alert http $HOME_NET any -> $EXTERNAL_NET any (msg:"ET MALWARE MirrorBlast KiXtart Downloader Client Request M2"; flow:established,to_server; http.request_line; content:"GET /?data="; startswith; fast_pattern; content:!"="; distance:0; content:"|3a|"; within:17; content:"|3a|"; distance:0; isdataat:!261; http.header_names; content:"|0d 0a|Accept|0d 0a|"; startswith; content:"|0d 0a|Accept-Encoding|0d 0a|User-Agent|0d 0a|Host|0d 0a|Connection|0d 0a 0d 0a|"; endswith; content:!"|0d 0a|Referer|0d 0a|"; reference:md5,8b6199f5d5465c327c8c30ac9fdfd23a; classtype:command-and-control; sid:2034136; rev:2; metadata:affected_product Windows_XP_Vista_7_8_10_Server_32_64_Bit, attack_target Client_Endpoint, created_at 2021_10_06, deployment Perimeter, malware_family MirrorBlast, performance_impact Moderate, confidence High, signature_severity Major, tag Description_Generated_By_Proofpoint_Nexus, updated_at 2021_10_06;)