Successfully reported this slideshow.
We use your LinkedIn profile and activity data to personalize ads and to show you more relevant ads. You can change your ad preferences anytime.

Defending Your "Gold"

1,188 views

Published on

This presentation was given at PSConfEU and covers common privilege escalation vectors for Windows systems, as well as how to enumerate these issues with PowerUp.

Published in: Technology
  • Be the first to comment

  • Be the first to like this

Defending Your "Gold"

  1. 1. Protecting Your Gold Will Schroeder, Specter Ops Standard Image Analysis With PowerShell
  2. 2. Agenda • PowerUp • Common Privesc Primitives • Service (Binary) Permissions • %PATH% hijacking • Processes, Threads, and User Rights • Autoruns • Provisioning Leftovers/Grab Bag • “Rotten Potato“ • Custom Software Analysis
  3. 3. • Discovery • Delivery • Exploitation • C2 Installation • Privilege Escalation • Lateral Movement • Data Collection • Data Exfiltration Cyber Kill Chain Discovery Delivery Exploitation C2 Installation Privilege Escalation Lateral Movement Data Exfiltration Data Collection
  4. 4. Privilege Escalation • Most attackers (and us) try to find a way to escalate privileges to local administrator/SYSTEM after initial access is gained • Everyone isn’t a local admin any more! • The two main approaches tend to be 0day/exploits and the abuse of misconfigurations • You should examine your gold base system images every time there’s a major change!
  5. 5. • A self- contained PowerShell tool that automates the audit and exploitation of a number of common privilege escalation PowerUp
  6. 6. • Now part of PowerSploit (.PrivescPowerUp.ps1) • Strict Version 2 compatibility • (Now) doesn’t start any additional processes, nor does it depend on any external binaries • I.E. uses ChangeServiceConfig() instead of “set Svc binPath= malicious command” • Uses PSReflect for Win32 API access PowerUp’s Approach
  7. 7. • Services are a defined Windows securable object • So we can use QueryServiceObjectSecurity() • Services themselves sometimes have misconfigured permissions (rare, but it happens) • More common are misconfigured permissions on the binary associated with the service • If an unprivileged user can replace the binary for a service, they can gain code execution when the service/machine restarts • PowerUp: Vulnerable Services
  8. 8. • When a Windows application tries to load a particular .DLL, it searches specific locations in a predefined order 1. The directory from which the application is loaded 2. The 32-bit system directory (C:WindowsSystem32) 3. The 16-bit system directory (C:WindowsSystem) 4. The Windows directory (C:Windows) 5. The current working directory 6. Any directories that are listed in the PATH environment variable Sidenote: DLL Load Order
  9. 9. • When a process tries to load a DLL, there is a predefined search order for the DLL location • The last search location is any folder in %PATH% • One service on Windows 7 (IKEEXT) tries to load a DLL that doesn’t exist (wlbsctrl.dll) • Translation: if we can write to any folder in %PATH% on a Windows 7 machine (like C:Python27) we can escalate %PATH% Hijacking
  10. 10. • Processes and threads are securable objects as well • Something we’re going to look more heavily heavily into this year • User Rights include specific privileges Processes, Threads, and User Rights
  11. 11. • Anything that’s set to automatically run in a (potentially) elevated context is a candidate for hijacking • For the registry: • Enumerate all autoruns in HKLM • Check if the current user can modify any binary or arguments for any discovered autoruns • PowerUp: Get-ModifiableRegistryAutoRun • For scheduled tasks: • Enumerate scheduled tasks where the current user can modify any file in the associated Hijacking Autoruns and Scheduled Tasks
  12. 12. • We occasionally find left over Unattended.xml answer files that have passwords set for local account provisioning • PowerUp: Get-UnattendedInstallFile • Some Group Policy Preference files contain a decryptable cpassword attribute (Get-GPPPassword…) • These GPOs are sometimes cached on the host • PowerUp: Get-CachedGPPPassword Provisioning Leftovers
  13. 13. • If [HKLM|HKCU|SOFTWAREPoliciesMicrosoftW indowsInstallerAlwaysInstallElevated is set, all .MSI files run elevated… • PowerUp: Get-RegistryAlwaysInstallElevated Misc. Grab-bag
  14. 14. • In late 2016, researchers from FoxGlove Security released an attack called “Rotten Potato” • This allows you to escalate from a service account (or any account with SeImpersonatePrivilege) to SYSTEM • It does this by abusing a bug class disclosed by James Forshaw • DCOM/RPC is tricked into authenticating with NTLM to the same endpoint, and the resulting token is impersonated from an account with impersonation privileges Rotten Potato
  15. 15. • Custom internal development is the most common root cause of escalation vectors we find • Why? Security is hard! Same with a SDL! • Part of our standard process is to search for any custom/internally developed software on any machines we gain initial access to • Bonus points if it’s C#! • This is actually very similar to dynamic malware analysis! Custom Software Analysis
  16. 16. Analysis Demo
  17. 17. Summary • Privilege escalation is sometime that most actors attempt during their attack chain • You should examine your gold image whenever there’s a major modification! • Misconfigurations are often unintentionally introduced due to custom development or third- party applications • PowerUp automates the checks for most of these misconfigurations • You can analyze any custom-developed software pretty easily using existing malware dynamic analysis techniques!
  18. 18. • Now: 15 min break • Grab a coffee • Stay here to enjoy next presentation • Change track and switch to another room • Ask me questions or meet me in a breakout session room afterwards Next Steps...
  19. 19. Questions?
  20. 20. • Will Schroeder (@harmj0y) • http://blog.harmj0y.net | will [at] harmj0y.net • Red teamer and offensive engineer for Specter Ops • Co-founder: • Veil-Framework | Empire/EmPyre | BloodHound • Developer of: • PowerView | PowerUp | current PowerSploit developer • Microsoft CDM/PowerShell MVP • Veteran trainer About_Author

×