ET HUNTING Base64 Encoded 2 byte ROL Windows OS Name in HTTP Header

alert http $HOME_NET any -> $EXTERNAL_NET any (
    msg:"ET HUNTING Base64 Encoded 2 byte ROL Windows OS Name in HTTP Header";
    flow:established,to_server;
    http.header;
    content:"XaW5kb3dz"; fast_pattern;
    pcre:"/^Q?(?:YDE(w|x)A)?\x3d{2}/R";
    threshold:type limit,count 1,seconds 300,track by_src;
    reference:md5,f5ef5f40922113c2dfb32c202ae2b3f5;
    classtype:misc-activity;
    sid:2067864; rev:1;
    metadata:affected_product Windows_XP_Vista_7_8_10_Server_32_64_Bit, attack_target Client_Endpoint, tls_state TLSDecrypt, created_at 2026_02_20, deployment Perimeter, deployment SSLDecrypt, confidence High, signature_severity Informational, updated_at 2026_02_20, mitre_tactic_id TA0005, mitre_tactic_name Defense_Evasion, mitre_technique_id T1027, mitre_technique_name Obfuscated_Files_or_Information;
    target:src_ip;
)