Heap Buffer Overflow in FreeRDP via Malicious RDP Clipboard

Executive Summary

FreeRDP versions 3.10.0 through 3.32.2 have a heap buffer overflow in the PNG conversion process. When a realloc fails during clipboard image processing, the code writes past the allocated buffer. Attackers can exploit this by sending a large CF_DIB image via RDP clipboard, causing an out-of-bounds memcpy and client crash.

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Detection Guidance

Check FreeRDP version with 'xfreerdp --version' or 'apt list --installed | grep freerdp'. Monitor for crashes during clipboard operations with PNG images. Enable verbose logging in FreeRDP with '-v' flag to detect heap corruption errors.

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Impact Analysis

This vulnerability allows a malicious RDP clipboard peer to crash the FreeRDP client by sending a specially crafted image. The crash occurs due to memory corruption from the heap buffer overflow, potentially leading to denial of service for the affected FreeRDP session.

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Compliance Impact

This vulnerability primarily causes client crashes due to heap buffer overflow during PNG conversion of clipboard images. It does not directly impact data confidentiality, integrity, or availability in a way that would violate GDPR or HIPAA compliance requirements. However, if exploited, it could lead to denial-of-service conditions affecting system availability.

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Mitigation Strategies

Upgrade FreeRDP to version 3.32.0 or later. Disable clipboard sharing in RDP connections if not required. Block external clipboard data transfers at the network level. Monitor for suspicious clipboard activity involving large image transfers.

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