Got a bit of a strange one I'm hoping somebody can explain.
To set the scene:
- These are standard users
- They don't have local admin on any machines
- They don't have any special domain membership or rights
- The DC is the fileserver, there are 2 and we see these logs on both.
- The general aim here is to be able to audit all none system Elevated Tokens as suspicous.
I am seeing the below Event on our domain controllers for users who do not have admin rights and therefore (as far I can tell) shouldn't be getting elevated tokens. When looking on the local machine I am not seeing any elevated token logins but I am usually (perhaps always, can't say for certain) seeing a new process creation, the process varies, so far I've seen Chrome and C:\Windows\System32\taskhostw.exe. I think I have also seen it correlate to gpupdate running.
My questions are:
- Why would a new process that seems local to the machine in question kickoff a network authentication?
- I can think of a number of reasons I suppose but it doesn't seem strictly necessary.
- Why would those processes network connections request an elevated token?
- How are they being granted an elevated token when all the docs say they shouldn't?
- Why/how is the new process being started as the user able to get a Type 1 token.
Relevant details below but let me know if you want more:
Event 4625 from DC
An account was successfully logged on.
Subject:
Security ID: S-1-0-0
Account Name: -
Account Domain: -
Logon ID: 0x0
Logon Information:
Logon Type: 3
Restricted Admin Mode: -
Virtual Account: No
Elevated Token: Yes
Impersonation Level: Delegation
New Logon:
Security ID: S-1-5-21-2694983979-2918899769-1333944616-3622
Account Name: TestUser
Account Domain: LAN.CONTOSO.COM
Logon ID: 0xCE02D4F1
Linked Logon ID: 0x0
Network Account Name: -
Network Account Domain: -
Logon GUID: {1FB466DC-C6B8-19AD-313B-F65024F43969}
Process Information:
Process ID: 0x0
Process Name: -
Network Information:
Workstation Name: -
Source Network Address: 192.168.2.5
Source Port: 54805
Detailed Authentication Information:
Logon Process: Kerberos
Authentication Package: Kerberos
Transited Services: -
Package Name (NTLM only): -
Key Length: 0
This event is generated when a logon session is created. It is generated on the computer that was accessed.
The subject fields indicate the account on the local system which requested the logon. This is most commonly a service such as the Server service, or a local process such as Winlogon.exe or Services.exe.
The logon type field indicates the kind of logon that occurred. The most common types are 2 (interactive) and 3 (network).
The New Logon fields indicate the account for whom the new logon was created, i.e. the account that was logged on.
The network fields indicate where a remote logon request originated. Workstation name is not always available and may be left blank in some cases.
The impersonation level field indicates the extent to which a process in the logon session can impersonate.
The authentication information fields provide detailed information about this specific logon request.
- Logon GUID is a unique identifier that can be used to correlate this event with a KDC event.
- Transited services indicate which intermediate services have participated in this logon request.
- Package name indicates which sub-protocol was used among the NTLM protocols.
- Key length indicates the length of the generated session key. This will be 0 if no session key was requested.
Event 4688 from Client
On Token Elevation Type: %%1936 = Type 1 Full Token
A new process has been created.
Creator Subject:
Security ID: S-1-5-18
Account Name: UK-LAPTOP-004$
Account Domain: CONTOSO
Logon ID: 0x3E7
Target Subject:
Security ID: S-1-5-21-2694983979-2918899769-1333944616-3622
Account Name: TestUser
Account Domain: CONTOSO
Logon ID: 0x7237F8F0
Process Information:
New Process ID: 0x502c
New Process Name: C:\Windows\System32\taskhostw.exe
Token Elevation Type: %%1936 - Type 1 Full Token
Mandatory Label: S-1-16-8192
Creator Process ID: 0xbf8
Creator Process Name: C:\Windows\System32\svchost.exe
Process Command Line:
Token Elevation Type indicates the type of token that was assigned to the new process in accordance with User Account Control policy.
Type 1 is a full token with no privileges removed or groups disabled. A full token is only used if User Account Control is disabled or if the user is the built-in Administrator account or a service account.
Type 2 is an elevated token with no privileges removed or groups disabled. An elevated token is used when User Account Control is enabled and the user chooses to start the program using Run as administrator. An elevated token is also used when an application is configured to always require administrative privilege or to always require maximum privilege, and the user is a member of the Administrators group.
Type 3 is a limited token with administrative privileges removed and administrative groups disabled. The limited token is used when User Account Control is enabled, the application does not require administrative privilege, and the user does not choose to start the program using Run as administrator.
Sources
4624: https://docs.microsoft.com/en-us/windows/security/threat-protection/auditing/event-4624
4688: https://docs.microsoft.com/en-us/windows/security/threat-protection/auditing/event-4688
