Payroll Pirate: Failed OfficeHome Auth with iOS User-Agent (ResultType 90014)
This rule detects failed Microsoft 365 sign-in attempts on the OfficeHome application associated with error code 90014, indicating a malformed or missing credential payload. The detection specifically triggers when these failures originate from an iPhone/iOS user-agent. This behavior is indicative of the reconnaissance phase of the Payroll Pirate campaign (associated with threat actor Storm-2755), where attackers use mobile-simulated browsers from carrier IP ranges to probe authentication endpoints before deploying Adversary-in-the-Middle (AiTM) kits.
Microsoft Sentinel (KQL)
