CVE-2017-2837 in FreeRDP
Summary
by MITRE
An exploitable denial of service vulnerability exists within the handling of security data in FreeRDP 2.0.0-beta1+android11. A specially crafted challenge packet can cause the program termination leading to a denial of service condition. An attacker can compromise the server or use man in the middle to trigger this vulnerability.
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Analysis
by VulDB Data Team • 03/07/2023
The vulnerability identified as CVE-2017-2837 represents a critical denial of service weakness within the FreeRDP 2.0.0-beta1+android11 implementation that specifically targets the security data handling mechanisms. This flaw manifests during the processing of challenge packets within the Remote Desktop Protocol stack, where improper input validation leads to program termination. The vulnerability operates at the protocol level where FreeRDP encounters malformed security data during authentication exchanges, creating a condition where legitimate service operations are disrupted through controlled input manipulation.
This security flaw stems from inadequate bounds checking and input sanitization within the RDP security negotiation phase, particularly affecting the challenge packet processing logic. The technical implementation fails to properly validate the length and content of incoming security data structures, allowing maliciously crafted packets to trigger memory corruption or invalid memory access conditions. According to CWE classification, this vulnerability maps to CWE-125: Out-of-bounds Read, as the application attempts to process security data beyond its allocated buffer boundaries. The flaw exists in the cryptographic handshake process where FreeRDP validates server challenges during authentication, making it particularly dangerous in networked environments where authentication servers are exposed to untrusted clients.
The operational impact of CVE-2017-2837 extends beyond simple service disruption, as it provides attackers with potential man-in-the-middle capabilities that can be leveraged for more sophisticated attacks. When exploited, the vulnerability can cause immediate termination of the FreeRDP service, effectively denying legitimate users access to remote desktop services. The attack vector requires minimal privileges and can be executed remotely, making it particularly attractive for automated exploitation campaigns. Network administrators face significant operational challenges as this vulnerability can be triggered without requiring authentication, allowing attackers to perform denial of service attacks against RDP servers that are not properly secured or monitored. The vulnerability also creates opportunities for attackers to establish persistent access points through session hijacking or credential harvesting, as the service interruption can be used as a precursor to more complex attack chains.
Mitigation strategies for this vulnerability should encompass multiple layers of defense including immediate patch deployment, network segmentation, and enhanced monitoring of RDP traffic. Organizations must prioritize updating to FreeRDP versions that have addressed this specific flaw, as the vulnerability affects the core authentication mechanisms that are fundamental to remote desktop operations. Network-based protections should include implementing strict access controls that limit RDP service exposure to trusted networks only, while also deploying intrusion detection systems that can identify and alert on suspicious challenge packet patterns. From an ATT&CK framework perspective, this vulnerability aligns with T1071.004: Application Layer Protocol: Remote Desktop Protocol, and T1499.004: Network Denial of Service, indicating that defensive measures should address both the protocol-level exploitation and the broader denial of service implications. Additionally, implementing proper logging and monitoring of authentication events can help detect exploitation attempts before they cause service disruption, while network access control lists can be configured to restrict RDP service access to authorized endpoints only.