Microsoft Windows AppX Deployment Service (AppXSVC) Privilege Escalation Vulnerability

[ Why it matters ]Priority signals

• Exploited in the wild: on CISA's Known Exploited Vulnerabilities list since 2022-03-15
• Known to be used in ransomware campaigns

[ Description ]Official description

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. To exploit this vulnerability, an attacker would first have to log on to the system. An attacker could then run a specially crafted application that could exploit the vulnerability and take control of an affected system. The security update addresses the vulnerability by correcting how Windows AppX Deployment Service handles hard links.

CISA: A privilege escalation vulnerability exists when Windows AppXSVC improperly handles hard links. An attacker who successfully exploited this vulnerability could run processes in an elevated context.

[ Fixes ]Fixes and patches

CISA required action (US federal deadline 5 Apr 2022): Apply updates per vendor instructions.

• Patch on msrc.microsoft.comVendor patch or bulletin · NVD · Reference tagged 'Patch' by NVD
• Patch on portal.msrc.microsoft.comVendor patch or bulletin · NVD · Reference tagged 'Patch' by NVD

[ References ]References

• msrc.microsoft.com/update-guide/vulnerability/CVE-2019-1064PatchVendor Advisory
• portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2019-1064PatchVendor Advisory
• www.cisa.gov/known-exploited-vulnerabilities-catalogUS Government Resource