alert http $HOME_NET any -> $EXTERNAL_NET any (msg:"ET USER_AGENTS Suspicious User-Agent (QQ)"; flow:established,to_server; http.header_names; to_lowercase; content:!"|0d 0a|q-ua|0d 0a|"; http.user_agent; content:"QQ"; startswith; endswith; threshold:type limit,count 2,track by_src,seconds 300; classtype:trojan-activity; sid:2008199; rev:24; metadata:affected_product Any, attack_target Client_Endpoint, created_at 2010_07_30, deployment Perimeter, confidence High, signature_severity Major, tag User_Agent, updated_at 2024_05_04;)