Hidden Rootkits in Windows

1. Prepared by: CMS Consulting Inc. Confidential CMS Consulting Inc. Hidden Rootkits in Windows Presented by: Brian Bourne, CISSP, MCSE:Security

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4. 1. ~~~~~~~~~ 2. ~~~ ~~ ~~ 3. ~~~~ AGENDA • What is a rootkit? • Kernal mode vs user mode • Popular and New rootkits • History of Rootkits • What can they hide • DEMO – Hacker Defender Anatomy 101 • How they hide and go undetected • DEMO - Hacker Defender In Action! • DEMO – Covert Channels • DEMO – FUTo • Detection, Protection and Removal • DEMO – Detection • Hardware Virtualization Rootkits • Vista • Trends

5. Overview What is a rootkit? • A root kit is a set of tools used by an intruder after cracking a computer system. These tools can help the attacker maintain his or her access to the system and use it for malicious purposes. Root kits exist for a variety of operating systems such as Linux, Solaris, and versions of Microsoft Windows Reference: http://en.wikipedia.org/wiki/Rootkit

6. Types of rootkits 1 of 3 Persistent RootkitsA persistent rootkit is one associated with malware that activates each time the system boots. Because such malware contain code that must be executed automatically each system start or when a user logs in, they must store code in a persistent store, such as the Registry or file system, and configure a method by which the code executes without user intervention. Memory-Based RootkitsMemory-based rootkits are malware that has no persistent code and therefore does not survive a reboot.

7. Types of rootkits 2 of 3 User-mode RootkitsThere are many methods by which rootkits attempt to evade detection. Example: • a user-mode rootkit might intercept all calls to the Windows FindFirstFile/FindNextFile APIs, which are used by file system exploration utilities, including Explorer and the command prompt, to enumerate the contents of file system directories. • When an application performs a directory listing that would otherwise return results that contain entries identifying the files associated with the rootkit, the rootkit intercepts and modifies the output to remove the entries.

8. Types of rootkits 3 of 3 Kernel-mode RootkitsKernel-mode rootkits can be even more powerful since, not only can they intercept the native API in kernel-mode, but they can also directly manipulate kernel-mode data structures. A common technique for hiding the presence of a malware process is to remove the process from the kernel's list of active processes. Since process management APIs rely on the contents of the list, the malware process will not display in process management tools like Task Manager or Process Explorer. Reference: http://www.sysinternals.com

9. Windows Architecture

10. Primitive • Binary file replacement (password logging / UNIX) • Hiding traces/tracks (log cleaners) 1 FirstGeneration • More advanced hiding - “stealthy” (Hxdef,HE4Hook) • Hooking techniques 2 SecondGeneration • Direct dynamic manipulation of kernel structures (FU) • Difficult for detection software to identify 3 ThirdGeneration • Advanced Memory hooking/hiding (Shadow Walker) • Used in collusion with 3rd Generation rootkit • Extremely “stealthy” • Hardware Virtualization 4 5 FifthGeneration FourthGeneration History of Rootkits Reference: http://www.phrack.org/archives/63/p63-0x08_Raising_The_Bar_For_Windows_Rootkit_Detection.txt

11. AFX Rootkit 2005 FU Hacker Defender HE4Hook NT Root NTFSHider NTIllusion Vanquish Winlogon Hijack Popular Rootkits

12. New Rootkits • FUTo • KIrcBot • SubVirt • Shadow Walker • BluePill (PoC)

13. Commercial Stealth Commercially available products that use rootkit type technologies. • Sony DRM • Mr. & Mrs. Smith DVD (Alpha-Disc DRM) • Norton System Works • Hide Folders XP • Tracking and Monitoring software

14. What can they hide • Covert Channels • Custom GINA’s • Files and Directories • Processes • Registry Keys • Services • TCP/UPD ports • Memory pages (New) • VM’s (New)

15. How they hide and go undetected • Kernel Native API hooking • User Native API hooking • Dynamic Forking of Win32 EXE • Direct Kernel Object Manipulation (DKOM) • Interrupt Descriptor Table Hooking • Memory Hooking (Shadow Walker) Reference: www.security.org.sg / www.hbgary.com / www.rootkit.com

16. DEMO Network

17. DEMO Introduction • Hacker Defender - Anatomy 101 • Hxdef100.exe • Hxdef100.ini • Hxdefdrv.sys (Embedded in hxdef100.exe) • Rdrbs100.exe • Rdrbs100.ini • Bdcli100.exe Reference: http://hxdef.czweb.org DEMO

18. DEMO Hacker Defender – In Action! • Security Compromise - Exploit • Avoiding Antivirus Detection • Hiding Folders/Files • Hiding Services • Hiding TCP Ports Hacker Defender – Covert Channel • Backdoor shell access via SMTP DEMO

19. Covert Channel Summary

20. DEMO FUTo • Security Compromise - Exploit • Avoiding Antivirus Detection • Changing Security Token • Hiding Process DEMO

21. Detection How to detect rootkits?

22. DEMO Detecting rootkits • F-Secure Blacklight • GMER • Rootkit Revealer • IceSword DEMO

23. Detection Results *1 Could not detect FU because it does not hide folders/files. Only processes.

24. Detection Summary • All “stock” rootkits discovered with various detection tools • Custom recompiled rootkits by pass antivirus detection • Commercially available customized rootkits that hide files, services, processes, registry keys would not be detected in the compromised OS

25. Hardware Virtualization Rootkits • Dino Dai Zovi presented an essentially undetectable hypervisor rootkit using: • Intel VT processor • Mac OS-X • “Vitriol” to be demo’d at BlueHat • Joanna Rutkowska presented an essentially undetectable hypervisor rootkit using: • AMD Pacifica processor • Microsoft Vista Beta 2 • SUMMARY: THIS IS NOT AN AMD OR INTEL NOR VISTA OR MAC ISSUE!

