alert http $HOME_NET any -> $EXTERNAL_NET any (msg:"ET MALWARE Sefnit Checkin"; flow:established,to_server; http.uri; content:"/0001"; fast_pattern; pcre:"/^\/j\/[a-f0-9]{8}[\x2d\x5f]?[a-f0-9]{4}[\x2d\x5f]?[a-f0-9]{4}[\x2d\x5f]?[a-f0-9]{4}[\x2d\x5f]?[a-f0-9]{12}\/0001\/?$/"; reference:url,www.facebook.com/notes/protect-the-graph/sefnit-is-back/1448087102098103; classtype:command-and-control; sid:2018448; rev:5; metadata:created_at 2014_05_05, signature_severity Major, updated_at 2020_09_24;)