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4691(S): Indirect access to an object was requested.

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Event 4691 illustration

Subcategory: Audit Other Object Access Events

Event Description:

This event indicates that indirect access to an object was requested.

These events are generated for ALPC Ports access request actions.

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>4691</EventID> 
 <Version>0</Version> 
 <Level>0</Level> 
 <Task>12804</Task> 
 <Opcode>0</Opcode> 
 <Keywords>0x8020000000000000</Keywords> 
 <TimeCreated SystemTime="2015-09-23T01:03:49.834912100Z" /> 
 <EventRecordID>344382</EventRecordID> 
 <Correlation /> 
 <Execution ProcessID="4" ThreadID="2928" /> 
 <Channel>Security</Channel> 
 <Computer>DC01.contoso.local</Computer> 
 <Security /> 
 </System>
- <EventData>
 <Data Name="SubjectUserSid">S-1-5-21-3457937927-2839227994-823803824-1104</Data> 
 <Data Name="SubjectUserName">dadmin</Data> 
 <Data Name="SubjectDomainName">CONTOSO</Data> 
 <Data Name="SubjectLogonId">0x36509</Data> 
 <Data Name="ObjectType">ALPC Port</Data> 
 <Data Name="ObjectName">\\Sessions\\2\\Windows\\DwmApiPort</Data> 
 <Data Name="AccessList">%%4464</Data> 
 <Data Name="AccessMask">0x1</Data> 
 <Data Name="ProcessId">0xe60</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 an access to the object. 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 an access to the object.

  • 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.”

Object:

  • Object Type [Type = UnicodeString]: The type of an object for which access was requested.

    The following table contains the list of the most common Object Types:

Directory Event Timer Device
Mutant Type File Token
Thread Section WindowStation DebugObject
FilterCommunicationPort EventPair Driver IoCompletion
Controller SymbolicLink WmiGuid Process
Profile Desktop KeyedEvent Adapter
Key WaitablePort Callback Semaphore
Job Port FilterConnectionPort ALPC Port
  • Object Name [Type = UnicodeString]: full path and name of the object for which access was requested.

Process Information:

  • Process ID [Type = Pointer]: hexadecimal Process ID of the process through which the access was requested. Process ID (PID) is a number used by the operating system to uniquely identify an active process. To see the PID for a specific process you can, for example, use Task Manager (Details tab, PID column):

    Task manager illustration

    If you convert the hexadecimal value to decimal, you can compare it to the values in Task Manager.

    You can also correlate this process ID with a process ID in other events, for example, “4688: A new process has been created” Process Information\New Process ID.

Access Request Information:

  • Accesses [Type = UnicodeString]: the list of access rights which were requested by Subject\Security ID. These access rights depend on Object Type. Table of file access codes contains information about the most common access rights for file system objects. For information about ALPC ports access rights, use https://technet.microsoft.com/ or other informational resources.

  • Access Mask [Type = HexInt32]: hexadecimal mask for the operation that was requested or performed. For more information about file access rights, see Table of file access codes. For information about ALPC ports access rights, use https://technet.microsoft.com/ or other informational resources.

Security Monitoring Recommendations

For 4691(S): Indirect access to an object was requested.

  • Typically this event has little to no security relevance and is hard to parse or analyze. There is no recommendation for this event, unless you know exactly what you need to monitor with ALPC Ports.