How does Endpoint Detection use the MITRE ATT&CK Framework?

MITRE ATT&CK is an open-source taxonomy of adversary tactics, techniques, and procedures based on real-world observations. Increasingly, organizations leverage ATT&CK technique "coverage" as the basis for evaluating their security posture, while Endpoint Detection and Response (EDR) and Security Indicator and Event Management (SIEM) products integrate ATT&CK into their design as well as marketing. However, the extent to which ATT&CK coverage is suitable to serve as a security metric remains unclear-Does ATT&CK coverage vary meaningfully across different products? Is it possible to achieve total coverage of ATT&CK? Do endpoint products that detect the same attack behaviors even claim to cover the same ATT&CK techniques? In this work, we attempt to answer these questions by conducting a comprehensive (and, to our knowledge, the first) analysis of endpoint detection products' use of MITRE ATT&CK. We begin by evaluating 3 ATT&CK-annotated detection rulesets from major commercial providers (Carbon Black, Splunk, Elastic) and a crowdsourced ruleset (Sigma) to identify commonalities and underutilized regions of the ATT&CK matrix. We continue by performing a qualitative analysis of unimplemented ATT&CK techniques to determine their feasibility as detection rules. Finally, we perform a consistency analysis of ATT&CK labeling by examining 37 specific threat entities for which at least 2 products include specific detection rules. Combined, our findings highlight the limitations of overdepending on ATT&CK coverage when evaluating security posture; most notably, many techniques are unrealizable as detection rules, and coverage of an ATT&CK technique does not consistently imply coverage of the same real-world threats.