ET PHISHING Request for Possible Common Brand Phishing Hosted on Legitimate Windows Service

alert tls $HOME_NET any -> $EXTERNAL_NET any (
    msg:"ET PHISHING Request for Possible Common Brand Phishing Hosted on Legitimate Windows Service";
    flow:established,to_server;
    tls.sni;
    content:".core.windows.net"; endswith;
    pcre:"/^(?:d(?:(?:ocu|uco)sign|ropbox)|o(?:ffice365|nedrive)|adobe|gdoc)/";
    pcre:!"/^onedrivecl[a-z]{2}prod[a-z]{2}[0-9]{5}\./";
    classtype:policy-violation;
    sid:2026487; rev:12;
    metadata:affected_product Web_Browsers, attack_target Client_Endpoint, created_at 2018_10_15, deployment Perimeter, confidence Medium, signature_severity Minor, tag Phishing, updated_at 2020_11_17;
)