Authentication Coercion: Abusing Rare Windows RPC Interfaces
🔒 Unit 42 details how attackers force Windows hosts to authenticate to attacker-controlled systems by abusing rarely monitored RPC interfaces. The report explains techniques, including misuse of UNC path parameters and obscure opnums, and reviews a March 2025 healthcare incident that leveraged MS-EVEN ElfrOpenBELW. It outlines indicators such as bursts of failed NTLM authentications and RPC calls containing external UNC targets. Recommendations include detection, RPC filtering, SMB signing, and Cortex XDR protections.
