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Hidden Rootkits in Windows

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Agenda

What is a rootkit?Kernal mode vs user modePopular and New rootkitsHistory of RootkitsWhat can they hideDEMO – Hacker Defender Anatomy 101How they hide and go undetectedDEMO - Hacker Defender In Action!DEMO – Covert ChannelsDEMO – FUToDetection, Protection and RemovalDEMO – DetectionHardware Virtualization RootkitsVistaTrends

Overview

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

What is a rootkit?

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.

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.

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

Windows Architecture

Reference: http://www.microsoft.com

Windows USER,

GDI

Graphics drivers

NTDLL.DLL

System threads

System Processes· LSASS· Service Control Manager· Session manager· Winlogon

Services· Services.exe· Spoolsvc.exe· Svchost.exe· Winmgt.exe

Applications· Explorer· Task manager· User applications

Subsystems· OS/2· POSIX· Windows· Windows DLLs

System Service Dispatcher

(Kernel mode callable interfaces)

Config Manager (registry)

File System Cache

I/O Manager

Local Procedure

Call

Object Manager

Plug & Play

Processess & Threads

Security Reference

Monitor

Virtual Memory

Ring 0Kernel Mode

Ring 3User Mode

Hardware Abstraction Layer

Device & File Sys Drivers Kernel

History of Rootkits

PrimitiveBinary file replacement (password logging / UNIX)Hiding traces/tracks (log cleaners)

PrimitiveBinary file replacement (password logging / UNIX)Hiding traces/tracks (log cleaners)

More advanced hiding - “stealthy” (Hxdef,HE4Hook)Hooking techniques

More advanced hiding - “stealthy” (Hxdef,HE4Hook)Hooking techniques

Direct dynamic manipulation of kernel structures (FU)Difficult for detection software to identify

Direct dynamic manipulation of kernel structures (FU)Difficult for detection software to identify

Advanced Memory hooking/hiding (Shadow Walker)Used in collusion with 3rd Generation rootkitExtremely “stealthy”

Advanced Memory hooking/hiding (Shadow Walker)Used in collusion with 3rd Generation rootkitExtremely “stealthy”

FirstGeneration

SecondGeneration

ThirdGeneration

FourthGeneration

Hardware VirtualizationBoot Root KitsHardware VirtualizationBoot Root Kits

FifthGeneration

Popular Rootkits

AFX Rootkit 2005FUHacker DefenderHE4HookNT Root

NTFSHiderNTIllusionVanquishWinlogon Hijack

New Rootkits

FUToKIrcBotSubVirtShadow Walker

BluePill (PoC)BootRoot and VBootKit

Commercial Stealth

Sony DRMMr. & Mrs. Smith DVD (Alpha-Disc DRM)Norton System WorksHide Folders XPTracking and Monitoring software

Commercially available products that use rootkit type technologies.

What can they hide

Covert Channels Custom GINA’s Files and Directories Processes Registry Keys Services TCP/UPD portsMemory pages (New) VM’s (New)

How they hide and go undetected

Kernel Native API hookingUser Native API hookingDynamic Forking of Win32 EXEDirect Kernel Object Manipulation (DKOM)Interrupt Descriptor Table HookingMemory Hooking (Shadow Walker)

Reference: www.security.org.sg / www.hbgary.com / www.rootkit.com

DEMO Network

172.16.0.x

Internet

Windows Server 2003SMTP ServiceDomain ControllerIP: 172.16.0.1rk-win2k3.domain.com

Windows Server 2003ISA 2004 FirewallIP: 172.16.0.10rk-isa.domain.com

Windows XPIP: 10.10.8.200winxp.attacker.com

Windows XPIP: 172.16.0.xrk-winxp.domain.com

IP: 10.10.8.100

DEMO Introduction

Hacker Defender - Anatomy 101Hxdef100.exeHxdef100.iniHxdefdrv.sys (Embedded in hxdef100.exe)

Rdrbs100.exeRdrbs100.iniBdcli100.exe

Reference: http://hxdef.czweb.org

DEMO

Hacker Defender – In Action!Security Compromise - ExploitAvoiding Antivirus DetectionHiding Folders/FilesHiding ServicesHiding TCP Ports

