CVE-2019-0841: AppXSvc Hard Link Privilege Escalation

2019-04-0900:00:00

attackerkb.com

CVSS2

7.2

Attack Vector

LOCAL

Attack Complexity

LOW

Authentication

NONE

Confidentiality Impact

COMPLETE

Integrity Impact

COMPLETE

Availability Impact

COMPLETE

AV:L/AC:L/Au:N/C:C/I:C/A:C

CVSS3

7.8

Attack Vector

LOCAL

Attack Complexity

LOW

Privileges Required

LOW

User Interaction

NONE

Scope

UNCHANGED

Confidentiality Impact

HIGH

Integrity Impact

HIGH

Availability Impact

HIGH

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

AI Score

7.3

Confidence

High

EPSS

0.866

Percentile

98.6%

JSON

An elevation of privilege vulnerability exists when Windows AppX Deployment Service (AppXSVC) improperly handles hard links, aka ‘Windows Elevation of Privilege Vulnerability’. This CVE ID is unique from CVE-2019-0730, CVE-2019-0731, CVE-2019-0796, CVE-2019-0805, CVE-2019-0836.

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