There is disclosed in one example a computer-implemented method of detecting a statistically-significant security event and automating a response thereto, including: querying, or causing to be queried, a security intelligence database for sector-wise historical norms for an indicator of compromise (IoC); obtaining sector-wise expected prevalence data for the IoC; receiving observed sector-wise prevalence data for the IoC; computing a first test statistic from a goodness-of-fit test between the observed and expected prevalences; from the observed sector-wise prevalence data, computing a second test statistic from a difference between a highest prevalence and a next-highest prevalence; computing a third test statistic from a difference between the observed prevalence of a highest prevalence sector and the expected prevalence for the highest prevalence sector; selecting a least significant statistic from among the first, second, and third test statistics; and determining from the least significant statistic whether to notify a subscriber.