alert http any any -> [$HOME_NET,$HTTP_SERVERS] any (msg:"ET EXPLOIT Microsoft Exchange - Information Disclosure flowbit set (CVE-2021-33766)"; flow:established,to_server; http.uri; content:"/ecp/"; nocase; fast_pattern; http.cookie; content:"SecurityToken="; flowbits:set,ET.proxytoken; reference:cve,2021-33766; classtype:attempted-admin; sid:2033834; rev:1; metadata:attack_target Server, created_at 2021_08_30, cve CVE_2021_33766, deployment Perimeter, deployment Internal, confidence High, signature_severity Major, tag Exploit, tag CISA_KEV, updated_at 2021_08_30, mitre_tactic_id TA0001, mitre_tactic_name Initial_Access, mitre_technique_id T1190, mitre_technique_name Exploit_Public_Facing_Application;)