alert http $HOME_NET any -> $EXTERNAL_NET any (msg:"ET MALWARE Dridex Post Check-in Activity"; flow:established,to_server; threshold:type limit,track by_src,count 1,seconds 60; http.method; content:"POST"; http.user_agent; content:"Mozilla/5.0 (Windows NT 6.1|3b 20|Trident/7.0|3b 20|rv|3a|10.0) like Gecko"; fast_pattern; depth:61; endswith; http.host; pcre:"/^\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3}/"; http.connection; content:"Close"; depth:5; endswith; http.protocol; content:"HTTP/1.1"; http.header_names; content:"|0d 0a|Host|0d 0a|"; depth:8; content:"Connection|0d 0a|"; distance:0; content:!"Referer|0d 0a|"; reference:md5,ac6ea1e500de772341a2075a7d916d63; classtype:trojan-activity; sid:2020064; rev:5; metadata:created_at 2014_12_23, signature_severity Major, tag Description_Generated_By_Proofpoint_Nexus, updated_at 2020_11_03;)