alert http $HOME_NET any -> $EXTERNAL_NET any (msg:"ET MALWARE Win32/Atomsilo Ransomware Activity (POST)"; flow:established,to_server; http.method; content:"POST"; http.uri; content:".php"; endswith; http.user_agent; content:"Microsoft"; bsize:9; http.request_body; content:"blocknum="; startswith; fast_pattern; content:"&computername="; distance:0; content:"&base64privkey="; distance:0; content:"&base64pubkey="; distance:0; reference:md5,17b447b971a4977b2bfb2c28659aa1dd; reference:url,www.sentinelone.com/blog/living-off-windows-defender-lockbit-ransomware-sideloads-cobalt-strike-through-microsoft-security-tool/; classtype:trojan-activity; sid:2038577; rev:1; metadata:attack_target Client_Endpoint, created_at 2022_08_22, deployment Perimeter, malware_family LockBit, malware_family AtomSilo, confidence High, signature_severity Major, tag Ransomware, tag Description_Generated_By_Proofpoint_Nexus, updated_at 2022_08_22, mitre_tactic_id TA0040, mitre_tactic_name Impact, mitre_technique_id T1486, mitre_technique_name Data_Encrypted_for_Impact;)