This year, US agencies rushed to implement Domain-based Message, Authentication, Reporting and Conformance (DMARC) protocols by a deadline mandated by the Department of Homeland Security. So, when the Global Cyber Alliance published research that 18 email domains managed by the Executive Office of the President were not using DMARC after that deadline had passed, the reaction was to lament the slow-moving agencies and criticize them for leaving their employees vulnerable to phishing attacks.

However, the fact that the federal government hasn't been implementing DMARC as it should be has far fewer implications for data privacy and the overall national security of the United States than the report and ensuing headlines would let on —  although that doesn't mean securing email shouldn't be taken seriously.

It's important to first understand DMARC's functionality within email security. Simply put, DMARC checks for alignment between the apparent sender of a message and its DomainKeys Identified Mail (DKIM) and Sender Policy Framework (SPF) headers, and then provides instructions to recipients on handling messages that display misalignment. This presupposes that recipients are checking DMARC records, and that senders are providing accurate information to check against. Although proper implementation and enforcement of DMARC can be helpful for preventing phishing attacks where your organization's brand is impersonated to consumers and business partners, it does very little to protect against inbound spear-phishing attacks.

The reason is largely due to what DMARC was designed to accomplish. DMARC effectively serves as a means for the recipient to verify that the sender is who they purport to be. But other than protecting one's own brand against such impersonation, the purported sending organization (in this case, the federal government) is not much further protected from phishing and social engineering attacks intended to steal credentials, personally identifiable information, or other information. There are many highly accessible avenues for these threat actors interested in targeting the government.

For example, many attacks do not impersonate someone at the target's organization with their exact email address. Spoofing attacks may instead employ subtle tricks that go unnoticed by an overworked government employee—whether by using a domain similar to a trusted vendor or partner or impersonating a citizen. Just think about the sheer number of people these organizations interact with and how many "I am Jane Q, please review my document to see how you can help me with my pet project" emails they receive on a daily basis.

This is not to entirely write off DMARC. But although it is true that it would be significantly more difficult for phishers to effectively spoof a domain if every organization implemented DMARC, that goal is not attainable in the short-term, nor would it completely safeguard email users.

Even in a world where proper DMARC implementation is scoped to only the federal agencies in question, the organizations would still be exposed to attacks impersonating potentially any organization that has not implemented DMARC and could even potentially still have exposure to attacks impersonating organizations that do have DMARC implemented. This also says nothing of attacks originating from Gmail, Yahoo, and other email service providers, as well as mail being sent from various other domains. DMARC is only as strong as the sum of its parts, and some of those parts are entirely outside of the purview of the federal government.

This is important as it relates to DMARC and organizations the federal government works with, because it's no secret that external partners have been a major source of data leaks from the government. This means that sensitive government information is only as secure as the security practices used by federal IT contractors. A recent study showed that 49 of the top 50 government IT contractors are also not using DMARC, which puts the government at risk for responding to emails purportedly from those contractors.

The disproportionate focus on DMARC camouflages the fact that there are other core risk factors the government should be addressing if they're serious about improving their email security. In fact, the sophisticated spoofing attacks DMARC is intended to stop represent a relatively small percentage of overall phishing attacks that rely on other, simpler (yet equally effective), vectors. 

Instead, every SMTP communication contains a number of data points: correlation of sending domain and return path, reply-to and IP address(es), sender relationship, and a variety of others that are available for analysis. Malicious or suspicious communications can and should be identified by these types of factors rather than relying entirely on the enforcement of DMARC.

The federal government is similar to many enterprises in that it faces challenges in both expertise and resources. The average business receives approximately 3,680 emails with threat characteristics per week – most of which are unaffected by DMARC protocols. In addition to DMARC, government agencies need to implement automated policies that reduce the organization's reliance on their employees having to proactively identify phishing techniques.

It's not surprising agencies are operating slowly to adopt new standards, but it is encouraging to see the government make email security a priority as it is the most prevalent, and arguably most effective, tool within the arsenal of cybercriminals. While the implementation of DMARC is important, its immediate implementation does little to either increase or decrease the government's susceptibility to cyber espionage. 

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