CVE-2019-1130
Microsoft Windows AppX Deployment Service Privilege Escalation Vulnerability
Description
CVE-2019-1130 is a privilege escalation vulnerability in the Windows AppX Deployment Service (AppXSVC) caused by improper handling of hard links. This flaw allows a local attacker to escalate their privileges by exploiting the way AppXSVC processes hard links during application deployment operations. CISA has confirmed active exploitation and included CVE-2019-1130 in the Known Exploited Vulnerabilities (KEV) catalog with a known ransomware association. With an EPSS percentile of 83.2%, this vulnerability represents a significant threat, particularly to organizations targeted by ransomware operators.
KEV Information
CVSS Score
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:HOpen in CalculatorAffected Products
| Vendor | Product | Version |
|---|---|---|
| microsoft | windows 10 1507 | - |
| microsoft | windows 10 1607 | - |
| microsoft | windows 10 1703 | - |
| microsoft | windows 10 1709 | - |
| microsoft | windows 10 1803 | - |
| microsoft | windows 10 1809 | - |
| microsoft | windows 10 1903 | - |
| microsoft | windows 8.1 | - |
| microsoft | windows rt 8.1 | - |
| microsoft | windows server 1803 | - |
| microsoft | windows server 1903 | - |
| microsoft | windows server 2012 | -; r2 |
| microsoft | windows server 2016 | - |
| microsoft | windows server 2019 | - |
Multiple CVSS Assessments
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
References
- https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2019-1130(Patch, Vendor Advisory)
- https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2019-1130(US Government Resource)
Weakness Type
CWE-269: Improper Privilege Management
CWE-269 describes weaknesses where a product does not properly assign, modify, track, or check privileges. In CVE-2019-1130, the Windows AppX Deployment Service improperly handles hard links during privileged file operations, allowing a local attacker to redirect these operations to access or modify system-protected files, effectively escalating their privilege level.
Learn more: CWE-269 — Improper Privilege Management
Impact Analysis
CVE-2019-1130 is a local privilege escalation vulnerability in the Windows AppX Deployment Service (AppXSVC) that allows an attacker with standard user access to gain elevated privileges through hard link manipulation. When exploited, the attacker can redirect privileged file operations performed by AppXSVC to arbitrary file system locations, gaining read or write access to system-protected files and directories. This can lead to full system compromise, as the attacker can modify security configurations, replace system binaries, or access credential stores. The confirmed ransomware association in the CISA KEV catalog significantly amplifies the threat — ransomware operators leverage this privilege escalation to gain the elevated access needed to disable antivirus software, encrypt system volumes, and deploy ransomware payloads across the network. The EPSS percentile of 83.2% indicates high exploitation probability, and the combination of confirmed active exploitation with ransomware usage makes this a critical remediation priority.
Exploit Maturity
CISA has confirmed active exploitation of CVE-2019-1130 by including it in the Known Exploited Vulnerabilities catalog with a remediation deadline of June 13, 2022. The KEV catalog flags this vulnerability with a known ransomware association, confirming that ransomware operators actively use this privilege escalation in their attack chains. The EPSS percentile of 83.2% reflects substantial real-world exploitation activity. Hard link-based privilege escalation vulnerabilities in Windows services are well-understood attack techniques, and the public availability of research into AppXSVC file operation abuse lowers the barrier for exploitation. Ransomware groups typically chain this type of vulnerability with initial access exploits to transition from a standard user context to SYSTEM-level access, enabling maximum impact during the ransomware deployment phase.
Remediation
- Apply the security updates provided by Microsoft for the Windows AppX Deployment Service as specified in the associated security advisory. CISA mandates remediation by June 13, 2022.
- Given the ransomware association, prioritize patching on file servers, domain controllers, backup systems, and other critical infrastructure where privilege escalation would enable devastating ransomware deployment.
- Monitor AppXSVC for suspicious hard link creation and file operation redirection attempts that may indicate exploitation, particularly hard links pointing from AppX deployment directories to system-critical locations.
- Deploy endpoint detection and response (EDR) solutions with detection rules for privileged file operation abuse and hard link/junction-based privilege escalation techniques.
- Implement robust backup and recovery procedures with offline, air-gapped backups to ensure resilience against ransomware attacks leveraging CVE-2019-1130 for privilege escalation.
Technical Details
CVE-2019-1130 exploits a flaw in the Windows AppX Deployment Service (AppXSVC) related to its handling of hard links during application package deployment operations. AppXSVC runs as a SYSTEM-level service and performs various file system operations with elevated privileges during the installation, update, and removal of AppX/MSIX application packages. The vulnerability arises because AppXSVC does not properly validate or restrict hard links encountered during these file operations. A local attacker can create hard links in directories used by the AppX deployment process that point to system-protected files elsewhere on the disk. When AppXSVC subsequently performs privileged operations on what it believes are legitimate deployment files, the hard links redirect these operations to the attacker-specified target files. This technique effectively uses AppXSVC as a confused deputy — the service's own elevated privileges are leveraged to perform file operations that the attacker's standard user account would not normally be authorized to execute, resulting in privilege escalation from standard user to SYSTEM level.
Frequently Asked Questions
Is CVE-2019-1130 being actively exploited?
Yes, CVE-2019-1130 is being actively exploited with confirmed ransomware association. CISA has included it in the KEV catalog, and its EPSS percentile of 83.2% confirms significant exploitation activity. Ransomware operators actively use this vulnerability in their attack chains.
What products are affected by CVE-2019-1130?
CVE-2019-1130 affects the Windows AppX Deployment Service (AppXSVC) in Microsoft Windows. Multiple Windows versions are impacted. Administrators should consult Microsoft's security advisory for the complete list of affected operating system versions.
How do I fix CVE-2019-1130?
Apply Microsoft's security updates for the affected Windows versions. Prioritize patching on critical infrastructure and backup systems. Deploy EDR solutions to detect hard link abuse and implement offline backup procedures for ransomware resilience.
How severe is CVE-2019-1130?
CVE-2019-1130 is a serious privilege escalation vulnerability with an EPSS percentile of 83.2% and confirmed ransomware association. The combination of active exploitation and ransomware usage makes this a high-priority remediation target. Successful exploitation enables SYSTEM-level access through hard link manipulation.
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