Javamail NTLM Authentication Failure

Question

Trying to connect to Exchange server using NTLM in JavaMail. I can connect to SMTP, but not IMAP. I can also authenticate via the OS X Mail.app application using the ident

Answer 1

I had the same problem sending email via Exhange SMTP connector. After finding out that javamail does not support NTLMv2 authentication, I worked out a workaround that requires JCIFS library though.

I downloded the javamail api source code (https://java.net/projects/javamail/pages/Home) and edited the class com.sun.mail.auth.Ntlm to add the missing support for NTLMv2 using the JCIFS library support (http://jcifs.samba.org).

The first modification in file Ntlm.java was in method init0, and consisted of adding the missing flag NTLMSSP_NEGOTIATE_NTLM2:

private void init0() {
// ANDREA LUCIANO:
//    turn on the NTLMv2 negotiation flag in TYPE1 messages: 
//    NTLMSSP_NEGOTIATE_NTLM2   (0x00080000) 
//  See also http://davenport.sourceforge.net/ntlm.html#type1MessageExample

    type1 = new byte[256];
    type3 = new byte[256];
    System.arraycopy(new byte[] {'N','T','L','M','S','S','P',0,1}, 0,
            type1, 0, 9);
    type1[12] = (byte) 3;
    type1[13] = (byte) 0xb2;
    type1[14] = (byte) 0x08;  // ANDREA LUCIANO - added
// ...

The second modification was to replace the method generateType3Msg with this:

public String generateType3Msg(String challenge) {
    /* First decode the type2 message */
    byte[] type2 = null;
    try {
       type2 = BASE64DecoderStream.decode(challenge.getBytes("us-ascii"));
       logger.fine("type 2 message: " + toHex(type2)); // ANDREA LUCIANO - added
    } catch (UnsupportedEncodingException ex) {
       // should never happen
       assert false;
    }
    jcifs.ntlmssp.Type2Message t2m;
    try {
          t2m = new jcifs.ntlmssp.Type2Message(type2);
    } catch (IOException ex) {
          logger.log(Level.FINE, "Invalid Type 2 message", ex);
          return "";   // will fail later
    }

    final int type2Flags = t2m.getFlags();
    final int type3Flags = type2Flags & (0xffffffff ^ (jcifs.ntlmssp.NtlmFlags.NTLMSSP_TARGET_TYPE_DOMAIN | jcifs.ntlmssp.NtlmFlags.NTLMSSP_TARGET_TYPE_SERVER));

    jcifs.ntlmssp.Type3Message t3m = new jcifs.ntlmssp.Type3Message(t2m, password, ntdomain, username, hostname, type3Flags);
       return jcifs.util.Base64.encode(t3m.toByteArray());
}

The simpest way I found to patch the library is to compile the class and update the library jar file:

"c:\Program Files\Java\jdk1.5.0_22\bin\javac.exe" -cp jcifs-1.3.17.jar;javax.mail-1.5.2.jar -d . Ntlm.java 
 jar uvf javax.mail-1.5.2.jar com\sun\mail\auth\Ntlm.class

To enable debug as much as possible, I used the following code in the main method of my test class:

    final InputStream inputStream = Main.class.getResourceAsStream("/logging.properties");
    LogManager.getLogManager().readConfiguration(inputStream);

    Properties props = new Properties();

    props.put("mail.debug", "true");
    props.put("mail.debug.auth", "true");

with this logging.properties:

   # Logging
   handlers = java.util.logging.ConsoleHandler

  .level = INFO

  # Console Logging
  java.util.logging.ConsoleHandler.level = INFO

Before applying the patch the test was stuck after sending Type 1 message, because my Exchange server required NTLMv2 authentication. After the patch the athentication was done successfully.

Another solution is to send email via the ##Exchange webservice## aka EWS by using the ##EWS Java API## released and mantained by Microsoft (https://github.com/OfficeDev/ews-java-api), such as in this example:

public class Main {

/**
 * @param args
 */
public static void main(String[] args) throws Exception {

       ExchangeService exchangeService = new ExchangeService(ExchangeVersion.Exchange2007_SP1);

        ExchangeCredentials credentials = new WebCredentials("myusername","mypassword", "mydomain");

        exchangeService.setCredentials(credentials);
        exchangeService.setUrl(new URI("https://myhostname/EWS/Exchange.asmx"));

        exchangeService.setTraceEnabled(true);

        EmailMessage msg;
        msg = new EmailMessage(exchangeService);
        msg.setFrom(new EmailAddress("myuser@myserver.com"));
        msg.setSubject("Test Mail");
        msg.getToRecipients().add("myuser@gmail.com");
        msg.setBody(MessageBody.getMessageBodyFromText("Email sent by Miscrosoft Java EWS API."));
        msg.getAttachments().addFileAttachment("c:\\temp\\myattachement.pdf");
        msg.send();

}

}

But again there is a patch to apply in the inner class NTLM of EwsJCIFSNTLMScheme.java to enable NTLMv2 as indicated in the answer to this post:

How to use LDAP authentication for the Exchange Web Services connection in Java?

That is:

private class NTLM {
/** Character encoding */
public static final String DEFAULT_CHARSET = "ASCII";

/**
* The character was used by 3.x's NTLM to encode the username and
* password. Apparently, this is not needed in when passing username,
* password from NTCredentials to the JCIFS library
*/
private String credentialCharset = DEFAULT_CHARSET;

void setCredentialCharset(String credentialCharset) {
       this.credentialCharset = credentialCharset;
}

private static final int TYPE_1_FLAGS = NtlmFlags.NTLMSSP_NEGOTIATE_NTLM
             | NtlmFlags.NTLMSSP_NEGOTIATE_UNICODE
             | NtlmFlags.NTLMSSP_NEGOTIATE_NTLM2;

private String generateType1Msg(String host, String domain) {
       jcifs.ntlmssp.Type1Message t1m = new jcifs.ntlmssp.Type1Message(
                    TYPE_1_FLAGS, domain, host);
       return jcifs.util.Base64.encode(t1m.toByteArray());
}

private String generateType3Msg(String username, String password,
             String host, String domain, String challenge) {
       jcifs.ntlmssp.Type2Message t2m;
       try {
             t2m = new jcifs.ntlmssp.Type2Message(
                           jcifs.util.Base64.decode(challenge));
       } catch (IOException e) {
             throw new RuntimeException("Invalid Type2 message", e);
       }

       final int type2Flags = t2m.getFlags();
       final int type3Flags = type2Flags
                    & (0xffffffff ^ (NtlmFlags.NTLMSSP_TARGET_TYPE_DOMAIN | NtlmFlags.NTLMSSP_TARGET_TYPE_SERVER));

       jcifs.ntlmssp.Type3Message t3m = new jcifs.ntlmssp.Type3Message(
                    t2m, password, domain, username, host, type3Flags);
       return jcifs.util.Base64.encode(t3m.toByteArray());
}

}

I tried and it worked for me.