

Recent assessments:

space-r7 at July 12, 2019 2:39pm UTC reported:

This vulnerability allows for taking over SYSTEM-owned files. Getting an elevated shell takes more effort, either by exposing the DiagHub service, which will willingly load a file from System32 with SYSTEM privileges or by combing the target for a service that loads a dll as SYSTEM. Exploitability is variable due to those reasons, but ultimately this is a useful vulnerability. Effort to execute this exploit is rated higher due to shell access being a prerequisite.

There is even a bypass for this vulnerability’s patch: CVE-2019-1064.

Assessed Attacker Value: 4
Assessed Attacker Value: 4Assessed Attacker Value: 2