Memory Exhaustion in FreeRDP via DVC Message

Executive Summary

FreeRDP versions from 2.0.0 to 3.32.0 have a memory exhaustion vulnerability in the wts_read_drdynvc_data_first function. Authenticated clients can exploit this by sending a seven-byte DATA_FIRST message on an opened DVC channel, declaring a large 32-bit length. This forces the server to allocate large amounts of zeroed resident memory, leading to resource exhaustion.

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Detection Guidance

Detecting this vulnerability requires monitoring FreeRDP server memory usage and network traffic for suspicious DVC (Dynamic Virtual Channel) messages. Check for repeated seven-byte DATA_FIRST messages with large declared lengths. Use tools like tcpdump or Wireshark to capture and analyze RDP traffic for unusual patterns.

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Impact Analysis

This vulnerability can cause servers running affected FreeRDP versions to run out of memory, leading to crashes, degraded performance, or denial of service. Attackers with authenticated access could exploit it to disrupt services or force system failures.

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Compliance Impact

This vulnerability could potentially impact compliance with GDPR and HIPAA by enabling denial-of-service attacks that exhaust server resources, potentially disrupting availability of systems handling sensitive data. However, the provided CVE details do not explicitly address compliance implications.

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Mitigation Strategies

Immediately upgrade FreeRDP to version 3.32.0 or later. If upgrading is not possible, restrict network access to FreeRDP servers using firewalls or network segmentation. Monitor server memory usage closely and terminate suspicious connections.

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