ET MALWARE Ursnif Variant CnC Beacon 4

alert http $HOME_NET any -> $EXTERNAL_NET any (
    msg:"ET MALWARE Ursnif Variant CnC Beacon 4";
    flow:established,to_server;
    urilen:>125;
    http.method;
    content:"GET";
    http.uri;
    content:".";
    pcre:"/\.(?:gif|bmp|jpeg|png)$/";
    http.user_agent; bsize:50;
    content:"Mozilla/4.0 (compatible|3b 20|MSIE 8.0|3b 20|Windows NT 6.1)"; fast_pattern;
    http.connection; bsize:10;
    content:"Keep-Alive";
    http.header_names;
    content:!"|0d 0a|Accept";
    content:!"|0d 0a|Referer|0d 0a|";
    content:"|0d 0a|User-Agent|0d 0a|Host|0d 0a|";
    content:"|0d 0a|Connection|0d 0a|"; distance:0;
    pcre:"/\x0d\x0aUser-Agent\x0d\x0aHost\x0d\x0a(?:Content-Length\x0d\x0a)?Connection\x0d\x0a(?:Cache-Control|Pragma)\x0d\x0a\x0d\x0a$/";
    reference:md5,f870c0d62691fc39194922e4a59fdc1c;
    classtype:command-and-control;
    sid:2021829; rev:6;
    metadata:attack_target Client_Endpoint, created_at 2015_09_24, deployment Perimeter, signature_severity Major, tag c2, updated_at 2024_03_12, mitre_tactic_id TA0010, mitre_tactic_name Exfiltration, mitre_technique_id T1041, mitre_technique_name Exfiltration_Over_C2_Channel;
)