alert http $HOME_NET any -> $EXTERNAL_NET any (msg:"ET MALWARE Observed 3CX Supply Chain Attack Cookie"; flow:to_server,established; http.cookie; content:"__tutma="; startswith; fast_pattern; reference:url,www.volexity.com/blog/2023/03/30/3cx-supply-chain-compromise-leads-to-iconic-incident/; reference:url,twitter.com/patrickwardle/status/1641699867176374273; reference:url,objective-see.org/blog/blog_0x73.html; classtype:trojan-activity; sid:2044848; rev:1; metadata:attack_target Client_Endpoint, created_at 2023_03_31, deployment Perimeter, deployment SSLDecrypt, performance_impact Low, confidence High, signature_severity Major, tag Description_Generated_By_Proofpoint_Nexus, updated_at 2023_03_31, reviewed_at 2024_05_07; target:src_ip;)