alert http any any -> $HOME_NET any (msg:"ET HUNTING Microsoft Exchange OWA Authenticated Unsigned JSON Web Token (JWT) Request M1"; flow:established,to_server; http.method; content:"POST"; http.uri; content:"/owa/service.svc|3f|action|3d|getaccesstokenforresource"; fast_pattern; startswith; nocase; http.header; content:"x-owa-urlpostdata|3a 20|"; nocase; pcre:"/^[^\x0d\x0a]*?(?:\x22|\x2522)[tT][oO][kK][eE][nN][rR][eE][qQ][uU][eE][sS][tT](?:\x3a|\x253[aA])(?:\x23|\x2523)[eE][xX][cC][hH][aA][nN][gG][eE]/R"; reference:url,i.blackhat.com/USA-19/Thursday/us-19-Jaiswal-Preventing-Authentication-Bypass-A-Tale-Of-Two-Researchers.pdf; classtype:web-application-activity; sid:2063643; rev:1; metadata:affected_product Microsoft_Exchange, attack_target Server, tls_state TLSDecrypt, created_at 2025_07_21, deployment Perimeter, deployment Internal, confidence Medium, signature_severity Major, tag Exploit, updated_at 2025_07_21, mitre_tactic_id TA0001, mitre_tactic_name Initial_Access, mitre_technique_id T1190, mitre_technique_name Exploit_Public_Facing_Application; target:dest_ip;)