alert tcp $EXTERNAL_NET any -> $HOME_NET 110 (msg:"GPL POP3 USER overflow attempt"; flow:to_server,established; content:"USER"; nocase; isdataat:50,relative; pcre:"/^USER\s[^\n]{50}/smi"; reference:bugtraq,11256; reference:bugtraq,789; reference:cve,1999-0494; reference:nessus,10311; classtype:attempted-admin; sid:2101866; rev:14; metadata:created_at 2010_09_23, confidence Medium, signature_severity Major, updated_at 2019_07_26;)