C# Signature:

[DllImport("secur32.dll", SetLastError = false)]

private static extern uint LsaFreeReturnBuffer(IntPtr buffer);

[DllImport("Secur32.dll", SetLastError = false)]

private static extern uint LsaEnumerateLogonSessions(out UInt64 LogonSessionCount, out IntPtr LogonSessionList);

[DllImport("Secur32.dll", SetLastError = false)]

private static extern uint LsaGetLogonSessionData(IntPtr luid, out IntPtr ppLogonSessionData);

[StructLayout(LayoutKind.Sequential)]

private struct LSA_UNICODE_STRING

{

    public UInt16 Length;
    public UInt16 MaximumLength;
    public IntPtr buffer;

}

[StructLayout(LayoutKind.Sequential)]

private struct LUID

{

    public UInt32 LowPart;
    public UInt32 HighPart;

}

[StructLayout(LayoutKind.Sequential)]

private struct SECURITY_LOGON_SESSION_DATA

{

    public UInt32 Size;
    public LUID LoginID;
    public LSA_UNICODE_STRING Username;
    public LSA_UNICODE_STRING LoginDomain;
    public LSA_UNICODE_STRING AuthenticationPackage;
    public UInt32 LogonType;
    public UInt32 Session;
    public IntPtr PSiD;
    public UInt64 LoginTime;
    public LSA_UNICODE_STRING LogonServer;
    public LSA_UNICODE_STRING DnsDomainName;
    public LSA_UNICODE_STRING Upn;

}

private enum SECURITY_LOGON_TYPE : uint

{

    Interactive = 2,    //The security principal is logging on interactively.
    Network,        //The security principal is logging using a network.
    Batch,          //The logon is for a batch process.
    Service,        //The logon is for a service account.
    Proxy,          //Not supported.
    Unlock,         //The logon is an attempt to unlock a workstation.
    NetworkCleartext,   //The logon is a network logon with cleartext credentials.
    NewCredentials,     // Allows the caller to clone its current token and specify new credentials for outbound connections.
    RemoteInteractive,  // A terminal server session that is both remote and interactive.
    CachedInteractive,  // Attempt to use the cached credentials without going out across the network.
    CachedRemoteInteractive, // Same as RemoteInteractive, except used internally for auditing purposes.
    CachedUnlock      // The logon is an attempt to unlock a workstation.

}

VB Signature:

Declare Function LsaGetLogonSessionData Lib "secur32.dll" (TODO) As TODO

User-Defined Types:

None.

Alternative Managed API:

Do you know one? Please contribute it!

Notes:

None.

Tips & Tricks:

Please add some!

Sample Code:

DateTime systime = new DateTime(1601, 1, 1, 0, 0, 0, 0); //win32 systemdate

  UInt64 count;
  IntPtr luidPtr = IntPtr.Zero;
  LsaEnumerateLogonSessions(out count, out luidPtr);  //gets an array of pointers to LUIDs

  IntPtr iter = luidPtr;      //set the pointer to the start of the array

  for (ulong i = 0; i < count; i++)   //for each pointer in the array
  {
      IntPtr sessionData;

      LsaGetLogonSessionData(iter, out sessionData);
      SECURITY_LOGON_SESSION_DATA data = (SECURITY_LOGON_SESSION_DATA)Marshal.PtrToStructure(sessionData, typeof(SECURITY_LOGON_SESSION_DATA));

      //if we have a valid logon
      if (data.PSiD != IntPtr.Zero)
      {
      //get the security identifier for further use
      System.Security.Principal.SecurityIdentifier sid = new System.Security.Principal.SecurityIdentifier(data.PSiD);

      //extract some useful information from the session data struct
      string username = Marshal.PtrToStringUni(data.Username.buffer).Trim();      //get the account username
      string domain =  Marshal.PtrToStringUni(data.LoginDomain.buffer).Trim();    //domain for this account  
      string authpackage = Marshal.PtrToStringUni(data.AuthenticationPackage.buffer).Trim();    //authentication package

      SECURITY_LOGON_TYPE secType = (SECURITY_LOGON_TYPE)data.LogonType;
      DateTime time = systime.AddTicks((long)data.LoginTime);                  //get the datetime the session was logged in

      //do something with the extracted data, ie, add to a display control....
      listBox1.Items.Add("User: " + username + " *** Domain: " + domain + " *** Login Type: (" + data.LogonType + ") " + secType.ToString() +" *** Login Time: "+time.ToLocalTime().ToString());

      }
      iter = (IntPtr)((int)iter + Marshal.SizeOf(typeof(LUID)));  //move the pointer forward
      LsaFreeReturnBuffer(sessionData);   //free the SECURITY_LOGON_SESSION_DATA memory in the struct
  }
  LsaFreeReturnBuffer(luidPtr);   //free the array of LUIDs

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