CVE-2017-8673 in Windows
Summary
by MITRE
The Remote Desktop Protocol (RDP) implementation in Microsoft Windows 10 1703 allows an attacker to connect to a target system using RDP and send specially crafted requests, aka "Windows Remote Desktop Protocol (RDP) Denial of Service Vulnerability."
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Analysis
by VulDB Data Team • 01/08/2021
The vulnerability identified as CVE-2017-8673 represents a critical denial of service weakness within Microsoft Windows 10 version 1703 Remote Desktop Protocol implementation. This flaw specifically affects systems running the Windows 10 Creators Update where RDP functionality is enabled and accessible to remote attackers. The vulnerability stems from insufficient input validation within the RDP stack, allowing malicious actors to craft specially formatted requests that can cause the target system to become unresponsive or crash entirely. The attack vector is particularly concerning as it requires no authentication credentials to exploit, making it accessible to any attacker who can reach the target system's RDP port. This vulnerability exists in the core RDP protocol handling mechanism, which is fundamental to Windows remote administration capabilities and is widely deployed across enterprise environments where remote access is essential for system maintenance and management operations.
The technical nature of this vulnerability aligns with CWE-129, which describes improper validation of input boundaries, and specifically manifests as a buffer over-read condition within the RDP protocol parser. When an attacker sends malformed RDP packets containing crafted data structures, the vulnerable Windows 10 system processes these requests through its RDP service without adequate validation checks. The implementation flaw occurs during the processing of certain RDP control packets, particularly those related to connection initialization and authentication handshake procedures. The system attempts to parse these malformed requests without proper bounds checking, leading to memory corruption that ultimately results in service termination or complete system hang. This behavior represents a classic denial of service scenario where legitimate system functionality is disrupted through carefully constructed malicious input that exploits weaknesses in the protocol implementation rather than attempting to gain unauthorized access or execute arbitrary code.
The operational impact of CVE-2017-8673 extends beyond simple service disruption, as it can severely compromise enterprise network availability and business continuity. Organizations relying on Windows 10 systems for remote administration face potential downtime when this vulnerability is exploited, particularly in environments where RDP is used for critical maintenance tasks or emergency access scenarios. The vulnerability's accessibility without authentication makes it particularly dangerous in environments where RDP ports are exposed to the internet or where network segmentation is insufficient to protect these services. From an attack perspective, this vulnerability maps to multiple MITRE ATT&CK techniques including T1071.001 for application layer protocol usage and T1499.004 for network denial of service. The impact is especially severe for organizations that depend on remote access capabilities for critical infrastructure management, as an attacker could repeatedly exploit this vulnerability to maintain persistent disruption of services. Additionally, the vulnerability's presence in Windows 10 1703 creates a significant risk for organizations that have not yet deployed the relevant Microsoft security updates, as this version was widely deployed in enterprise environments during the period leading up to the vulnerability disclosure.
Organizations should implement immediate mitigations including deploying the Microsoft security update released in June 2017 as part of the patching cycle. Network segmentation strategies should be enforced to limit RDP access to trusted networks only, with proper firewall rules restricting access to RDP ports from unauthorized external sources. The principle of least privilege should be applied to RDP access, ensuring that only necessary personnel have access to these services. Monitoring and logging of RDP connection attempts should be enhanced to detect anomalous patterns that might indicate exploitation attempts. Additionally, organizations should consider disabling RDP access where possible and implementing alternative secure remote access solutions such as virtual private networks or secure access platforms. The vulnerability demonstrates the importance of maintaining current security patches and implementing network monitoring to detect potential exploitation attempts. Microsoft's recommended approach includes applying the security update KB4019472, which addresses the underlying RDP protocol handling flaw. Organizations should also review their remote access policies and ensure that RDP is not unnecessarily exposed to the internet, as this vulnerability is particularly dangerous in publicly accessible environments. The remediation process should include comprehensive testing of the patch in controlled environments before widespread deployment to ensure compatibility with existing systems and applications.