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42 lines
2.9 KiB
Markdown
42 lines
2.9 KiB
Markdown
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# Unconstrained Delegation
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## Unconstrained delegation
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This a feature that a Domain Administrator can set to any **Computer** inside the domain. Then, anytime a **user logins** onto the Computer, a **copy of the TGT** of that user is going to be **sent inside the TGS** provided by the DC **and saved in memory in LSASS**. So, if you have Administrator privileges on the machine, you will be able to **dump the tickets and impersonate the users** on any machine.
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So if a domain admin logins inside a Computer with "Unconstrained Delegation" feature activated, and you have local admin privileges inside that machine, you will be able to dump the ticket and impersonate the Domain Admin anywhere \(domain privesc\).
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You can **find Computer objects with this attribute** checking if the [userAccountControl](https://msdn.microsoft.com/en-us/library/ms680832%28v=vs.85%29.aspx) attribute contains [ADS\_UF\_TRUSTED\_FOR\_DELEGATION](https://msdn.microsoft.com/en-us/library/aa772300%28v=vs.85%29.aspx). You can do this with an LDAP filter of ‘\(userAccountControl:1.2.840.113556.1.4.803:=524288\)’, which is what powerview does:
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```bash
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Get-NetComputer -Unconstrained #DCs always appear but aren't useful for privesc
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#Export tickets with Mimikatz
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privilege::debug
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sekurlsa::tickets /export #Recommended way
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kerberos::list /export #Another way
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```
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Load the ticket of Administrator \(or victim user\) in memory with **Mimikatz** or **Rubeus for a** [**Pass the Ticket**](pass-the-ticket.md)**.**
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More info: [https://www.harmj0y.net/blog/activedirectory/s4u2pwnage/](https://www.harmj0y.net/blog/activedirectory/s4u2pwnage/)
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[**More information about Unconstrained delegation in ired.team.**](https://ired.team/offensive-security-experiments/active-directory-kerberos-abuse/domain-compromise-via-unrestricted-kerberos-delegation)\*\*\*\*
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### **Automatically compromising a Print server**
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If an attacker is able to **compromise a computer allowed for "Unconstrained Delegation"**, he could **trick** a **Print server** to **automatically login** against it **saving a TGT** in the memory of the server.
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Then, the attacker could perform a **Pass the Ticket attack to impersonate** the user Print server computer account.
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To make a print server login against any machine you can use [**SpoolSample**](https://github.com/leechristensen/SpoolSample):
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```bash
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.\SpoolSample.exe printmachine unconstrinedmachine
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```
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If the TGT if from a domain controller, you could perform a[ **DCSync attack**](acl-persistence-abuse.md#dcsync) and obtain all the hashes from the DC.
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[**More info about this attack in ired.team.**](https://ired.team/offensive-security-experiments/active-directory-kerberos-abuse/domain-compromise-via-dc-print-server-and-kerberos-delegation)\*\*\*\*
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### Mitigation
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* Limit DA/Admin logins to specific services
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* Set "Account is sensitive and cannot be delegated" for privileged accounts.
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