ET POLICY Xpopup Instant Messenger Downloading Configuration

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;
)