Heap Out-of-Bounds Write in RTMPDump librtmp

Executive Summary

librtmp in RTMPDump through 2.6 has an out-of-bounds read and heap out-of-bounds write vulnerability. AMF3_Decode fails to handle AMF3 property decode failures properly. Malicious RTMP servers or attackers can send oversized AMF3 string lengths, causing heap memory corruption and leaks when the token option DecodeTEA is used.

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Detection Guidance

To detect this vulnerability, monitor network traffic for RTMP connections using tools like Wireshark or tcpdump to inspect AMF3 message formats. Check for oversized string lengths or malformed RTMP messages. Inspect librtmp versions in use; vulnerable versions are from December 2015 to present. Review logs for crashes or memory corruption errors in applications using librtmp.

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Impact Analysis

If you use software relying on librtmp (e.g., FFmpeg, VLC), a malicious RTMP server or man-in-the-middle attacker could exploit this to corrupt memory, crash applications, or leak sensitive data. Systems using the token option with DecodeTEA are at higher risk.

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Compliance Impact

This vulnerability could lead to unauthorized memory access, potentially exposing sensitive data. For GDPR, this may violate principles of data protection and confidentiality. For HIPAA, it could risk protected health information exposure. Compliance may be impacted if exploited.

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Mitigation Strategies

Immediately update librtmp to the latest patched version if available. Disable RTMP connections to untrusted servers. If using applications like FFmpeg or VLC, ensure they use updated librtmp builds. Monitor for suspicious RTMP traffic and block malicious IPs. Consider disabling the token option in RTMP configurations to prevent DecodeTEA exploitation.

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