To prevent URL spoofing, ``++HostnameVerifier.verify()++`` methods should do more than simply ``++return true++``. Doing so may get you quickly past an exception, but that comes at the cost of opening a security hole in your application. 

== Noncompliant Code Example

----
SSLContext sslcontext = SSLContext.getInstance( "TLS" );
sslcontext.init(null, new TrustManager[]{new X509TrustManager() {
  public void checkClientTrusted(X509Certificate[] arg0, String arg1) throws CertificateException {}
  public void checkServerTrusted(X509Certificate[] arg0, String arg1) throws CertificateException {}
  public X509Certificate[] getAcceptedIssuers() { return new X509Certificate[0]; }

}}, new java.security.SecureRandom());

Client client = ClientBuilder.newBuilder().sslContext(sslcontext).hostnameVerifier(new HostnameVerifier() {
  @Override
  public boolean verify(String requestedHost, SSLSession remoteServerSession) {
    return true;  // Noncompliant
  }
}).build();
----

== Compliant Solution

----
SSLContext sslcontext = SSLContext.getInstance( "TLSv1.2" );
sslcontext.init(null, new TrustManager[]{new X509TrustManager() {
  @Override
  public void checkClientTrusted(X509Certificate[] arg0, String arg1) throws CertificateException {}
  @Override
  public void checkServerTrusted(X509Certificate[] arg0, String arg1) throws CertificateException {}
  @Override
  public X509Certificate[] getAcceptedIssuers() { return new X509Certificate[0]; }

}}, new java.security.SecureRandom());

Client client = ClientBuilder.newBuilder().sslContext(sslcontext).hostnameVerifier(new HostnameVerifier() {
  @Override
  public boolean verify(String requestedHost, SSLSession remoteServerSession) {
    return requestedHost.equalsIgnoreCase(remoteServerSession.getPeerHost()); // Compliant
  }
}).build();
----

== See

* https://www.owasp.org/index.php/Top_10-2017_A6-Security_Misconfiguration[OWASP Top 10 2017 Category A6] - Security Misconfiguration
* http://cwe.mitre.org/data/definitions/295.html[MITRE, CWE-295] - Improper Certificate Validation
* Derived from FindSecBugs rule https://find-sec-bugs.github.io/bugs.htm#WEAK_HOSTNAME_VERIFIER[WEAK_HOSTNAME_VERIFIER]