26. Hardware Virtualization Rootkits • Preventing detection was a design goal: • – “There is no software-visible bit whose setting indicates whether a logical processor is in VMX non-root operation. This fact may allow a VMM to prevent guest software from determining that it is running in a virtual machine” -- Intel VT-x specification • The design goals of AMD and Intel were to provide full virtualization. This means FULL virtualization. • There is no hardware bit or register that indicates that the processor is running in VMX non-root mode • Read Dino and Joanna’s presentations for details regarding new CPU instructions and how hypervisors work.

27. Bypassing Vista Kernel Signed Drivers • Well Joanna did have some extra complexity to deal with because of Vista requiring all kernel drivers to be signed. • Essentially, she figured out a way to cause it to page out null.sys, then modified the pagefile.sys directly using raw disk access to get Vista to run her rootkit. The process: • Allocate lots of memory to cause unused drivers code to be paged • Replace the paged out code (inside pagefile) with some shellcode • Ask kernel to call the driver code which was just replaced • “Fixed” in Vista RC2 – by disabling raw disk access from user mode (including administrator)

28. BP Detection • Some ideas for BluePill detection were presented by both Dino and Joanna. Essentially they are: • Attempt to use VMX to create a VM • Bluepill a box with Bluepill – although this exception could be handled and the second Bluepill to run would end up being virtualized also) • Attempt to detect VM exit latency • Dino demo’d using CPUID, but a number of instructions cause a VM Exit and you could measure latency. Although the timer could be altered by the Bluepill and hence would require an external time source. How could is your stop watch? • Joanna came up with an undisclosed method to blue screen a BluePill’ed box, but that’s not really great detection.

29. Hardware Virtualization Rootkits Bottom line • Arbitrary code can be injected into Vista x64 kernel despite code signing requirement, and in really any other operating system. • This could be abused to create “Blue Pill” based malware on processors supporting virtualization • BP installs itself on the fly and does not introduce any modifications to BIOS nor hard disk • BP can be used in many different ways to create the actual malware • BP should be undetectable in any practical way (when fully implemented) • Blocking BP based attacks on software level will also prevent ISVs from providing their own VMMs and security products based on SVM technology • Changes in hardware (processor) could allow for easy BP detection

30. Protection • Defence in Depth practices! • Application Layer firewalls • Add rootkit detection and removal software to your toolkit • Baseline your systems in another kernel (WinPE) using the Microsoft Strider technique for comparing modified/added binaries on a regular basis

31. Removal • Rootkit removal tools (eg. “Unhackme” by Greatis Software, F-Secure Blacklight, GMER, IceSword) • Clean from another kernel (eg. BackTrack, WinPE, etc) • Use technology that reverts back to a previous state if your environment allows for it: • Undo disks in Microsoft Virtual PC/Server • Microsoft Shared Computer Toolkit v1.1 • Faronics Deep Freeze • Symantec Norton GoBack • Winternals Recovery Manager • Once a machine has been compromised, the only true cleaning method is to low-level format and reload!

32. Trends 1 of 2 It’s a cat and mouse game • As rootkit detection methods/signatures are updated; so are the techniques/methods of the rootkits evading detection; just like viruses but much more sophisticated • Encrypting the memory pages where the rootkit is running to avoid detection • Polymorphism • Spyware and Viruses utilizing functions of rootkits to hide their presence and payload; This has already happened and will continue to escalate to an extremely “stealthy” version

33. Trends 2 of 2 • Memory Hiding (e.g. Shadow Walker) • Using other system writeable memory locations. (e.g. VideoCardKit, MTDWin, ACPI, BIOS) • Boot sector rootkits (e.g. BootRootKit) • Virtual Machine rootkits • Database rootkits (presented in concept by Alexander Kornbrust at BH2005) • Hardware based rootkit detection • Intel Rootkit detection (Code name: LaGrande) • TPM (Trusted Platform Module) • Co-Pilot (PCI card) http://www.komoku.com

34. VISTA • Windows Defender (Beta 2) • Microsoft plans to move device drivers out of the kernel and in to the user level. • Address Space Layout Randomization (ASLR) • Digital Signatures for Kernel Modules on x64-based Systems Running Windows Vista • Microsoft Patch Guard on x64 Based Systems Reference: http://www.microsoft.com

35. Stop rootkits from entering and executing in your environment. • Non-critical systems can be cleaned and/or reloaded. • Critical systems require professional assistance, particularly if forensic evidence is desired. • http://www.rootkit.com • http://www.antirootkit.com • Participate in the Toronto Area Security Klatch http://www.task.to Need to Know Prevention Response LearnMore

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37. Contacting Us. @ • Brian Bourne, President – brian@cms.ca • Robert Buren, VP Business Development – robert@cms.ca CMS Consulting Inc. – http://www.cms.ca/ CMS Training – http://www.cms.ca/training/ Toronto Area Security Klatch – http://www.task.to/