Attacker Value
High
(1 user assessed)
Exploitability
Low
(1 user assessed)
User Interaction
None
Privileges Required
Low
Attack Vector
Local
0

CVE-2019-0841: AppXSvc Hard Link Privilege Escalation

Disclosure Date: April 09, 2019 •
CVE-2019-0841 CVSS v3 Base Score: 7.8
Exploited in the Wild
Reported by gwillcox-r7
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Description

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.

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2
Ratings
  • Attacker Value
    High
  • Exploitability
    Low
Technical Analysis

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.

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CVSS V3 Severity and Metrics
Base Score:
7.8 High
Impact Score:
5.9
Exploitability Score:
1.8
Vector:
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Attack Vector (AV):
Local
Attack Complexity (AC):
Low
Privileges Required (PR):
Low
User Interaction (UI):
None
Scope (S):
Unchanged
Confidentiality (C):
High
Integrity (I):
High
Availability (A):
High

General Information

Offensive Application
post
Utility Class
privesc
Ports
Unknown
OS
Windows 10
Vulnerable Versions
Builds prior to 17763
Prerequisites
Unknown
Discovered By
rogue_kdc
PoC Author
rogue_kdc
Metasploit Module
Unknown
Reporter
Shelby Pace

Vendors

  • microsoft

Products

  • windows 10 1703,
  • windows 10 1709,
  • windows 10 1803,
  • windows 10 1809,
  • windows server 2016 1803,
  • windows server 2019 -

Additional Info

Authenticated
Never
Exploitable
Unknown
Reliability
Unknown
Stability
Moderate
Available Mitigations
Unknown
Shelf Life
Unknown
Userbase/Installbase
Large
Patch Effectiveness
Low
Technical Analysis