CVE-2017-2835 in FreeRDP
Summary
by MITRE
An exploitable code execution vulnerability exists in the RDP receive functionality of FreeRDP 2.0.0-beta1+android11. A specially crafted server response can cause an out-of-bounds write resulting in an exploitable condition. An attacker can compromise the server or use a 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-2017-2835 represents a critical code execution flaw within the Remote Desktop Protocol implementation of FreeRDP version 2.0.0-beta1+android11. This issue manifests in the RDP receive functionality where the software fails to properly validate incoming data from remote servers, creating a pathway for malicious actors to exploit the system. The vulnerability stems from inadequate bounds checking mechanisms that allow crafted server responses to trigger memory corruption conditions. The flaw specifically enables an out-of-bounds write operation that can be leveraged to execute arbitrary code on the affected system, making it particularly dangerous for remote desktop services that rely on FreeRDP implementations.
The technical nature of this vulnerability aligns with CWE-787, which describes out-of-bounds write conditions that occur when a program writes data past the end of a buffer or array. This particular implementation flaw occurs during the processing of RDP server responses where the FreeRDP client does not properly validate the length or content of received data structures. When a malicious server sends specially crafted data packets, the client's receive function fails to enforce proper boundary checks, allowing memory corruption that can be exploited through carefully constructed input sequences. The vulnerability's exploitation potential is significantly amplified by the fact that it can be triggered through man-in-the-middle attacks, where an attacker intercepts and modifies RDP communication between legitimate parties.
The operational impact of CVE-2017-2835 extends beyond simple privilege escalation to encompass complete system compromise capabilities. An attacker who successfully exploits this vulnerability can execute arbitrary code with the privileges of the affected FreeRDP process, which typically runs with elevated permissions on the target system. This condition allows for persistent access, data exfiltration, and further network reconnaissance activities. The vulnerability affects any system running FreeRDP 2.0.0-beta1+android11 that accepts RDP connections from untrusted sources, making it particularly concerning for enterprise environments that utilize FreeRDP for remote access solutions. The man-in-the-middle attack vector increases the attack surface significantly as it requires no direct access to the target system, enabling remote exploitation from any location where network traffic can be intercepted or redirected.
Mitigation strategies for this vulnerability should prioritize immediate patching of affected FreeRDP installations to version 2.0.0-rc1 or later, which contains the necessary fixes for the out-of-bounds write condition. Network administrators should implement strict access controls and firewall rules to limit RDP access to trusted networks only, while also deploying intrusion detection systems that can identify suspicious RDP traffic patterns. The implementation of network segmentation and monitoring protocols can help detect potential exploitation attempts before they succeed. Security professionals should also consider disabling unnecessary RDP features and implementing additional authentication layers such as multi-factor authentication to reduce the attack surface. Organizations utilizing FreeRDP should conduct comprehensive vulnerability assessments to identify all systems running affected versions and establish incident response procedures specifically tailored to address potential exploitation of this vulnerability, as outlined in the mitre ATT&CK framework's techniques for privilege escalation and remote code execution.