Hacker Defender – Covert ChannelBackdoor shell access via SMTP

Covert Channel Summary

Firewall

Port 25 is intercepted by Backdoor

2Backdoor

ServerIntercept TCP:25

Special 256 bit key is sent

1

Remote Shell

TCP:100

SMTP ServiceTCP:25

Windows 2003

Normal email is sent to the SMTP service

1

2

33

4 Remote Shell on TCP:100 started

4

Backdoor Client Internet

DEMO

FUToSecurity Compromise - ExploitAvoiding Antivirus DetectionChanging Security TokenHiding Process

Detection

How to detect rootkits?Darkspy 1.0.5

F-Secure BlackLight Beta 2.2.1061

GMER 1.0.12.12244

IceSword 1.20

KProcCheck 0.2-beta2

Malicious Software Removal Tool V1.29 5/12/2007

Process Magic by WinEggDrop V1.0

RootKit Shark 3.11

RootkitRevealer 1.7

Strider (Microsoft) beta

System Virginity Verifier 2.3

Windows Defender 1.1.1505.0

UnHackMe 4.5

DEMO

Detecting rootkitsF-Secure BlacklightGMERRootkit RevealerIceSword

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

Detection Results

Name Version AFX Rootkit 2005 FUHacker

DefenderVanquish Notes

Blacklight 2.2.1037 Yes Yes Yes Yes

Flister 0.1 Yes No *1 Yes Yes Need to type in the exact dir path

Keensense 2.0 Yes Yes Yes No Installs system driver and requires a reboot. Unstable.

Process Guard 3.150 Yes Yes Yes Yes Install requires a reboot. All Global Protection optiosn manually turned on. Needs to “learn” a baseline of the system.

GMER 1.0.10.10111 Yes Yes Yes Yes Choice of reboot for advanced features

IceSword 1.18 Yes Yes Yes Yes Choice of reboot for advanced features

Rootkit Revealer 1.55 Yes No Yes Yes

Strider beta Yes No *1 Yes Yes Hidden directory/file compare of comprimised state and clean state from a WinPE boot CD using windiff.

Detection Summary

All “stock” rootkits discovered with various detection toolsCustom recompiled rootkits by pass antivirus detectionCommercially available customized rootkits that hide files, services, processes, registry keys would not be detected in the compromised OS

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 processorMicrosoft Vista Beta 2

SUMMARY: THIS IS NOT AN AMD OR INTEL NOR VISTA OR MAC ISSUE!

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.

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 shellcodeAsk kernel to call the driver code which was just replaced

“Fixed” in Vista RC2 – by disabling raw disk access from user mode (including administrator)

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.

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 virtualizationBP installs itself on the fly and does not introduce any modifications to BIOS nor hard diskBP 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 technologyChanges in hardware (processor) could allow for easy BP detection

Protection

Defence in Depth practices!Application Layer firewallsAdd rootkit detection and removal software to your toolkitBaseline your systems in another kernel (WinPE) using the Microsoft Strider technique for comparing modified/added binaries on a regular basis

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/ServerMicrosoft Shared Computer Toolkit v1.1Faronics Deep FreezeSymantec Norton GoBackWinternals Recovery Manager

Once a machine has been compromised, the only true cleaning method is to low-level format and reload!

Trends 1 of 2

It’s a cat and mouse gameAs 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

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, VBootKit)

Virtual Machine rootkits

Database rootkits (presented in concept by Alexander Kornbrust at BH2005)

Hardware based rootkit detectionIntel Rootkit detection (Code name: LaGrande)

TPM (Trusted Platform Module)

Co-Pilot (PCI card) http://www.komoku.com

VISTA

Windows DefenderMicrosoft plans to move device drivers out of the kernel and in to the user level (starting with Vista)Address Space Layout Randomization (ASLR)Digital Signatures for Kernel Modules on x64-based Systems Running Windows VistaMicrosoft Patch Guard on x64 Based Systems

Reference: http://www.microsoft.com

Need to Know

Stop rootkits from entering and executing in your environment.Stop rootkits from entering and executing in your environment.Prevention

Non-critical systems can be cleaned and/or reloaded.Critical systems require professional assistance, particularly if forensic evidence is desired.

Non-critical systems can be cleaned and/or reloaded.Critical systems require professional assistance, particularly if forensic evidence is desired.

Response

http://www.rootkit.comhttp://www.antirootkit.comParticipate in the Toronto Area Security Klatch http://www.task.to

http://www.rootkit.comhttp://www.antirootkit.comParticipate in the Toronto Area Security Klatch http://www.task.to

LearnMore

Security Education Conference in Toronto

November 20 – 21, 2007, MTCC, Toronto, ON, Canadahttp://www.sector.ca/

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