alert http $HOME_NET any -> $EXTERNAL_NET any (msg:"ET MALWARE Kronos Checkin"; flow:established,to_server; http.method; content:"POST"; http.uri; content:"/upfornow/connect.php"; fast_pattern; http.header; content:"Content-Length|3a 20|"; http.header_names; content:!"Referer|0d 0a|"; reference:md5,f085395253a40ce8ca077228c2322010; reference:url,securityblog.s21sec.com/2014/08/kronos-is-here.html; classtype:command-and-control; sid:2018891; rev:4; metadata:created_at 2014_08_04, signature_severity Major, tag Description_Generated_By_Proofpoint_Nexus, updated_at 2020_09_25;)