alert tcp $HOME_NET any -> $EXTERNAL_NET 25 (msg:"ET MALWARE Linux.Mumblehard Spam Command CnC"; flow:to_server,established; content:"POST / HTTP/1."; depth:14; content:"|0d 0a 0d 0a 0f 0f|"; pcre:"/^\d{1,3}[0-2]/R"; reference:url,www.welivesecurity.com/wp-content/uploads/2015/04/mumblehard.pdf; reference:md5,86f0b0b74fe8b95b163a1b31d76f7917; classtype:command-and-control; sid:2021053; rev:1; metadata:created_at 2015_05_04, confidence Medium, signature_severity Major, tag Description_Generated_By_Proofpoint_Nexus, updated_at 2019_07_26;)