CloudFront 支援 JA3 資訊 (SSL/TLS fingerprint)

看到 CloudFront 宣佈支援帶入 JA3 資訊了:「Amazon CloudFront now supports JA3 fingerprint headers」:

Details: Amazon CloudFront now supports Cloudfront-viewer-ja3-fingerprint headers, enabling customers to access incoming viewer requests’ JA3 fingerprints. Customers can use the JA3 fingerprints to implement custom logic to block malicious clients or allow requests from expected clients only.

JA3 的頁面上可以看到說明,針對 SSL/TLS 這個複雜的 handshake 過程中,就可以從中得知不同的 client 實做,比起容易偽造的 User-agent 有效:

JA3 is a method for creating SSL/TLS client fingerprints that should be easy to produce on any platform and can be easily shared for threat intelligence.

像是 Tor 的 SSL/TLS 連線就會有對應的 fingerprint 可以偵測:

JA3 fingerprint for the standard Tor client:

先前在「修正 Curl 的 TLS handshake,避開 bot 偵測機制」裡面提到的 curl-impersonate 就是反制這類偵測的方式。