REboot: BootkitsRevisited

Bootkit

Basics

State of the art

REboot

Conclusion

Samuel Chevet

REboot: Bootkits Revisited

Samuel Chevet

29 May 2014

REboot: BootkitsRevisited

Bootkit

Basics

State of the art

REboot

Conclusion

Samuel Chevet

Agenda

Describe what a bootkit isHow the Windows boot process worksState of the art in the real worldREboot projectConclusion

REboot: BootkitsRevisited

Bootkit

Basics

State of the art

REboot

Conclusion

Samuel Chevet

Plan

1 Bootkit

REboot: BootkitsRevisited

Bootkit

Basics

State of the art

REboot

Conclusion

Samuel Chevet

Rootkit

Type of "malicious" softwareKernel-LandFull controlHide malicious stuffAdding / Replacing portions of OSProprietary software protections used it sometimes

REboot: BootkitsRevisited

Bootkit

Basics

State of the art

REboot

Conclusion

Samuel Chevet

Bootkit

Problem with x64 versionDriver signing is mandatoryBuy or steal certificate ?Kernel Protection

New attackCompromise the boot processSubvert 64-bit kernel mode driver signingLoad malicious driverBotnets: Spam, steal credentials, DDOS, . . .

REboot: BootkitsRevisited

Bootkit

Basics

State of the art

REboot

Conclusion

Samuel Chevet

Bootkit

Problem with x64 versionDriver signing is mandatoryBuy or steal certificate ?Kernel Protection

New attackCompromise the boot processSubvert 64-bit kernel mode driver signingLoad malicious driverBotnets: Spam, steal credentials, DDOS, . . .

REboot: BootkitsRevisited

Bootkit

Basics

State of the art

REboot

Conclusion

Samuel Chevet

Bootkit

Bootkits’ evolution (http://www.welivesecurity.com/ c©)

http ://www.welivesecurity.com/

REboot: BootkitsRevisited

Bootkit

BasicsBoot process

BIOS

MBR

VBR

BootMGR

Winload

Chain of trust

State of the art

REboot

Conclusion

Samuel Chevet

Plan

2 BasicsBoot process

BIOSMBRVBRBootMGRWinload

Chain of trust

REboot: BootkitsRevisited

Bootkit

BasicsBoot process

BIOS

MBR

VBR

BootMGR

Winload

Chain of trust

State of the art

REboot

Conclusion

Samuel Chevet

Boot process

REboot: BootkitsRevisited

Bootkit

BasicsBoot process

BIOS

MBR

VBR

BootMGR

Winload

Chain of trust

State of the art

REboot

Conclusion

Samuel Chevet

Plan

2 BasicsBoot process

BIOSMBRVBRBootMGRWinload

Chain of trust

REboot: BootkitsRevisited

Bootkit

BasicsBoot process

BIOS

MBR

VBR

BootMGR

Winload

Chain of trust

State of the art

REboot

Conclusion

Samuel Chevet

BIOS

Initialize and test the system hardware componentsExecuted in Real modeTransfer execution to some other medium :

Disk driveCD-ROMNetwork boot

Load first sector of hardware drive at 0000:7C00First sector is called Master Boot Record(MBR)

Some bogus BIOSes jump to 07C0:0000 instead of0000:7C00

REboot: BootkitsRevisited

Bootkit

BasicsBoot process

BIOS

MBR

VBR

BootMGR

Winload

Chain of trust

State of the art

REboot

Conclusion

Samuel Chevet

Boot process

REboot: BootkitsRevisited

Bootkit

BasicsBoot process

BIOS

MBR

VBR

BootMGR

Winload

Chain of trust

State of the art

REboot

Conclusion

Samuel Chevet

Plan

2 BasicsBoot process

BIOSMBRVBRBootMGRWinload

Chain of trust

REboot: BootkitsRevisited

Bootkit

BasicsBoot process

BIOS

MBR

VBR

BootMGR

Winload

Chain of trust

State of the art

REboot

Conclusion

Samuel Chevet

Master Boot Record

Executed in Real modeCopies itself to 0000:0600Searches bootable partition inside partition tableCopies first sector of bootable partition at 0000:7C00Jump to 0000:7C00

