4801(S): The workstation was unlocked.

Subcategory: Audit Other Logon/Logoff Events

Event Description:

This event is generated when workstation was unlocked.

Note  For recommendations, see Security Monitoring Recommendations for this event.

Event XML:

- <Event xmlns="http://schemas.microsoft.com/win/2004/08/events/event">
- <System>
 <Provider Name="Microsoft-Windows-Security-Auditing" Guid="{54849625-5478-4994-A5BA-3E3B0328C30D}" /> 
 <EventID>4801</EventID> 
 <Version>0</Version> 
 <Level>0</Level> 
 <Task>12551</Task> 
 <Opcode>0</Opcode> 
 <Keywords>0x8020000000000000</Keywords> 
 <TimeCreated SystemTime="2015-09-10T23:47:05.886096400Z" /> 
 <EventRecordID>237657</EventRecordID> 
 <Correlation /> 
 <Execution ProcessID="504" ThreadID="4540" /> 
 <Channel>Security</Channel> 
 <Computer>DC01.contoso.local</Computer> 
 <Security /> 
 </System>
- <EventData>
 <Data Name="TargetUserSid">S-1-5-21-3457937927-2839227994-823803824-1104</Data> 
 <Data Name="TargetUserName">dadmin</Data> 
 <Data Name="TargetDomainName">CONTOSO</Data> 
 <Data Name="TargetLogonId">0x759a9</Data> 
 <Data Name="SessionId">3</Data> 
 </EventData>
 </Event>

Required Server Roles: None.

Minimum OS Version: Windows Server 2008, Windows Vista.

Event Versions: 0.

Field Descriptions:

Subject:

• Security ID [Type = SID]: SID of account that requested the “unlock workstation” operation. Event Viewer automatically tries to resolve SIDs and show the account name. If the SID cannot be resolved, you will see the source data in the event.

Note  A security identifier (SID) is a unique value of variable length used to identify a trustee (security principal). Each account has a unique SID that is issued by an authority, such as an Active Directory domain controller, and stored in a security database. Each time a user logs on, the system retrieves the SID for that user from the database and places it in the access token for that user. The system uses the SID in the access token to identify the user in all subsequent interactions with Windows security. When a SID has been used as the unique identifier for a user or group, it cannot ever be used again to identify another user or group. For more information about SIDs, see Security identifiers.

• Account Name [Type = UnicodeString]: the name of the account that requested the “unlock workstation” operation.

• Account Domain [Type = UnicodeString]: subject’s domain or computer name. Formats vary, and include the following:

  • Domain NETBIOS name example: CONTOSO

  • Lowercase full domain name: contoso.local

  • Uppercase full domain name: CONTOSO.LOCAL

  • For some well-known security principals, such as LOCAL SERVICE or ANONYMOUS LOGON, the value of this field is “NT AUTHORITY”.

  • For local user accounts, this field will contain the name of the computer or device that this account belongs to, for example: “Win81”.

• Logon ID [Type = HexInt64]: hexadecimal value that can help you correlate this event with recent events that might contain the same Logon ID, for example, “4624: An account was successfully logged on.”

• Session ID [Type = UInt32]: unique ID of unlocked session. You can see the list of current session IDs using “query session” command in command prompt. Example of output (see ID column):

Security Monitoring Recommendations

For 4801(S): The workstation was unlocked.

Important  For this event, also see Appendix A: Security monitoring recommendations for many audit events.

• Typically this is an informational event, and can give you information about when a machine was unlocked, and which account was used to unlock it.