Your ATT&CK Heatmap Is Counting Rules, Not Coverage
Every detection vendor ships a MITRE ATT&CK heatmap, and every one of them is mostly green. Broad coverage, techniques lit up across the board, a reassuring wall of color in the sales deck and the board slide. It's the universal flex. We cover the matrix. Then you parse the actual rules – the real YAML in the public repo, not the marketing layer on top of it – and the green collapses into three tactics. Everyone covers execution and persistence. Almost nobody covers discovery, lateral movement, or collection. The heatmap wasn't measuring coverage. It was counting rules, and counting them in a way designed to look complete. What a green cell actually means A green cell in a Navigator layer means one thing: at least one rule somewhere references that technique tag. That's it. Not "we detect this reliably." Not "this fires on real attacks and stays quiet otherwise." Not "this survives an attacker who knows the rule exists." One rule that names the technique in its metadata turns the cell green, and forty rules turn it the same shade. Unless the layer is scored by rule count – and most published heatmaps aren't – one and forty are indistinguishable. I've written before that an untested detection isn't a detection, it's a query that runs on a schedule. The heatmap is the same lie one level up. A green matrix isn't coverage. It's a wall of queries that run, rendered in a color that means "present," dressed up as a color that means "protected." The vendor knows the difference. The buyer staring at the green doesn't. You can measure the real shape yourself Here's the part the heatmap marketing depends on you not doing: the rules are public, and you can count them. SigmaHQ, Elastic's detection-rules, Splunk ESCU, Panther, Sublime – all on GitHub, all tagged with attack.TXXXX technique IDs and tactic tags in the rule metadata. The method is boring on purpose. Walk the rule directories. Pull the ATT&CK tags out of each rule. Aggregate by technique, roll the technique counts up