REboot: BootkitsRevisited

Bootkit

BasicsBoot process

BIOS

MBR

VBR

BootMGR

Winload

Chain of trust

State of the art

REboot

Conclusion

Samuel Chevet

Boot process

REboot: BootkitsRevisited

Bootkit

BasicsBoot process

BIOS

MBR

VBR

BootMGR

Winload

Chain of trust

State of the art

REboot

Conclusion

Samuel Chevet

Plan

2 BasicsBoot process

BIOSMBRVBRBootMGRWinload

Chain of trust

REboot: BootkitsRevisited

Bootkit

BasicsBoot process

BIOS

MBR

VBR

BootMGR

Winload

Chain of trust

State of the art

REboot

Conclusion

Samuel Chevet

Volume Boot Record

1 sector containing Bios Parameter Block (BPB)BPB structure is completely different from FAT toNTFSBPB uses HiddenSectors field to load InitialProgram Loader (IPL)Jump to it

REboot: BootkitsRevisited

Bootkit

BasicsBoot process

BIOS

MBR

VBR

BootMGR

Winload

Chain of trust

State of the art

REboot

Conclusion

Samuel Chevet

Initial Program Loader

Ability to read FAT32 and NTFSLoad BootMGR at 2000h:0000h (0x20000)Jump to itOr NTLDR for older version (branch is still here ;))

REboot: BootkitsRevisited

Bootkit

BasicsBoot process

BIOS

MBR

VBR

BootMGR

Winload

Chain of trust

State of the art

REboot

Conclusion

Samuel Chevet

Boot process

REboot: BootkitsRevisited

Bootkit

BasicsBoot process

BIOS

MBR

VBR

BootMGR

Winload

Chain of trust

State of the art

REboot

Conclusion

Samuel Chevet

Plan

2 BasicsBoot process

BIOSMBRVBRBootMGRWinload

Chain of trust

REboot: BootkitsRevisited

Bootkit

BasicsBoot process

BIOS

MBR

VBR

BootMGR

Winload

Chain of trust

State of the art

REboot

Conclusion

Samuel Chevet

BootMGR

Map a 32 bit embedded executable to 0x400000Activate protected modeLoad GDT, IDTChecksum of the embedded file

REboot: BootkitsRevisited

Bootkit

BasicsBoot process

BIOS

MBR

VBR

BootMGR

Winload

Chain of trust

State of the art

REboot

Conclusion

Samuel Chevet

BootMGR 32

Ability to use symbols (.pdb) from MicrosoftBmMain(x), BmFwVerifySelfIntegrity(x),ImgpLoadPEImage()Check for hibernation state

Hibernation state TRUELoad Winresume.exe

Hibernation state FALSEMount BCD database, and enumerate boot entries,settings, . . .Change CPU mode to 64 bitsLoad Winload.exe (BmpLaunchBootEntry(x, x, x))

REboot: BootkitsRevisited

Bootkit

BasicsBoot process

BIOS

MBR

VBR

BootMGR

Winload

Chain of trust

State of the art

REboot

Conclusion

Samuel Chevet

Boot process

REboot: BootkitsRevisited

Bootkit

BasicsBoot process

BIOS

MBR

VBR

BootMGR

Winload

Chain of trust

State of the art

REboot

Conclusion

Samuel Chevet

Plan

2 BasicsBoot process

BIOSMBRVBRBootMGRWinload

Chain of trust

REboot: BootkitsRevisited

Bootkit

BasicsBoot process

BIOS

MBR

VBR

BootMGR

Winload

Chain of trust

State of the art

REboot

Conclusion

Samuel Chevet

Winload

Setup minimal 64 bits kernelEnable pagingGet Boot Options (DISABLE_INTEGRITY_CHECKS,TESTSIGNING, . . . )Load BCD entriesFill LOADER_PARAMETER_BLOCKLoad SYSTEM Hives (system32\config\system)Load Ntoskrnl.exe, hal.dll,SERVICE_BOOT_START driversCreate PsLoadedModuleList

