Out-of-Bounds Read in FreeRDP Client

Executive Summary

FreeRDP before version 3.31.0 has an out-of-bounds read flaw in the rdpdr_dump_packet function. This happens because a 32-bit unsigned integer can wrap around during buffer bounds validation. A malicious RDP server can exploit this by sending a specially crafted RDPDR packet with computerNameLen set to 0xFFFFFFF0. This bypasses normal checks and allows reading memory outside the intended packet buffer, potentially causing client crashes or exposing heap data in logs.

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Detection Guidance

Detecting this vulnerability requires monitoring for crashes or heap disclosure logs in FreeRDP clients when interacting with untrusted RDP servers. Check FreeRDP logs for segmentation faults or memory access errors during RDP sessions. Use network monitoring tools to inspect RDPDR packets for malformed computerNameLen values.

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Impact Analysis

If you use FreeRDP before 3.31.0, a malicious RDP server could crash your client application or leak sensitive memory contents through logs. This might expose internal data or disrupt your remote desktop sessions. The impact depends on your environment and whether you connect to untrusted RDP servers.

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Compliance Impact

This vulnerability could potentially impact compliance with GDPR and HIPAA by enabling unauthorized memory disclosure or crashes during RDP sessions. A malicious server exploiting this flaw might access sensitive data in memory logs or cause service disruptions, which could violate data protection requirements under GDPR (e.g., integrity and confidentiality principles) or HIPAA (e.g., safeguarding protected health information).

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Mitigation Strategies

Upgrade FreeRDP to version 3.31.0 or later. Avoid connecting to untrusted RDP servers. Implement network-level controls to block or inspect RDPDR traffic. Monitor vendor advisories for patches or workarounds.

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