DNS Abuse Rankings: The Shocking Discrepancy Between Open Source and Commercial Blocklists

The fight against DNS abuse is a constant arms race. Organizations worldwide are diligently working to identify and block malicious domains, protecting internet users from phishing attacks, malware distribution, and other harmful activities. A crucial component of this fight is the use of blocklists, also known as Real-time Blackhole Lists (RBLs), which contain lists of domains and IP addresses known to be associated with abusive behavior. However, a recent study has revealed a concerning discrepancy: the abuse rankings generated by open source blocklists often differ dramatically from those produced by commercial blocklists, potentially leaving significant blind spots in our DNS monitoring efforts. This article delves into this critical issue, exploring the reasons behind the discrepancy, its implications, and the steps we can take to address it.

Many research organizations dedicate their resources to compiling and publishing lists of top-level domains (TLDs) and domain registrars believed to have high rates of abuse. These lists serve as invaluable resources for security professionals and researchers seeking to understand and mitigate DNS abuse. However, the effectiveness of these lists is directly dependent on the quality and comprehensiveness of their underlying data. The accuracy of these lists is paramount to effective cybersecurity strategies.

ICANN (Internet Corporation for Assigned Names and Numbers), the organization responsible for coordinating the global DNS, recently released new data derived from its Domain Metrica system, which tracks a range of abuse metrics across the DNS landscape. This data sheds light on a critical issue that has been underappreciated until now: the significant divergence in abuse rankings depending on whether the data originates from open source or commercial blocklists.

ICANN’s findings reveal that commercial RBLs tend to identify and capture a greater volume of DNS abuse compared to their open source counterparts. This difference can be attributed primarily to the varying resources and motivations behind the maintenance of these lists. Commercial blocklists are typically maintained by for-profit companies that invest significant resources in data collection, analysis, and list maintenance. These companies often employ sophisticated techniques, such as honeypots, web crawlers, and machine learning algorithms, to identify and track abusive domains. In contrast, open source blocklists are often maintained by volunteers or non-profit organizations with limited resources. While these lists can be valuable, they may lack the same level of comprehensiveness and accuracy as commercial lists due to resource constraints.

The discrepancy between open source and commercial blocklists becomes particularly evident when comparing the rankings of specific TLDs. While the top two TLDs identified as having the highest rates of abuse may be consistent across both types of lists, the rankings of the remaining TLDs often diverge significantly. This suggests that open source blocklists may be missing a substantial portion of the abusive domains operating within certain TLDs.

Consider the following table, which illustrates the differences in TLD rankings between commercial and open source blocklists:

As the table illustrates, significant differences exist between the commercial and open-source rankings. TLD_8 is ranked 8th in commercial lists but 51st in open-source lists. This highlights the critical point that relying solely on open-source lists may result in a skewed perception of DNS abuse distribution across various TLDs.

These coverage discrepancies have real-world implications. They can affect the perceived reputations of registrars and registries, potentially leading to unfair or inaccurate assessments of their efforts to combat abuse. Furthermore, these discrepancies can skew our understanding of the effectiveness of different DNS abuse mitigation policies. If certain policies appear to be more effective based on data from open source blocklists, it may simply be because those lists are not capturing the full scope of abuse in certain areas.

ICANN emphasizes the need for a multi-faceted approach to DNS abuse measurement, stating:

In short, relying on a limited set of blocklists, especially open-source ones, can leave significant gaps in DNS Abuse coverage and skew interpretation. For researchers, policymakers, and industry stakeholders, the takeaway is clear: robust DNS Abuse measurement demands a multi-source approach, blending open and commercial RBLs. Only by acknowledging and addressing these blind spots can we build a more accurate, actionable view of the DNS Abuse landscape – and ensure that our metrics and responses truly reflect reality.

To effectively combat DNS abuse, it is essential to leverage a combination of open source and commercial blocklists. By integrating data from multiple sources, we can gain a more comprehensive and accurate understanding of the DNS abuse landscape. This multi-source approach will help us identify and address blind spots, improve the effectiveness of our mitigation policies, and ultimately protect internet users from malicious activities.

Furthermore, continued investment in both open source and commercial blocklist development is crucial. Open source blocklists provide a valuable resource for the community and can be particularly useful for smaller organizations with limited budgets. However, it is important to recognize the limitations of these lists and supplement them with data from commercial providers. Commercial blocklists, with their advanced data collection and analysis capabilities, can provide a more comprehensive view of the DNS abuse landscape. By supporting both types of blocklists, we can foster a more robust and resilient DNS ecosystem.

In conclusion, the significant discrepancy between open source and commercial blocklist rankings highlights the need for a more comprehensive and data-driven approach to DNS abuse monitoring. By adopting a multi-source strategy that incorporates data from both types of blocklists, we can mitigate blind spots, improve the effectiveness of our mitigation efforts, and create a safer online environment for everyone. The future of DNS security depends on our ability to acknowledge and address these challenges, working collaboratively to build a more secure and resilient DNS infrastructure. Continuous monitoring and data analysis are essential to adapting to the ever-evolving tactics of malicious actors.

Ultimately, the fight against DNS abuse is a shared responsibility. Researchers, policymakers, industry stakeholders, and individual users all have a role to play in ensuring the integrity and security of the DNS. By working together and embracing a data-driven approach, we can effectively combat DNS abuse and protect the internet from harm.