ET HUNTING Minimal Header Github Request for PNG File

alert http $HOME_NET any -> $EXTERNAL_NET any (
    msg:"ET HUNTING Minimal Header Github Request for PNG File";
    flow:established,to_server;
    http.method;
    content:"GET";
    http.uri;
    content:".png"; endswith;
    http.host;
    content:"github.com"; endswith; fast_pattern;
    http.connection;
    content:"Keep-Alive";
    http.header_names; bsize:<30;
    content:!"|0d 0a|user-agent|0d 0a|"; nocase;
    content:!"|0d 0a|referer|0d 0a|"; nocase;
    content:!"|0d 0a|accept|0d 0a|"; nocase;
    content:!"|0d 0a|x-auth|0d 0a|"; nocase;
    content:!"|0d 0a|cookie|0d 0a|"; nocase;
    reference:md5,bedd7b113e7db2fc8fb91c74089b9c27;
    classtype:misc-activity;
    sid:2064697; rev:1;
    metadata:affected_product Windows_XP_Vista_7_8_10_Server_32_64_Bit, affected_product Mac_OSX, affected_product Linux, attack_target Client_Endpoint, tls_state TLSDecrypt, created_at 2025_09_15, deployment Perimeter, deployment SSLDecrypt, performance_impact Significant, confidence Medium, signature_severity Informational, tag Description_Generated_By_Proofpoint_Nexus, updated_at 2025_09_15;
    target:src_ip;
)