alert http $HOME_NET any -> $EXTERNAL_NET any (msg:"ET POLICY Possible External IP Lookup ip.webmasterhome.cn"; flow:established,to_server; http.host; content:"ip.webmasterhome.cn"; fast_pattern; bsize:19; http.header_names; content:!"Referer|0d 0a|"; classtype:external-ip-check; sid:2021250; rev:6; metadata:attack_target Client_Endpoint, created_at 2015_06_11, deployment Perimeter, performance_impact Low, confidence High, signature_severity Informational, updated_at 2024_11_26, mitre_tactic_id TA0007, mitre_tactic_name Discovery, mitre_technique_id T1614, mitre_technique_name System_Location_Discovery;)