REboot: BootkitsRevisited

Bootkit

BasicsBoot process

BIOS

MBR

VBR

BootMGR

Winload

Chain of trust

State of the art

REboot

Conclusion

Samuel Chevet

Winload

GDT EntryCode entry for long modeCode entry for protected modeData entry for protected modeTss for long modeCode entry for real modeData entry for real modeData entry for framebuffer (0x000B8000)

REboot: BootkitsRevisited

Bootkit

BasicsBoot process

BIOS

MBR

VBR

BootMGR

Winload

Chain of trust

State of the art

REboot

Conclusion

Samuel Chevet

Winload

BIOS interruption while in Long modeWinload needs to read / write filesPrint UI, get keyboard input, . . .Winload is able to execute BIOS interruption

REboot: BootkitsRevisited

Bootkit

BasicsBoot process

BIOS

MBR

VBR

BootMGR

Winload

Chain of trust

State of the art

REboot

Conclusion

Samuel Chevet

Boot process

REboot: BootkitsRevisited

Bootkit

BasicsBoot process

BIOS

MBR

VBR

BootMGR

Winload

Chain of trust

State of the art

REboot

Conclusion

Samuel Chevet

Chain of trust

REboot: BootkitsRevisited

Bootkit

Basics

State of the artType of infection

Payload

Problems

REboot

Conclusion

Samuel Chevet

Plan

3 State of the artType of infectionPayloadProblems

REboot: BootkitsRevisited

Bootkit

Basics

State of the artType of infection

Payload

Problems

REboot

Conclusion

Samuel Chevet

State of the art

In 2010, bad guys started to attack 64 bits systemTDL, aka Alureon family of malware

Some BootkitsTDL4TurlagapzxpajCidoxyurnprioxerrovnix. . .

REboot: BootkitsRevisited

Bootkit

Basics

State of the artType of infection

Payload

Problems

REboot

Conclusion

Samuel Chevet

Type of infection

Bootkit techniques (http://www.welivesecurity.com/ c©)

http ://www.welivesecurity.com/

REboot: BootkitsRevisited

Bootkit

Basics

State of the artType of infection

Payload

Problems

REboot

Conclusion

Samuel Chevet

Payload

Keep control during all bootprocess stages untilNtoskrnl.exe loadingFinal malicious payload is injected duringNtoskrnl.exe stage

REboot: BootkitsRevisited

Bootkit

Basics

State of the artType of infection

Payload

Problems

REboot

Conclusion

Samuel Chevet

Payload

BIOS provides interruptionsint 013h (Function : 042h) : Extended Read SectorsHook this interruptionSame technique used in all infection methods

REboot: BootkitsRevisited

Bootkit

Basics

State of the artType of infection

Payload

Problems

REboot

Conclusion

Samuel Chevet

Hook interest

Scan all disk read operations inside hookPatch file in memorySetup new trampoline in next stage(Ex : from MBR -> VBR, VBR -> BootMGR, . . . )Final goal is to reach Ntoskrnl.exe loadingLoad unsigned driversDisable Kernel Protection

Open Source ProjectStonedBootkitVBootkitDreamBoot. . .

