Microsoft Threat Intelligence Podcast

Behind the Scenes of the XZ vuln with Andres Freund and Thomas Roccia

May 8, 2024

Andres Freund and Thomas Roccia discuss discovering a backdoor in the XZ package, emphasizing proactive security measures and code review in open source. They highlight the importance of community collaboration in identifying and mitigating security threats effectively.

33:21

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Episode guests

Andres Freund

Thomas Roccia

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Episode notes

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Quick takeaways

Proactive security and code review are essential in the open-source community to detect sophisticated backdoors like in the XZ library.

Anomalies in software behavior should be investigated promptly as they could indicate hidden threats, emphasizing the need for community cooperation in threat identification.

Deep dives

Discovery of the Backdoor in XZ Library

Andreas Freund discovered a backdoor in the XZ library hidden in the LZMA library, impacting systems using open Ssh.H code. Despite its obfuscation, erratic CPU usage led to its detection during a profiling exercise. The backdoor's stealthy behavior raised red flags only during idle periods, evading notice on most systems.

Introduction

6min

Uncovering a Sophisticated Backdoor

21min

Exploring a Lucky Security Discovery and Lessons Learned

2min

Analyzing a Security Vulnerability and the Need for Proactive Measures in Open Source Projects

2min

Closing Remarks and Farewell from Guests

2min

On this week's episode of The Microsoft Threat Intelligence Podcast, Sherrod DeGrippo is joined by Thomas Roccia and Andres Freund. Andres stumbled upon a security issue within SSH while investigating performance discrepancies. He discovered a sophisticated backdoor, skillfully concealed within the LZMA library, part of the XZ package. Sherrod, Thomas, and Andres discuss the importance of proactive security measures and code review in the open-source community. They emphasize the critical role of community collaboration in identifying and mitigating security threats effectively and signal the need for heightened vigilance.

In this episode you’ll learn:

The importance of proactive security and code review in the open-source community
Why anomalies in software behavior should prompt curiosity and investigation
Open-source community cooperation is vital for spotting and addressing security risks

Some questions we ask:

Could you explain the security issue you found in SSH and its significance?
How serious is this threat, and what steps can organizations take to defend against it?
What advice do you have for open-source contributors?