alert http any any -> [$HOME_NET,$HTTP_SERVERS] [443,444] (msg:"ET EXPLOIT Possible Microsoft Exchange RCE Inbound M1 (CVE-2021-34473)"; flow:established,to_server; http.method; content:"POST"; http.uri; content:"/ews/exchange.asmx"; fast_pattern; http.request_body; content:"<s"; content:"SerializedSecurityContext>"; distance:0; content:"Message>"; distance:0; content:"Attachments>"; distance:0; content:"Content>"; distance:0; content:"|60 c2 ac c2 aa|"; distance:0; within:200; reference:cve,2021-34473; classtype:attempted-admin; sid:2033684; rev:3; metadata:affected_product Microsoft_Exchange, attack_target Server, created_at 2021_08_09, cve CVE_2021_34473, deployment Perimeter, deployment Internal, deployment SSLDecrypt, confidence Medium, signature_severity Major, tag Exploit, tag CISA_KEV, updated_at 2022_12_23, mitre_tactic_id TA0001, mitre_tactic_name Initial_Access, mitre_technique_id T1190, mitre_technique_name Exploit_Public_Facing_Application;)