fix feat TrustManager that accepts all certificates

[odaysec]

java/kubernetes/src/main/java/io/kubernetes/client/openapi/ApiClient.java

Lines 1499 to 1520 in c14bb93

	trustManagers = new TrustManager[]{
	new X509TrustManager() {
	@Override
	public void checkClientTrusted(java.security.cert.X509Certificate[] chain, String authType) throws CertificateException {
	}
	@Override
	public void checkServerTrusted(java.security.cert.X509Certificate[] chain, String authType) throws CertificateException {
	}
	@Override
	public java.security.cert.X509Certificate[] getAcceptedIssuers() {
	return new java.security.cert.X509Certificate[]{};
	}
	}
	};
	hostnameVerifier = new HostnameVerifier() {
	@Override
	public boolean verify(String hostname, SSLSession session) {
	return true;
	}
	};

To address this vulnerability, we must remove the custom TrustManager and HostnameVerifier that accept all certificates.

• If the intention is to allow self-signed certificates in some cases, explicit trusted certificates should be loaded from a secure location into a KeyStore, as demonstrated in the good example in the background.
• The TrustManager should be initialized via a TrustManagerFactory with a KeyStore containing only the explicitly trusted certificates.
• Hostname verification should not be disabled; use the standard verifier unless on localhost for very specific reasons.
• Changes are required within the applySslSettings() method:
  • Remove (or replace) the block starting on line 1498 that creates an insecure TrustManager and HostnameVerifier.
  • Instead, if verifyingSsl is false, throw an exception or require the user to provide a trusted CA cert, as in the else branch. This eliminates the insecure option entirely.

References

Security with HTTPS and SSL

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