ET INFO Observed Usage of Non-Alphanumeric Javascript Obfuscation M2

alert http $EXTERNAL_NET any -> $HOME_NET any (
    msg:"ET INFO Observed Usage of Non-Alphanumeric Javascript Obfuscation M2";
    flow:established,to_client;
    http.stat_code;
    content:"200";
    http.response_body;
    content:"$=String.fromCharCode("; fast_pattern;
    content:"+";
    pcre:"/^(?:\x5b\x5d[^a-zA-Z0-9]+?){5,10}/R";
    reference:url,businessinfo.co.uk/labs/talk/Nonalpha.pdf;
    reference:url,github.com/cilame/unjsfuck;
    reference:url,unit42.paloaltonetworks.com/malicious-javascript-using-jsfiretruck-as-obfuscation/;
    reference:url,jsfuck.com/;
    reference:url,github.com/aemkei/jsfuck;
    classtype:misc-activity;
    sid:2063161; rev:4;
    metadata:attack_target Client_Endpoint, tls_state TLSDecrypt, created_at 2025_06_23, deployment Perimeter, deployment SSLDecrypt, performance_impact Low, confidence High, signature_severity Informational, tag JavaScript, updated_at 2025_06_25;
)