alert http $HOME_NET any -> $EXTERNAL_NET any (msg:"ET MALWARE Win32/TrickBot maserv Module Command"; flow:to_server,established; http.method; content:"GET"; http.uri; content:"/mass/"; depth:30; fast_pattern; pcre:"/^(?:81|freq|domains|over|rate|npcap\.exe)\/?\s*[^\/]*$/si"; http.content_type; content:"application/x-www-form-urlencoded"; bsize:33; http.header_names; content:!"Referer"; reference:url,www.kryptoslogic.com/blog/2021/02/trickbot-masrv-module/; reference:md5,ff57c02b09cd9df4d1cac5090e01a5d2; classtype:trojan-activity; sid:2031600; rev:1; metadata:affected_product Windows_XP_Vista_7_8_10_Server_32_64_Bit, attack_target Client_Endpoint, created_at 2021_02_02, deployment Perimeter, malware_family TrickBot, confidence High, signature_severity Major, tag Description_Generated_By_Proofpoint_Nexus, updated_at 2021_02_02;)