The Kaminsky DNS vulnerability exploited a weakness in DNS resolvers' handling of NXDOMAIN responses (indicating a nonexistent domain). Attackers could forge responses for nonexistent subdomains, poisoning the resolver's cache with a malicious IP address. The small size of the DNS response ID field (16 bits) and predictable transaction IDs made it relatively easy for attackers to guess the correct ID, allowing the forged response to be accepted. This enabled them to redirect traffic intended for legitimate websites to malicious servers, facilitating phishing and other attacks. The vulnerability was mitigated by increasing the entropy of transaction IDs, making them harder to predict and forged responses less likely to be accepted.
A misconfigured DNS record for Mastercard went unnoticed for an estimated two to five years, routing traffic intended for a Mastercard authentication service to a server controlled by a third-party vendor. This misdirected traffic included sensitive authentication data, potentially impacting cardholders globally. While Mastercard claims no evidence of malicious activity or misuse of the data, the incident highlights the risk of silent failures in critical infrastructure and the importance of robust monitoring and validation. The misconfiguration involved an incorrect CNAME record, effectively masking the error and making it difficult to detect through standard monitoring practices. This situation persisted until a concerned individual noticed the discrepancy and alerted Mastercard.
HN commenters discuss the surprising longevity of Mastercard's DNS misconfiguration, with several expressing disbelief that such a basic error could persist undetected for so long, particularly within a major financial institution. Some speculate about the potential causes, including insufficient monitoring, complex internal DNS setups, and the possibility that the affected subdomain wasn't actively used or monitored. Others highlight the importance of robust monitoring and testing, suggesting that Mastercard's internal processes likely had gaps. The possibility of the subdomain being used for internal purposes and therefore less scrutinized is also raised. Some commenters criticize the article's author for lacking technical depth, while others defend the reporting, focusing on the broader issue of oversight within a critical financial infrastructure.
Summary of Comments ( 2 )
https://news.ycombinator.com/item?id=43170343
The Hacker News comments on the illustrated guide to the Kaminsky DNS vulnerability largely praise the clarity and helpfulness of the guide, especially its visual aids. Several commenters reminisce about dealing with the vulnerability when it was discovered, highlighting the urgency and widespread impact it had at the time. Some discuss technical details, including the difficulty of patching all affected DNS servers and the intricacies of the exploit itself. One commenter points out that the same underlying issue (predictable transaction IDs) has cropped up in other protocols besides DNS. Another emphasizes the importance of the vulnerability's disclosure and coordinated patching process as a positive example of handling security flaws responsibly. A few users also link to related resources, including Dan Kaminsky's own presentations on the vulnerability.
The Hacker News post titled "An illustrated guide to the Kaminsky DNS vulnerability (2008)" has several comments discussing various aspects of the vulnerability and its impact.
Several commenters praised the clarity and helpfulness of the illustrated guide, finding it much easier to understand than other explanations they had encountered. They appreciated the visual approach and how it broke down a complex topic into digestible parts. One commenter mentioned how valuable this guide was for educational purposes, making it easier to teach the vulnerability to others.
A significant portion of the discussion revolved around the practical implications of the vulnerability and the scramble to patch systems in 2008. Commenters shared anecdotes about the urgency of the situation and the widespread effort required to mitigate the risk. Some discussed the challenges of patching diverse systems and the pressure to act quickly. One commenter recounted their experience of being called in on a weekend to apply emergency patches. Another highlighted the importance of DNSSEC as a long-term solution.
Some comments delved into the technical details of the vulnerability, exploring aspects like the birthday paradox, the role of source port randomization, and the specific techniques used in the exploit. One commenter provided a more concise summary of the vulnerability, focusing on the key elements of the attack. Another discussed the difficulty of predicting transaction IDs due to the birthday paradox. Several commenters corrected or clarified technical details mentioned in other comments, ensuring accuracy in the discussion.
A few comments touched on Dan Kaminsky's role and contribution. They acknowledged his responsible disclosure and the collaborative effort to patch the vulnerability before it was widely exploited.
There's a thread discussing how the vulnerability highlighted the fragility of the internet infrastructure and the importance of security best practices. Some users discussed the implications for other protocols and the need for ongoing vigilance against similar vulnerabilities.
Finally, a few comments mentioned related vulnerabilities and attacks, expanding the scope of the discussion beyond the specific Kaminsky DNS vulnerability. One commenter pointed out how this incident paved the way for improvements in DNS security and served as a valuable learning experience for the industry.