Remote Code Execution in FreeRDP

Executive Summary

FreeRDP versions before 3.0.0 and 3.6.0 before 3.32.0 have a flaw where uninitialized heap memory from un-decoded progressive tiles is rendered to the screen. A malicious RDP server sends crafted blocks (WBT_TILE_FIRST followed by WBT_TILE_UPGRADE) to exploit this, causing sensitive heap data to display as pixels or crash the client.

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Detection Guidance

To detect this vulnerability, check the FreeRDP version installed on your system. Run: freerdp2-shadow --version or apt list --installed | grep freerdp. If the version is below 3.0.0 or between 3.6.0 and 3.31.0, the system is vulnerable. Monitor network traffic for RDP connections using tools like Wireshark to inspect for WBT_TILE_FIRST and WBT_TILE_UPGRADE sequences.

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Impact Analysis

An attacker could expose sensitive memory contents on your screen or crash your FreeRDP client. This may lead to information leaks or denial of service if you connect to a malicious RDP server.

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Compliance Impact

This vulnerability could lead to unauthorized data exposure, potentially violating GDPR (data protection) or HIPAA (health information privacy) if sensitive data is leaked through the rendered heap memory.

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Mitigation Strategies

Immediately update FreeRDP to version 3.0.0 or later, or 3.32.0 or later if using the 3.6.x branch. Disable the progressive codec if updates are not possible by modifying client configuration files to disable tile decoding. Restrict RDP server connections to trusted hosts only.

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