Externally Testing Modern AD Domains - Arcticcon
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Externally federated domain endpoints are an exciting target for Red Team assessments. While often overlooked, externally federated domain services can provide multiple access points to an internal network, from the internet. This talk will cover enumeration of federated domains (ADFS and AzureAD), the enumeration of federated services (Office365, Skype for Business, etc.), and attacks that you can leverage against these endpoints to gain access to an internal network. Additional PowerShell tools will be included in the talk to help you automate these attacks.
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Externally Testing Modern AD Domains - Arcticcon
- 1. Externally Testing Modern Active Directory Domains Karl Fosaaen
- 2. Introductions • Who am I? ‒Karl Fosaaen • What do I do? ‒Wear lots of hats ‒Pen Testing ‒Password Cracking ‒Social Engineering ‒Blog ‒DEF CON Swag Goon ‒Pinball Repair
- 3. Slides Overview • Intro • Domain Enumeration • Authentication Endpoint Enumeration ‒ Graph API ‒ ADFS ‒ Office 365 • Microsoft Online login • Exchange • Skype for Business • Pivoting to the internal network • Attack Mitigations • Conclusions
- 4. Intro • Standard ExPen Process ‒ Enumeration of domain info • Services • Username/Email recon ‒ Exploitation of issues • Phishing • Web Vulnerabilities • Weak/Default logins ‒ Pivot to internal network ‒ Escalate internally
- 6. Domain Federation Overview Federation can mean many things ‒ Domain to Domain ‒ Domain to Microsoft ‒ Arbitrary meanings based off of forum posts
- 7. Managed Domain Overview Diagram of (Managed) O365 federation
- 8. Federated Domain Overview Diagram of (Federated) O365 federation
- 9. Domain Enumeration Side Note: • Office365 had an Authentication Bypass issue ‒ Insecure SAML assertions ‒ Affected all federated Office365 domains ‒ They called out this method in their blog post Source: http://www.economyofmechanism.com/office365- authbypass.html
- 10. Domain Enumeration • Using Microsoft Online
- 11. Domain Enumeration • Example user check request
- 12. Domain Enumeration • Microsoft’s Responses ‒ Federated Domain ‒ Microsoft Managed Domain
- 13. Domain Enumeration • Grab the PowerShell script from NetSPI • https://github.com/NetSPI/PowerShell/blob/master/Get- FederationEndpoint.ps1
- 14. Domain Enumeration ‒ Federated Domain ‒ Microsoft Managed Domain https://blog.netspi.com/using-powershell-identify-federated-domains/ https://github.com/NetSPI/PowerShell/blob/master/Get-FederationEndpoint.ps1
- 15. Domain Enumeration • Multiple domains at once https://blog.netspi.com/using-powershell-identify-federated-domains/ https://github.com/NetSPI/PowerShell/blob/master/Get-FederationEndpoint.ps1
- 16. Domain Enumeration • What’s the current exposure? ‒ 47,455 (4.7%) of the top 1 Million have “ms=ms*” DNS records • Personal Experience ‒ Managed/Federated/Neither 50% 40% 10%
- 18. Graph API
- 19. Graph API Overview • Using the Graph API ‒ This works for federated and managed domains
- 20. Graph API – Credential Brute Forcing • Using the Graph API $token = Get-GraphAPIToken -TenantName DOMAIN_GOES_HERE Github – https://github.com/NetSPI/PowerShell/blob/master/Get- GraphAPIToken.ps1 *Requires Azure AD PowerShell Modules
- 21. Graph API – Credential Brute Forcing • Using the Graph API
- 22. Graph API – User Enumeration • Get-GraphData -Token $token -Tenant DOMAIN_GOES_HERE -Resource users Github – https://github.com/NetSPI/PowerShell/blob/master/Get- GraphAPIToken.ps1
- 23. ADFS
- 24. ADFS Overview Active Directory Federation Services (AD FS) “is a standards-based service that allows the secure sharing of identity information between trusted business partners (known as a federation) across an extranet.” Source: https://msdn.microsoft.com/en-us/library/bb897402.aspx
- 25. ADFS – Credential Brute Forcing • Get-FederationEndpoint gives us the appropriate command to run for the domain ‒ Federated Domain
- 26. ADFS – Credential Brute Forcing • Invoke-ADFSSecurityTokenRequest* Invoke-ADFSSecurityTokenRequest -ClientCredentialType UserName -ADFSBaseUri https://adfs.example.com/ -AppliesTo https://adfs.example.com/adfs/services/trust/13/usernamemixed -UserName 'karl.fosaaen‘ -Password 'Winter2016‘ -Domain ‘example.com‘ -OutputType Token -SAMLVersion 2 -IgnoreCertificateErrors https://blogs.msdn.microsoft.com/besidethepoint/2012/10/17/request-adfs-security- token-with-powershell/
- 27. ADFS – User Enumeration • Go back a few slides to the GraphAPI information
- 28. Office365
- 29. Office365 Overview • Office365 ‒Azure AD ‒Exchange ‒Skype for Business • Credential Brute Force • User Enumeration
- 30. Setting Up Your Test Environment • Install the Azure AD PowerShell Module • https://msdn.microsoft.com/en- us/library/azure/jj151815(v=azure.98).aspx
- 31. Office365 - Credential Brute Forcing • Get-FederationEndpoint gives us the appropriate command to run for the domain ‒ Microsoft Managed Domain
- 32. Office365 - Credential Brute Forcing • Connect-msolservice – AzureAD PS Module
- 33. Office365 – User Enumeration 1. $msolcred = get-credential 2. connect-msolservice -credential $msolcred 3. Get-MsolUser -All | ft –AutoSize • This also works for apps (Web/Thick) using AzureAD for account management
