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PSConfEU - Offensive Active Directory (With PowerShell!)

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This talk covers PowerShell for offensive Active Directory operations with PowerView. It was given on April 21, 2016 at the PowerShell Conference EU 2016.

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PSConfEU - Offensive Active Directory (With PowerShell!)

  1. 1. Offensive Active Directory Will Schroeder (@harmj0y) With PowerShell!
  2. 2. Agenda • Offensive Active Directory 101 • Hunting for Users • Local Administrator Enumeration • GPO Enumeration and Abuse • Active Directory ACLs • Domain Trusts
  3. 3. Offensive AD 101 • Red teams and ‘real’ bad guys have been abusing AD for years, but not much offensive AD information has existed publicly (until recently) • See http://adsecurity.org/ • A lot of what we do on a red team is essentially just (authorized) domain administration • We find misconfigurations and chain access/trust relationships to turn one
  4. 4. PowerView • A pure PowerShell domain/network situational awareness tool • Version 2.0 compliant • Fully self-contained and loadable in memory • Now part of PowerSploit™ (not really trademarked) • Many modules are implemented in Empire • Built to automate large components of the tradecraft on our red team engagements
  5. 5. Sidenote “The best tool these days for understanding windows networks is Powerview [1].” -Phineas Fisher http://pastebin.com/raw/0SNSvyjJ
  6. 6. Hunting for Users • On nearly every engagement, we end up wanting to know where specific users are logged in • We break this down into: • Pre-elevated access, where we have regular domain user privileges. This is out “lateral spread” phase • Post-elevated access, where we have some type of elevated (e.g. Domain Admin) access. This is usually our ‘demonstrate impact’ phase
  7. 7. Win32 API Access • Several techniques we rely on for user- hunting depend on various Windows API calls • Specifically NetWkstaUserEnum and NetSessionEnum • There are several methods to access these API calls through PowerShell • C# Add-Type, straight reflection, PSReflect • See Matt Graeber’s US PowerShell Summit talk on Win32 API access for more details
  8. 8. • Windows allows any domain-authenticated user to enumerate the members of a local group on a remote machine • Either through the NetLocalGroupGetMembers Win32 API call or the WinNT service provider • “Derivative Local Admin” • Alice is (effectively) an admin on Bob’s machine, and Bob is (effectively) an admin on Eve’s machine • Alice can derive Eve’s rights though compromising and leveraging Bob’s credentials Local Administrator Enumeration
  9. 9. • Machines obviously have to somehow determine what users have administrative rights • Usually set through restricted groups or group policy preferences • These GPO policies are accessible by anyone on the domain • From of offensive perspective, we can often query a domain controller, and determine who has administrative rights to what machines GPO Enumeration and Abuse
  10. 10. • Very few organizations properly audit AD ACLs or alert on their alteration • Almost every organization has some kind of misconfiguration SOMEWHERE in the object access rights in their domain structure • This is also a great candidate place for ‘sneaky’ persistence! Active Directory ACLs
  11. 11. • Trusts allow separate domains to form inter-connected relationships • Often utilized during acquisitions (i.e. forest trusts or cross-link trusts) • A trust just links up the authentication systems of two domains and allows authentication traffic to flow between them • Allows for the possibility of privileged access between domains, but doesn’t guarantee it* Domain Trusts
  12. 12. • Mimikatz Golden Tickets now accept SidHistories though the new /sids:<X> argument • If you compromise a DC in a child domain, you can create a golden ticket with the “Enterprise Admins” in the SID history • This can let you compromise the parent domain! • The FOREST is the trust boundary, not the domain! Sidenote: The Mimikatz Trustpocalypse
  13. 13. Summary • There’s a lot of overlap between offensive engagements and legitimate domain administration • You can find where users are logged in WITHOUT elevated domain privileges • You can enumerate the local users of a remote machine WITHOUT elevated domain privileges • Domain trusts can easily be enumerated,
  14. 14. Questions?
  15. 15. • Will Schroeder (@harmj0y) • http://blog.harmj0y.net | will [at] harmj0y.net • Security researcher and red teamer for Veris Group‘s Adaptive Threat Division • Offensive open-source developer: • Veil-Evasion, Empire, PowerSploit • Recent Microsoft CDM/PowerShell MVP About_Author
  16. 16. • The Mimikatz Trustpocalypse brought to you by: • Benjamin Delpy (@gentilkiwi) • Sean Metacalf (@pyrotek3) - http://adsecurity.org • My Active Directory background brought to you by: • Carlos Perez (@darkoperator) • Sean Metcalf (@pyrotek3) - http://adsecurity.org • Get PowerView: About_References

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