alert http $HOME_NET any -> $EXTERNAL_NET any (msg:"ET MALWARE Lyceum Golang HTTP Backdoor Connectivity Check"; flow:established,to_server; http.request_line; content:"POST /GO/"; fast_pattern; content:".php"; endswith; http.accept_enc; bsize:1; content:"*"; http.content_len; bsize:1; content:"0"; reference:url,research.checkpoint.com/2022/state-sponsored-attack-groups-capitalise-on-russia-ukraine-war-for-cyber-espionage/; classtype:command-and-control; sid:2035957; rev:3; metadata:affected_product Windows_XP_Vista_7_8_10_Server_32_64_Bit, attack_target Client_Endpoint, created_at 2022_04_14, deployment Perimeter, confidence High, signature_severity Major, tag Backdoor, tag Description_Generated_By_Proofpoint_Nexus, updated_at 2023_03_10;)