Luis Rodríguez, CTO of Xygeni.io, discusses a recent SSH backdoor attack that posed a threat to over 20 million servers. He details how the malicious code was inserted via a compromised compression library and the sophisticated social engineering employed by the attacker. The conversation highlights the limitations of traditional exploit detection methods and the implications for open source security. Rodríguez emphasizes the importance of community vigilance in identifying legitimate contributions to prevent future incidents.
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Quick takeaways
The attempted SSH backdoor attack highlighted the need for vigilant contributors in software communities, as even non-security specialists can uncover vulnerabilities.
The incident demonstrated the effectiveness of social engineering in manipulating open-source repository maintainers, underscoring the necessity for stricter oversight and security measures.
Deep dives
Overview of the Supply Chain Attack
A significant supply chain attack involved the introduction of a backdoor in a popular Linux compression library, LCMA. This backdoor was eventually embedded into OpenSSH, resulting in malicious command execution capabilities. The attack exemplified advanced techniques, including the use of obfuscation to evade detection from reviewers, ultimately affecting potentially over 20 million OpenSSH servers. Fortunately, the issue was identified and contained quickly, preventing further distribution and potential exploitation.
Detection Process and Key Findings
The backdoor was detected by a PostgreSQL developer who noticed unusual performance issues within the SSH server. His investigation revealed that a library was modifying the system library function table, leading to the discovery of obfuscated code intended for command execution by an attacker. Remarkably, this critical finding was made by an individual who did not specialize in security, highlighting the role of observant developers in catching such vulnerabilities. This incident underscores the importance of having vigilant contributors in software development communities to identify and address anomalies.
Attacker's Methodology and Social Engineering
The investigation into the attack revealed that the perpetrators employed social engineering tactics to gain trust and commit changes within the repository. Fake identities were used to manipulate the maintainer, gaining significant access over an extended period with innocuous contributions. This deceptive approach enabled the attackers to introduce malicious code strategically, demonstrating the complexities of maintaining open-source security. The attackers’ patience in cultivating trust before executing their plan emphasized the need for stringent oversight within open-source projects.
Lessons Learned and Future Implications
The incident raised critical discussions regarding vulnerabilities within open-source protocols and the need for enhanced security measures. Following this event, immediate changes were proposed to remove unnecessary dependencies and tighten the governance surrounding contributions to open-source projects. The attack revealed that typical detection methods may be insufficient against sophisticated threats, prompting a re-evaluation of how software is compiled and managed. This situation serves as a wake-up call for the community to bolster vigilance and implement stricter protocols that can prevent such insidious attacks in the future.
Luis Rodríguez, CTO of Xygeni.io, joins host Robert Blumen for a discussion of the recently thwarted attempt to insert a backdoor in the SSH (Secure Shell) daemon. OpenSSH is a popular implementation of the protocol used in major Linux distributions for authentication over a network. Luis describes how a backdoor in a supporting library was recently discovered and removed before the package was published to stable releases of the Linux distros. The conversation explores the mechanism of the attack through modifying a function table in the runtime; how the attack was inserted during the build; how the attack was carefully staged in a series of modifications to the lz compression library; the nature of “Jia Tan,” the entity who committed the changes to the open source project; social engineering that the entity used to gain the trust of the open source community; what forensics indicates about the location of the entity; hypotheses about whether criminal or state actors backed the entity; how the attack was detected; implications for other open source projects; why traditional methods for detecting exploits would not have helped find this; and lessons learned by the community.