CVE-2023-40569 in FreeRDP
Summary
by MITRE • 09/01/2023
FreeRDP is a free implementation of the Remote Desktop Protocol (RDP), released under the Apache license. Affected versions are subject to an Out-Of-Bounds Write in the `progressive_decompress` function. This issue is likely down to incorrect calculations of the `nXSrc` and `nYSrc` variables. This issue has been addressed in versions 2.11.0 and 3.0.0-beta3. Users are advised to upgrade. there are no known workarounds for this vulnerability.
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Analysis
by VulDB Data Team • 02/16/2025
CVE-2023-40569 represents a critical out-of-bounds write vulnerability within FreeRDP's progressive_decompress function that poses significant security risks to remote desktop implementations. This vulnerability specifically affects versions of FreeRDP prior to 2.11.0 and 3.0.0-beta3, making it a substantial concern for organizations relying on remote desktop protocols for secure access. The flaw manifests in the incorrect calculation of nXSrc and nYSrc variables during the decompression process, which directly leads to memory corruption when the application attempts to write data beyond the allocated buffer boundaries. Such memory corruption vulnerabilities are classified under CWE-787, which specifically addresses out-of-bounds write conditions that can result in arbitrary code execution or system instability.
The technical implementation of the progressive_decompress function in FreeRDP processes compressed graphics data from remote desktop connections, where the nXSrc and nYSrc variables represent source coordinates for decompression operations. When these variables are miscalculated due to improper bounds checking or arithmetic operations, the decompression routine attempts to write data to memory locations that are outside the intended buffer allocation. This condition creates a predictable attack surface where malicious actors can craft specially crafted RDP packets that trigger the buffer overflow when processed by vulnerable FreeRDP implementations. The vulnerability's exploitation potential is heightened because RDP is widely used for enterprise remote access, making this a prime target for attackers seeking persistent access to corporate networks.
From an operational perspective, this vulnerability presents a severe risk to organizations utilizing FreeRDP for remote desktop services, particularly those operating in environments where network segmentation is insufficient or where RDP is exposed to untrusted networks. The absence of known workarounds means that affected systems cannot be protected through configuration changes or temporary patches, leaving them fully exposed until the mandatory upgrade to patched versions occurs. Attackers could leverage this vulnerability to execute arbitrary code on systems running vulnerable FreeRDP implementations, potentially leading to complete system compromise, data exfiltration, or establishment of persistent backdoors. The impact extends beyond individual system compromise to potential lateral movement within networks where RDP is used for administrative access, creating cascading security implications.
Organizations should prioritize immediate upgrade to FreeRDP versions 2.11.0 or 3.0.0-beta3 to remediate this vulnerability, as these releases contain the necessary fixes for the miscalculated variable handling in the progressive_decompress function. Security teams should implement network monitoring to detect potential exploitation attempts through anomalous RDP traffic patterns or unusual decompression behavior. The vulnerability's classification aligns with ATT&CK technique T1071.004, which covers application layer protocol usage for remote access, and T1059.007, covering command and scripting interpreter usage through remote access tools. Additional mitigations should include implementing network access controls to restrict RDP access to trusted networks, enabling multi-factor authentication for RDP connections, and conducting thorough vulnerability assessments of all systems utilizing FreeRDP for remote desktop functionality to ensure complete remediation of this and related memory corruption vulnerabilities.