Audit logon events&Logon type

Note

• In some cases, the reason for the logon failure may not be known.

Note

• This might occur as a result of the time limit on the security association expiring (the default is eight hours), policy changes, or peer termination.

Note

• This event is generated when a user is connected to a terminal server session over the network. It appears on the terminal server.

An event with logon type=2 occurs whenever a user logs on (or attempts to log on) a computer locally, e.g. by typing user name and password on Windows logon prompt. Events with logon type = 2 occur when a user logs on with a local or a domain account. However, if a user logs on with a domain account, this logon type will appear only when a user really authenticated in the domain (by a domain controller). In case if the DC not available, but the user provided valid domain credentials cached in the local PC, Windows will log an event with logon type = 11.

The description of this logon type clearly states that the event logged when somebody accesses a computer from the network. Commonly it appears when connecting to shared resources (shared folders, printers etc.). As we learned in the previous post, the connection with logon type = 3 could be established even from a local computer.

This event type appears when a scheduled task is about to be started. E.g. if you use Windows Task Scheduler and it’s time to start a task, Windows may create a new logon session to execute this task and register logon events (4648, 4624/4625). If a task is scheduled to run only when a “designated” user is logged on, a new logon session won’t be opened and logon events won’t be logged.

When Windows starts a service which is configured to log on as a user, Windows will create a new logon session for this service. This happens only if the service uses a “common” user account. If it uses special accounts, e.g. “Local System”, “NT AUTHORITY\LocalService” or “NT AUTHORITY\NetworkService”, Windows won’t create new logon sessions. The opened logon session will be closed when the service stops and a logoff event (4634) will be registered.

Note that event description doesn’t contain any information about the service name, process information lists only name of the service control manager (services.exe).  When Audit Failure logon event (4625) is registered with logon type = 5, this commonly means that the “designated” user has changed password, and you should update service logon details.

An event with logon type = 7 occurs when a user unlocks (or attempts to unlock) a previously locked workstation. Note that when a user unlocks computer, Windows creates a new logon session (or 2 logon sessions depending on the elevation conditions) and immediately closes it (with event 4634). When you are switching between logged on user accounts with Fast User Switching feature, you may think that such switching generates event 4624 with logon type = 7 because it looks like you lock and unlock workstation. However Windows generates events 4624 with logon type = 2 (interactive). When Audit Failure logon event (4625) is registered with logon type = 7, this commonly means that either you made a typo when entering the password, or someone is trying to break into the computer.

This event occurs when using RunAs command with /netonly option. Let’s say you need to run a program, but grant it extra permissions for network computers. E.g. you may want to run Event Log Explorer and give it additional permissions for a specific computer or a domain  (this may be helpful e.g. if you want to use a specific computer as a description server in Event Log Explorer, but your current permissions is not enough to access admin resources from this server). In this case you can run Event Log Explorer normally (using your current credentials), but specify special credentials for network connections. Let’s say your computer name is “WORK” and the description server name is “SERVER”. On WORK computer you type:

runas.exe /netonly /user:server\Administrator “c:\program files\event log explorer\elex.exe”

and provide administrator’s password when prompted.

This will run Event Log Explorer even if you provided a wrong password. This happens because it uses a cloned current credentials to run the program (a new logon session will be opened). And logon event 4624 will be logged with logon type = 9 (logoff event will be logged when you quit the application). But what about SERVER? The server will register 4624 or 4625 events in Security log with logon type = 3 but only when the application from WORK computer will try to access a shared resource on the server, e.g. Event Log Explorer will try to open resource file with event descriptions.

This logon type is similar to 2 (Interactive) but a user connects the computer from a remote machine via RDP (using Remote Desktop, Terminal Services or Remote Assistance).

When users logon a domain, Windows caches users’ credentials locally so that they can log on later even if a logon server (domain controller) is unavailable. By default Windows caches 10 or 25 last logon credentials (it depends on the operating system and can be increased up to 50). When a user attempts to logon with domain account while DC is not available, Windows checks the user’s credentials with these stored hashes and logs security events 4624 or 4625 with logon type = 11.