CVE-2019-0787 in Windows
Summary
by MITRE
A remote code execution vulnerability exists in the Windows Remote Desktop Client when a user connects to a malicious server, aka 'Remote Desktop Client Remote Code Execution Vulnerability'. This CVE ID is unique from CVE-2019-0788, CVE-2019-1290, CVE-2019-1291.
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Analysis
by VulDB Data Team • 08/19/2020
The vulnerability described in CVE-2019-0787 represents a critical remote code execution flaw within the Windows Remote Desktop Client component that has significant implications for enterprise security infrastructure. This vulnerability specifically affects the RDP client functionality when establishing connections to potentially compromised servers, creating a dangerous attack surface that adversaries can exploit to gain unauthorized system access. The flaw exists in the client-side processing of RDP connections, where malicious servers can craft specially crafted responses that trigger unexpected behavior in the client application. This vulnerability is particularly concerning because it operates at the network level during connection establishment, allowing attackers to execute arbitrary code on victim systems without requiring local access or elevated privileges.
The technical root cause of this vulnerability stems from inadequate input validation and memory handling within the Windows Remote Desktop Client's connection processing pipeline. When the client attempts to establish a connection to a remote server, it processes various RDP protocol messages and data structures that may contain malicious payloads. The vulnerability manifests when the client fails to properly validate or sanitize incoming data from the server, leading to potential buffer overflows or memory corruption scenarios. This type of flaw aligns with CWE-121, which describes heap-based buffer overflow conditions, and CWE-125, which covers out-of-bounds read errors that can lead to code execution. The vulnerability's exploitation typically involves crafting specific RDP server responses that cause the client application to execute unintended code paths, potentially allowing attackers to inject and run malicious code within the context of the RDP client process.
The operational impact of CVE-2019-0787 extends far beyond individual system compromise, as it enables attackers to establish persistent access to enterprise networks through legitimate RDP connections. Organizations that rely heavily on remote desktop services for business operations face severe risks when this vulnerability remains unpatched, as it can serve as an initial access vector for broader network infiltration. Attackers can leverage this vulnerability to move laterally within networks, escalate privileges, and potentially gain access to sensitive data repositories. The vulnerability's remote nature means that exploitation can occur from anywhere on the internet, making it particularly dangerous for organizations with exposed RDP endpoints. According to ATT&CK framework, this vulnerability maps to T1071.004 for application layer protocol usage and T1059 for command and scripting interpreter, as attackers can establish remote command execution capabilities and leverage the compromised client for further reconnaissance and attack progression.
Mitigation strategies for CVE-2019-0787 should encompass both immediate defensive measures and long-term architectural improvements. Microsoft released a security patch through Windows Update that addresses the vulnerability by implementing proper input validation and memory handling within the RDP client component. Organizations should prioritize immediate patch deployment across all affected systems, particularly those with exposed RDP services. Network-level controls including firewall rules that restrict RDP access to trusted IP addresses, implementation of VPNs for remote access, and deployment of RDP-specific security solutions can provide additional layers of protection. The vulnerability also highlights the importance of network segmentation and principle of least privilege, as limiting RDP access to only necessary systems reduces the potential attack surface. Security monitoring should include detection of unusual RDP connection patterns and abnormal data flows that might indicate exploitation attempts. Organizations should also consider implementing multi-factor authentication for RDP access and regular security assessments to identify and remediate similar vulnerabilities in their remote access infrastructure.