CVE-2019-1477 in Windows
Summary
by MITRE
An elevation of privilege vulnerability exists when the Windows Printer Service improperly validates file paths while loading printer drivers, aka 'Windows Printer Service Elevation of Privilege Vulnerability'.
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Analysis
by VulDB Data Team • 03/09/2024
The vulnerability described in CVE-2019-1477 represents a critical elevation of privilege flaw within the Windows operating system's printer service component. This issue specifically manifests when the Windows Printer Service fails to properly validate file paths during the process of loading printer drivers, creating a pathway for malicious actors to escalate their privileges from standard user level to system level access. The vulnerability affects multiple Windows versions including Windows 10, Windows Server 2016, and Windows Server 2019, making it a widespread concern across enterprise environments. The flaw resides in the service's handling of printer driver installations and updates, where insufficient input validation allows for path traversal attacks that can be exploited to load malicious code with elevated privileges.
The technical implementation of this vulnerability stems from improper validation of file paths within the Windows Printer Service execution flow. When a user attempts to install or update a printer driver, the service processes the specified file paths without adequate sanitization or verification of the intended destination. This weakness enables attackers to craft malicious printer driver packages that contain specially crafted file paths designed to exploit the validation gap. The vulnerability can be triggered through various attack vectors including malicious printer driver installations, remote code execution via network printer connections, or local exploitation through user interaction with malicious print jobs. According to CWE classification, this vulnerability maps to CWE-22 Path Traversal, which specifically addresses improper validation of file paths and directory access controls. The ATT&CK framework categorizes this as privilege escalation through service exploitation, specifically targeting Windows Printer Service as an attack surface that can be leveraged for system-level access.
The operational impact of CVE-2019-1477 is severe and far-reaching within enterprise networks where Windows systems are prevalent. Successful exploitation allows attackers to gain system-level privileges, enabling them to install malware, modify system files, access sensitive data, and establish persistent backdoors within the compromised environment. The vulnerability can be exploited remotely, making it particularly dangerous for organizations with networked printers or those that allow automatic printer driver installations. In many enterprise scenarios, the Windows Printer Service runs with elevated privileges, creating a perfect storm where a single compromised printer driver installation can result in complete system compromise. Organizations may experience unauthorized access to confidential information, system corruption, and potential lateral movement within the network through the elevated privileges gained. The vulnerability also poses significant risk to organizations with print servers or managed print environments where multiple users interact with shared printer resources.
Mitigation strategies for CVE-2019-1477 should focus on both immediate patching and operational security measures. Microsoft released security updates in the August 2019 Patch Tuesday release that address this vulnerability by implementing proper file path validation within the Windows Printer Service. Organizations must prioritize applying these security updates across all affected Windows systems to eliminate the exploitability of this vulnerability. Additionally, implementing network segmentation and restricting printer service access can help limit the potential impact of exploitation attempts. Security controls should include disabling unnecessary printer services, implementing strict printer driver installation policies, and monitoring for unusual printer service activities. The principle of least privilege should be enforced by ensuring that printer service accounts operate with minimal required permissions and that printer driver installations are restricted to authorized administrators only. Network-based mitigations include blocking unnecessary printer ports and implementing firewall rules that restrict communication with potentially compromised printer endpoints. Organizations should also consider implementing endpoint detection and response solutions that can identify anomalous printer service behaviors or attempts to load unauthorized printer drivers, providing visibility into potential exploitation attempts.