Impersonating a thread using GSSAPI's established security context, on Windows - winapi

I am working on enabling Kerberos authentication/delegation in my application.
My setup: The client is any web browser. The server runs on Windows and hosts some of my services, with Apache/Tomcat as the front end. The server can delegate work to one or more of my services on one or more machines. My services run in Java, but invoke C++ code via JNI and the C++ code makes the connection to the data sources (via ODBC for most relational data sources). Currently I am working on connecting to SQL Server via its ODBC driver.
I have mod_auth_kerb set up in Apache, and that is able to authenticate the user using Kerberos. My question: How do I use the established security context to impersonate the thread which will invoke the ODBC driver's SQLDriverConnect call? I have a working prototype that uses LogonUser and ImpersonateLoggedonUser API's to login a particular user (using her username and password) and impersonate her on the thread that invokes the SQLDriverConnect call on the SQL Server ODBC driver. But I don't know how to use GSSAPI's established security context/delegated context (gss_ctx_id_t/gss_cred_id_t) to impersonate my thread. In other words, how do I convert the GSSAPI's handles into SSPI handles so that I can invoke ImpersonateSecurityContext or ImpersonateLoggedonUser or similar Win32 API's.
Any help would be appreciated. Thanks!
Ed

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I need to ensure that Service accepts connections from my Application only, and it is not altered.
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Using logged in identity for seamless authentication with service using LDAP authentication

Let's assume we can not get password of the current user, only username and domain if necessary. Is it possible to get a session token or something similar to authenticate with remote service using LDAP authentication?
UPDATE
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In ASP.NET, the implementation also depends on if you're using the .NET Framework or .NET Core.
To give you any more information, you will need to specify what type of application you're working on and on which OS.

How to sniff Oracle's credentials from a connection attempt to the database?

I have a legacy application, which connects to the configured Oracle database.
It seems it has some logic that alters the database credentials as it is unable to successfully log in to the Oracle database, while sqlplus started on the same machine is able to log in.
The error I am getting is: [DataDirect][ODBC Oracle Wire Protocol driver][Oracle]ORA-01017: invalid username/password; logon denied
How to find out what is the database username and password that are sent to the database?
What I have tried so far:
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Used a sniffer to eavesdrop the network traffic between the machine running the application and the database, but since Oracle's TNS protocol is encrypted, it did not help a lot.
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Enabled tracing of the JDBC driver (Trace=1, TraceFile, TraceDll). The trace file shows the correct username, but obviously the password is not getting logged.
My environment:
Database: Oracle 11g
Application runs on: Solaris
Application uses: DataDirect ODBC Oracle Wire Protocol v70
I not sure, but if connection established by ODBC driver (as described in question tags) then you can try ODBC sniffing tools like ODBC Tracing.
Citation:
Password "Sniffing" Using Trace
ODBC provides a means for tracing the conversation taking place between the driver and the host database. Used by developers for testing purposes, the tracing feature is designed to help programmers find out exactly what is going on and to help fix problems. However, tracing (also called "sniffing") can be used by nefarious bad guys to retrieve user passwords.
When tracing is enabled, communications with the host are written to a file. This includes the user ID and password, which are captured in plain text.
Update
SQLPlus connects to Oracle with OCI interface, but DataDirect ODBC driver uses it's own proprietary implementation of communication protocol. So, most probable point of failure is driver misconfiguration or incompatibility.
DataDirect provides some tools for ODBC drivers diagnostics, but only option applicable to case described in question is using snoop utility, which acts like a netcat which already tried.
Because connection failed at credential verification stage, the most probable source of error is using localized symbols for user name or password. There are some issues with Oracle authentication process, listed in DataDirect Knowledge Search (search for ORA-01017).
It seems that DataDirect provides two separate version of driver with and without Unicode support, therefore one of possible points of failure is to connecting with non-Unicode version of driver to Unicode version of database and vice verse.
P.S. For now I don't have any experience with DataDirect ODBC driver. So it's only suggestions about possible source of failure.

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I'm trying to extend a windows service I've written to accept a kerberos ticket from a client and then delegate that ticket to an ODBC driver so it can connect to another server with it.
The ODBC driver works with kerberos authentication fine in a standalone scenario. That is, it can request and forward on a ticket for the current user just fine. But in my service, I may be dealing with multiple users at once. How do I accept a ticket so that when I connect to the ODBC driver it discovers and uses the correct user's ticket?
One possibility I can think of is to create a new process as the desired user by using the ticket. However, I would really like to avoid this if possible as it does not fit well within the current architecture of my service.
(Note: My service is written in C/C++ with the Win32 api)
I found the answer to my own question.
After authenticating a security context, I can use the ImpersonateSecurityContext function. This will cause the current thread to run as client who initiated the security context. From that thread I can call the connection functions for the ODBC driver and it will authenticate as the correct user.
http://msdn.microsoft.com/en-us/library/aa375497%28v=vs.85%29.aspx

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