27.Attacking Domain Trusts - Cross-Forest Trust Abuse - from Windows

I. Cross-Forest Kerberoasting

Concept: Performing Kerberoasting across domain trusts to obtain credentials for accounts in other domains.

Steps:

1. Enumerate SPNs:

   • Use PowerView:

     Get-DomainUser -SPN -Domain FREIGHTLOGISTICS.LOCAL | select SamAccountName

2. Verify account privileges:

   • Use PowerView:

     Get-DomainUser -Domain FREIGHTLOGISTICS.LOCAL -Identity mssqlsvc | select samaccountname,memberof

3. Perform Kerberoasting:

   • Use Rubeus with the /domain: flag:

     .\Rubeus.exe kerberoast /domain:FREIGHTLOGISTICS.LOCAL /user:mssqlsvc /nowrap

4. Crack the hash:

   • Use Hashcat to crack the obtained hash.

Key Takeaway:

• Exploiting trusts to gain access to privileged accounts in other domains.

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II. Admin Password Re-Use & Group Membership

Password Re-Use:

• Checking for password reuse across domains with bidirectional trusts.

• If an attacker gains credentials in one domain, they might work in another.

Group Membership:

• Enumerating foreign group memberships to find accounts with cross-domain privileges.

Commands:

Get-DomainForeignGroupMember -Domain FREIGHTLOGISTICS.LOCAL
Convert-SidToName S-1-5-21-3842939050-3880317879-2865463114-500

Verify Access:

Enter-PSSession -ComputerName ACADEMY-EA-DC03.FREIGHTLOGISTICS.LOCAL -Credential INLANEFREIGHT\administrator

Key Takeaway:

• Exploiting weak password management and misconfigured group memberships.

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III. SID History Abuse - Cross Forest

Concept:

• Abusing SID history across forest trusts when SID filtering is not enabled.

• Allows accounts to retain privileges from their original domain after migration.

Mechanism:

• Adding SIDs from one forest to the sidHistory attribute of accounts in another.

• The user retains the rights of the added SID in their token.

Key Takeaway:

• Exploiting misconfigurations in trust relationships to maintain or gain privileges.

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IV. Important Considerations:

• Cross-forest attacks can significantly expand an attacker's reach.

• Enumeration and verification are crucial steps.

• Password reuse is a very common issue.

• SID filtering is very important to have enabled.