alert http $HOME_NET any -> $EXTERNAL_NET any (msg:"ET POLICY Xpopup Instant Messenger Downloading Configuration"; flow:established,to_server; urilen:13; http.method; content:"GET"; http.uri; content:"/xpopinfo.dat"; fast_pattern; http.user_agent; content:"Mozilla/4.1 (compatible|3b 20|"; startswith; http.header_names; content:!"Referer|0d 0a|"; reference:md5,6c7abe2297ee64362e33584f9f654ebd; classtype:policy-violation; sid:2021205; rev:5; metadata:created_at 2015_06_09, confidence High, signature_severity Informational, updated_at 2020_05_22;)