alert http $HOME_NET any -> $EXTERNAL_NET any (msg:"ET MALWARE Sekhmet Ransomware CnC Activity"; flow:established,to_server; http.start; content:"POST /update.php?id="; startswith; fast_pattern; pcre:"/^\d+\sHTTP\//R"; http.user_agent; bsize:34; content:"Mozilla/4.0 (compatible|3b| MSIE 6.0)"; http.request_body; pcre:"/^(?:[A-Za-z0-9+/]{4})*(?:[A-Za-z0-9+/]{2}==|[A-Za-z0-9+/]{3}=|[A-Za-z0-9+/]{4})\x00$/"; reference:url,twitter.com/fbgwls245/status/1241179394405621760; reference:md5,b7ad5f7ec71dc812b4771950671b192a; classtype:command-and-control; sid:2029728; rev:1; metadata:affected_product Windows_XP_Vista_7_8_10_Server_32_64_Bit, attack_target Client_Endpoint, created_at 2020_03_23, deployment Perimeter, confidence High, signature_severity Major, tag Ransomware, tag Description_Generated_By_Proofpoint_Nexus, updated_at 2020_03_23, mitre_tactic_id TA0040, mitre_tactic_name Impact, mitre_technique_id T1486, mitre_technique_name Data_Encrypted_for_Impact;)