Privilege escalation in Windows AppX Deployment Service

1) Input validation error

EUVDB-ID: #VU18167

Risk: Low

CVSSv4.0: 6.8 [CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:A/VC:L/VI:H/VA:H/SC:N/SI:N/SA:N/E:A/U:Clear]

CVE-ID: CVE-2019-0841

CWE-ID: CWE-20 - Improper input validation

Exploit availability: Yes

Description

The vulnerability allows a local user to escalate privileges on the system.

The vulnerability exists due to the way Windows AppX Deployment Service (AppXSVC) handles hard links. A local user can create a malicious application, launch it on the system and run processes in an elevated context.

Mitigation

Install update from vendor's website.

Vulnerable software versions

Windows: 10 1703 10.0.15063.138 - 10 1809 10.0.17763.1

Windows Server: 2019 10.0.17763.1 - 2019 1803

CPE2.3

• cpe:2.3:o:microsoft:windows:10_1703:10.0.15063.138:*:*:*:*:*:*
• cpe:2.3:o:microsoft:windows:10_1709:10.0.16299.19:*:*:*:*:*:*
• cpe:2.3:o:microsoft:windows:10_1803:10.0.17134.48:*:*:*:*:*:*
• cpe:2.3:o:microsoft:windows:10_1809:10.0.17763.1:*:*:*:*:*:*
• cpe:2.3:o:microsoft:windows_server:2019:10.0.17763.1:*:*:*:*:*:*
• cpe:2.3:o:microsoft:windows_server:2019_1709:*:*:*:*:*:*:*
• cpe:2.3:o:microsoft:windows_server:2019_1803:*:*:*:*:*:*:*

External links

https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2019-0841

Q & A

Can this vulnerability be exploited remotely?

No. This vulnerability can be exploited locally. The attacker should have authentication credentials and successfully authenticate on the system.

Is there known malware, which exploits this vulnerability?

Yes. This vulnerability is being exploited in the wild.