- 34. Office365 - Exchange • If the domain uses Office365, you can most likely connect to Office365 Exchange with PowerShell
- 35. Exchange – Credential Brute Forcing $PWord = ConvertTo-SecureString -String 'Summer2016' -AsPlainText –Force $credentials = New-Object -TypeName "System.Management.Automation.PSCredential " -ArgumentList "test@example.com", $PWord
- 36. Exchange – Credential Brute Forcing $Session = New-PSSession -ConfigurationName Microsoft.Exchange -ConnectionUri https://outlook.office365.com/powershell- liveid/ -Credential $credentials -Authentication Basic –AllowRedirection Import-PSSession $Session
- 37. Exchange – User Enumeration Invoke-Command -ConfigurationName Microsoft.Exchange -ConnectionUri https://outlook.office365.com/powershell- liveid/ -Credential $Credentials -Authentication Basic -AllowRedirection -ScriptBlock {Get-Recipient -ResultSize unlimited} | Export-CSV c:tempemail_users.csv -NoTypeInformation
- 38. Skype For Business – Overview • Formerly Lync, now Skype for Business • Commonly Federated with other domains ‒ Great for credential guessing, user enumeration, and social engineering
- 39. Skype For Business – Tools • Grab the PowerShell modules from NetSPI • https://github.com/NetSPI/PowerShell/blob/master/Power Skype.ps1
- 40. Skype For Business – Credential Brute Forcing ‒ Get-SkypeLoginURL • In progress ‒ Invoke-SkypeLogin ‒ Credit to @Nyxgeek for the auth endpoints
- 41. Skype For Business – Blind User Enumeration • Using a federated Skype account, we can enumerate other federated Skype users • Just open a chat with them
- 42. Skype For Business – Blind User Enumeration • Or we can just chat with these CEOs
- 43. Skype For Business – Blind User Enumeration • Blind User enumeration (email confirmation) requires the SDK ‒ Also requires a signed in federated user • You can use guessed credentials (autodiscover) • or pay Microsoft for a cheap federated account • ~$6/month
- 44. Skype For Business – Tools • Install Skype for Business and the Lync SDK ‒ Requires Visual Studio 2010 for the easiest install https://www.microsoft.com/en-us/download/details.aspx?id=36824
- 45. Skype For Business – Blind User Enumeration • Let’s just wrap it with PowerShell Get-SkypeStatus -inputFile test_emails.txt | ft -AutoSize
- 46. Skype For Business – Blind User Enumeration
- 47. Skype For Business – Blind User Enumeration Demo • Get-SkypeStatus -inputFile "C:TempLiveAdmins.txt" | ft -AutoSize • It helps if we run it a couple of times…
- 48. Skype For Business – Blind User Enumeration
- 49. Skype4Business – Authenticated User Enumeration • Or if it’s autodiscover enabled, you can list the users from the Skype user’s contact list
- 50. Pivoting to the Internal Network
- 51. Pivoting to the Internal Network – Exchange • Attacking Email Accounts ‒ If Autodiscover is enabled, adding an account can be done from anywhere ‒ Email is interesting, but I’d like a shell ‒ This can not be done programmatically with PowerShell (*Easily) ‒ “Malicious Outlook Rules” • Nick Landers – Silent Break Security ‒ “MAPI over HTTP and Mailrule Pwnage” • Etienne - sensepost
- 52. Pivoting to the Internal Network – Skype • Send messages from OWA or Skype for Business ‒ Autodiscover is also handy here ‒ People will trust their co-workers • “Can you look over this word doc for me?”
- 53. Pivoting to the Internal Network – Skype Demo • Get-SkypeStatus -email karl.fosaaen@netspi.com • Invoke-SendSkypeMessage -email karl.fosaaen@netspi.com -message "Hello from Derbycon" • for ($i = 0; $i -lt 10; $i++){Invoke- SendSkypeMessage -email karl.fosaaen@netspi.com -message "Hello $i"}
- 54. Pivoting to the Internal Network – Skype
- 55. Pivoting to the Internal Network – Skype
- 56. Pivoting to the Internal Network – VPN • Single Factor VPN Example ‒ Enumerated user emails on LinkedIn ‒ Guessed passwords against MSOnline with PowerShell ‒ Enumerated VPN interfaces ‒ Logged in with guessed credentials ‒ GPP -> Local admin on DA system ‒ DCSync • “Store passwords using reversible encryption”
- 57. Pivoting to the Internal Network – Other • Other Routes ‒ Single Factor Services • Management Protocols • RDP • SSH • Terminal Services – Web Based • Citrix • VDI • Etc.
- 58. Pivoting to the Internal Network – OneDrive • Malicious OneDrive Documents ‒ Can’t use macros in the online version of excel
- 59. Pivoting to the Internal Network - SharePoint • Malicious SharePoint Documents ‒ Same concept as OneDrive, just a different platform ‒ Backdoor a document ‒ Edit pages
- 61. Attack Mitigations • Enable Dual factor authentication for external endpoints* *On all channels
- 62. Attack Mitigations • Limit federation to trusted domains • Limit exposed services surface area • Monitor your Federated and Azure endpoints • Enforce strong password requirements
- 63. Conclusions
- 64. Conclusions • Lots of authentication endpoints on the Internet • There’s always a $SEASON$YEAR password out there • There are several ways to pivot internally with credentials • MFA will help reduce your risk
- 65. Next Steps • Yet another framework for pen testing… ‒ Enumerate all of the potential AD authentication endpoints for a domain • And again, AutoDiscover is handy here ‒ Include credential brute force methods for each interface type ‒ Easy mode, autopwn, etc. • Give it a domain, user list, and go for it ‒ Try to keep it dependency free • Easier to use • More portable