alert tcp $HOME_NET any -> $EXTERNAL_NET any (msg:"ET MALWARE Houdini/Hworm CnC Checkin M1"; flow:established,to_server; content:"new_houdini|0d 0a|"; fast_pattern; offset:4; depth:13; content:"|0d 0a|"; distance:0; content:"|0d 0a|"; distance:0; content:"|0d 0a|"; endswith; reference:md5,45009c70d362dcd253112c9cf1924f57; reference:url,researchcenter.paloaltonetworks.com/2016/10/unit42-houdinis-magic-reappearance; classtype:command-and-control; sid:2023429; rev:3; metadata:affected_product Windows_XP_Vista_7_8_10_Server_32_64_Bit, attack_target Client_Endpoint, created_at 2016_10_26, deployment Perimeter, malware_family Houdini, malware_family Hworm, performance_impact Low, confidence High, signature_severity Major, updated_at 2019_09_28;)