Adding User Name to Events

Introduction

This article will explain how to add a user name to the Events that are logged in to the Event Viewer.

Background

I needed to add user names to events that were being logged, and I could not find anything directly on target. Microsoft's website stated to simply add the SID to the ReportEvent function. It did not tell how to get the SID. After much more investigation, I found something written in another programming language that got the user SID, so I translated it into C and combined it with what I was doing.

Using the code

I wrote a standalone program first to test out what I wanted to do at work. I will provide all the relevant portions here so that you can simply paste into your project something that works.

    HANDLE hToken;
    HANDLE g_eventHandle = NULL;
    int rc;
    DWORD dwLength = 0;
    PTOKEN_USER pTokenUser = NULL;
    TCHAR *params[1];

        // in order to use ReportEvent we must first Register Event
    g_eventHandle = RegisterEventSource(NULL, _T("SID_TEST"));
    OpenProcessToken(GetCurrentProcess(), TOKEN_QUERY, &hToken);

    // Get required buffer size and allocate the PTOKEN_USER buffer.
    if (!GetTokenInformation(
        hToken,         // handle to the access token
        TokenUser,    // get information about the token's groups
        (LPVOID) pTokenUser,   // pointer to TOKEN_USER buffer
        0,              // size of buffer
        &dwLength       // receives required buffer size
    ))
    {
        if (GetLastError() != ERROR_INSUFFICIENT_BUFFER)
            goto Cleanup;

        pTokenUser = (PTOKEN_USER)HeapAlloc(GetProcessHeap(),
            HEAP_ZERO_MEMORY, dwLength);

        if (pTokenUser == NULL)
            goto Cleanup;
    }

    // Get the token group information from the access token.
    if (!GetTokenInformation(
        hToken,         // handle to the access token
        TokenUser,    // get information about the token's groups
        (LPVOID) pTokenUser,   // pointer to TOKEN_USER buffer
        dwLength,       // size of buffer
        &dwLength       // receives required buffer size
    ))
    {
        goto Cleanup;
    }

    params[0] = const_cast<TCHAR*>("test string");

    // the actual call that places the event into the Event Viewer
    rc = ReportEvent(g_eventHandle, EVENTLOG_INFORMATION_TYPE, 0, 0,
        pTokenUser->User.Sid,// the sid goes here <-------
        1, 0, (LPCTSTR *)params, NULL);

Cleanup:

    // Free the buffer for the token .
    if (pTokenUser != NULL)
        HeapFree(GetProcessHeap(), 0, (LPVOID)pTokenUser);

    // i am finished with the Event
    DeregisterEventSource(g_eventHandle);

Points of Interest

That's all there is to it. The GetTokenInformation function has to be called twice; if you have too much or too little allocated for your SID, the function will fail.

The Event View with our entry: