Uncontrolled Resource Consumption in FreeRDP Proxy via DVC Message Reassembly

Executive Summary

FreeRDP versions from 3.0.0 to 3.32.2 have an issue where the proxy component does not properly limit memory usage when handling intercepted DVC messages. Attackers can exploit this by sending fragmented messages with large declared sizes but incomplete data, causing the proxy to consume increasing amounts of heap memory proportional to traffic. This leads to resource exhaustion and degraded service.

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Detection Guidance

Monitor FreeRDP proxy memory usage for unexpected growth during client connections. Check for incomplete DVC message reassembly attempts or fragmented traffic patterns. Use system monitoring tools like top, htop, or ps to observe memory consumption by FreeRDP processes.

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Impact Analysis

If you use FreeRDP proxy in versions 3.0.0 to 3.32.2, an attacker could exploit this to consume excessive server memory, causing slowdowns or crashes. This may disrupt remote desktop services and require manual intervention to recover.

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Mitigation Strategies

Upgrade FreeRDP to version 3.32.2 or later. Disable the proxy feature if not required. Implement network traffic monitoring to detect and block suspicious fragmented DVC message patterns. Restrict client access to the proxy service.

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