REboot: BootkitsRevisited

Bootkit

Basics

State of the artType of infection

Payload

Problems

REboot

Conclusion

Samuel Chevet

Problems

Focused only on executable (VBR, BootMGR_16,BootMGR_32, Windload)Most bootkits rely on code modifications and hooks:

Those are setuped based on patterns matching andhardcoded offsetsRequire to patch the chain of trust

Those techniques are not reliable:Not generic across all Windows versionsTrueCrypt & BitLocker are not supported (oneproject setup two hook layers)Can easily be detected

REboot: BootkitsRevisited

Bootkit

Basics

State of the art

REbootResearch

Real mode to Protectedmode

Protected mode to Longmode

Winload to Ntoskrnl

Payload

Conclusion

Samuel Chevet

Plan

4 REbootResearchReal mode to Protected modeProtected mode to Long modeWinload to NtoskrnlPayload

REboot: BootkitsRevisited

Bootkit

Basics

State of the art

REbootResearch

Real mode to Protectedmode

Protected mode to Longmode

Winload to Ntoskrnl

Payload

Conclusion

Samuel Chevet

Research

Create a proof of concept able to control allbootprocess stages until Windows kernel startupNot based on currently well known techniques

GoalFind a new way to implement bootkits on Windowsusing generic methodsBypass Windows bootprocess chain of trustLoad unsigned drivers at boot

REboot: BootkitsRevisited

Bootkit

Basics

State of the art

REbootResearch

Real mode to Protectedmode

Protected mode to Longmode

Winload to Ntoskrnl

Payload

Conclusion

Samuel Chevet

Ideas

Main problems are CPU mode switches whilebooting:

Real mode (16 bits)Protected mode (32 bits)Long mode (64 bits)

We want to be able to execute arbitrary code at eachstageWithout using hooks or scanning patterns inmemorySo we only use provided processor features!

REboot: BootkitsRevisited

Bootkit

Basics

State of the art

REbootResearch

Real mode to Protectedmode

Protected mode to Longmode

Winload to Ntoskrnl

Payload

Conclusion

Samuel Chevet

Four main steps

1 From Real mode (16 bits) to Protected mode (32 bits)2 From Protected mode to Long mode (64 bits,

Winload)3 From Winload to Ntoskrnl4 Payload execution

REboot: BootkitsRevisited

Bootkit

Basics

State of the art

REbootResearch

Real mode to Protectedmode

Protected mode to Longmode

Winload to Ntoskrnl

Payload

Conclusion

Samuel Chevet

4 Steps

REboot: BootkitsRevisited

Bootkit

Basics

State of the art

REbootResearch

Real mode to Protectedmode

Protected mode to Longmode

Winload to Ntoskrnl

Payload

Conclusion

Samuel Chevet

Plan

4 REbootResearchReal mode to Protected modeProtected mode to Long modeWinload to NtoskrnlPayload

REboot: BootkitsRevisited

Bootkit

Basics

State of the art

REbootResearch

Real mode to Protectedmode

Protected mode to Longmode

Winload to Ntoskrnl

Payload

Conclusion

Samuel Chevet

Virtual 8086 mode

Virtual 8086 mode is a sub-mode of Protected modeV86 allows to execute 8086 code under protectedmodeNTVDMVirtual machine (VM) bit in the EFLAGS (bit #17)register is setWe need only one taskpopf does not work, use iret or 386 TSSTrap on privileged instruction, like lgdt

REboot: BootkitsRevisited

Bootkit

Basics

State of the art

REbootResearch

Real mode to Protectedmode

Protected mode to Longmode

Winload to Ntoskrnl

Payload

Conclusion

Samuel Chevet

Virtual 8086 mode

Problem encounteredAt first we used an I/O privilege level (IOPL) equalto 3Only exceptions during privilegied instructionsTPM BIOS interruption (0x1A) setup a protectedmodeFalse positive detection of BootMGR

REboot: BootkitsRevisited

Bootkit

Basics

State of the art

REbootResearch

Real mode to Protectedmode

Protected mode to Longmode

Winload to Ntoskrnl

Payload

Conclusion

Samuel Chevet

Virtual 8086 mode

SolutionUse IOPL equal to 1When an interruption is trying to be executed

1 We setup back real mode CPU2 Execute it3 We go back to v8086 mode

REboot: BootkitsRevisited

Bootkit

Basics

State of the art

REbootResearch

Real mode to Protectedmode

Protected mode to Longmode

Winload to Ntoskrnl

Payload

Conclusion

Samuel Chevet

Virtual 8086 mode

Step by StepSetup Protected modeLoad original MBRSetup and enable VM 86 modeJump to original MBRManage all exceptionsGP Handler executed during lgdt instruction

