How to Find Logon Failure Reason for Logon Type 3
This logon type occurs due to accessing a computer from elsewhere on the network (i.e Remote Desktop sharing tool), or accessing other resources like Network Share from elsewhere on the network by passing credentials. One of the most common sources of logon events with Logon type 3 is connections to shared folders or printers. But also other over-the-network logons are classed as logon type 3 as well as most logons to IIS except Basic authentication.
Consider following scenario:
DC1 - Active Directory Domain Controller Morgan-PC - End user desktop computer
Now, when a user or any other applications tries to access resources like Network Share from Morgan-PC with wrong credentials, we will get the logon failure event 4625 with logon type 3 in DC1 and it will points the machine Morgan-PC as Source Machine.
Event 4625 for Logon Type 3:
Computer: DC1.TestDomain.Com Description: An account failed to log on. Logon Type: 3 Account For Which Logon Failed: Account Name: Morgan Account Domain: TESTDOMAIN Failure Information: Failure Reason: Unknown user name or bad password. Status: 0xc000006d Sub Status: 0xc000006a Network Information: Workstation Name: Morgan-PC Source Network Address: 212.158.1.110 Source Port: 51283
Consider another scenario:
DC1 - Active Directory Domain Controller Morgan-PC - End user desktop computer
Now, when a user tries to login into DC1 from Morgan-PC via Remote Desktop sharing tool with bad password, we will get the logon failure event 4625 with logon type 3 in DC1 and it will points the machine Morgan-PC as Source Machine.