Method to calculate 'mechListMIC' for SPNEGO GSS-API(NTLMSSP_AUTH) accept-completed(0) state

Question

I am trying to learn and implement SMB2 Server. I am very interested to learn GSS-API (NTLMSSP, NTLMSSP_AUTH) inside. So, I am doing experiment with my own component of GSS-API. I read the description of mechListMIC in RFC4178 & RFC2478. But I couldn’t understand how to calculate mechListMIC for ‘SessionSetup Response, Unknown message type’ response.

Actually, I can generate the mechListMIC for negTokenInit phase of ‘NegotiateProtocol Response’. But the problem is, when client sends ‘SessionSetup Request, NTLMSSP_AUTH, User: Domain\Administrator, Unknown message type’ request, I can’t understand how is it generating ‘mechListMIC: 01 00 00 00 78 1E E9 4A DB 99 7F E9 00 00 00 00’ and how should I send response back in ‘SessionSetup Response, Unknown message type’ with corresponding mechListMIC based on the previous SessionSetup Request.

I tried with the following Info: SMB2.CSessionSetup.securityBlob.GSSAPI.InitialContextToken.InnerContextToken.SpnegoToken.NegTokenInit.MechTypes , hex data = 30 0C 06 0A 2B 06 01 04 01 82 37 02 02 0A

AND SMB2.CSessionSetup.securityBlob.GSSAPI.NegotiationToken.NegTokenResp.MechListMic, hex data = 01 00 00 00 78 1E E9 4A DB 99 7F E9 00 00 00 00

SecBuffer SignBuffers[2];

SignBufferDesc.ulVersion = SECBUFFER_VERSION; // SECBUFFER_VERSION = 0

SignBufferDesc.cBuffers = 2;

SignBufferDesc.pBuffers = SignBuffers;

SignBuffers[0] = 30 0C 06 0A 2B 06 01 04 01 82 37 02 02 0A;

SignBuffers[1] = 01 00 00 00 78 1E E9 4A DB 99 7F E9 00 00 00 00;

SignBuffers[0].BufferType = SECBUFFER_DATA; // SECBUFFER_DATA = 1

SignBuffers[1].BufferType = SECBUFFER_TOKEN; // SECBUFFER_TOKEN = 2

Can anyone please tell me what information do I need to use inside HMAC-MD5 (key, data) algorithm to generate mechListMIC for SessionSetup Response and how?

If it is possible to create a step-by-step example using my test case to calculate mechListMIC for ‘SessionSetup Response, Unknown message type’ response, that would be very helpful for me. Please let me know if you need any further information.

Thanks,
Shishir

Answer 1

Please find the answer in MSDN site http://social.msdn.microsoft.com/Forums/gu-IN/os_fileservices/thread/d00b4e1a-077b-4620-99c7-da7bf86d5212