REboot: BootkitsRevisited

Bootkit

Basics

State of the art

REbootResearch

Real mode to Protectedmode

Protected mode to Longmode

Winload to Ntoskrnl

Payload

Conclusion

Samuel Chevet

Real mode to Protected mode

First step has been solved using V8086 mode

REboot: BootkitsRevisited

Bootkit

Basics

State of the art

REbootResearch

Real mode to Protectedmode

Protected mode to Longmode

Winload to Ntoskrnl

Payload

Conclusion

Samuel Chevet

Plan

4 REbootResearchReal mode to Protected modeProtected mode to Long modeWinload to NtoskrnlPayload

REboot: BootkitsRevisited

Bootkit

Basics

State of the art

REbootResearch

Real mode to Protectedmode

Protected mode to Longmode

Winload to Ntoskrnl

Payload

Conclusion

Samuel Chevet

Protected mode to Long mode

With V8086 mode, we control until BootMGR_32BootMGR_32 must :

Prepare Long mode in case of 64 bits kernelSetup new GDT and IDTEnable paging

This new IDT must be placed on an allocated pageAll these operations are carried out byImgArchPcatStartBootApplication() function

REboot: BootkitsRevisited

Bootkit

Basics

State of the art

REbootResearch

Real mode to Protectedmode

Protected mode to Longmode

Winload to Ntoskrnl

Payload

Conclusion

Samuel Chevet

Protected mode to Long mode

ImgArchPcatStartBootApplication()Setup a page for new GDT and IDTUse sidt instruction to get current IDT entries(created by BootMGR_16) and copy them to the newoneTest IMAGE_FILE_HEADER->Machine for starting32 bits application or 64 bits

ImgPcatStart64BitApplication()Case for 64 bits applicationReset all new IDT entries because it is invalid forLong mode

REboot: BootkitsRevisited

Bootkit

Basics

State of the art

REbootResearch

Real mode to Protectedmode

Protected mode to Longmode

Winload to Ntoskrnl

Payload

Conclusion

Samuel Chevet

Protected mode to Long mode

When in protected mode we can :Use Debug registers (dr0 . . . dr3)Setup Debug Interrupt (0x1)We control until Winload execution

REboot: BootkitsRevisited

Bootkit

Basics

State of the art

REbootResearch

Real mode to Protectedmode

Protected mode to Longmode

Winload to Ntoskrnl

Payload

Conclusion

Samuel Chevet

Protected mode to Long mode

REboot: BootkitsRevisited

Bootkit

Basics

State of the art

REbootResearch

Real mode to Protectedmode

Protected mode to Longmode

Winload to Ntoskrnl

Payload

Conclusion

Samuel Chevet

Protected mode to Long mode

Second step has been solved using debug registers

REboot: BootkitsRevisited

Bootkit

Basics

State of the art

REbootResearch

Real mode to Protectedmode

Protected mode to Longmode

Winload to Ntoskrnl

Payload

Conclusion

Samuel Chevet

Plan

4 REbootResearchReal mode to Protected modeProtected mode to Long modeWinload to NtoskrnlPayload

REboot: BootkitsRevisited

Bootkit

Basics

State of the art

REbootResearch

Real mode to Protectedmode

Protected mode to Longmode

Winload to Ntoskrnl

Payload

Conclusion

Samuel Chevet

Winload to Ntoskrnl

With debug registers, we control until WinloadWinload starts with an empty IDT_64

BlpArchInstallTrapVectors()Retrieve IDTR with ArchGetIdtRegister() and setupnew Long mode entries

We can setup a DRX on access on these entries beforeswitching from Protected mode to Long mode

REboot: BootkitsRevisited

Bootkit

Basics

State of the art

REbootResearch

Real mode to Protectedmode

Protected mode to Longmode

Winload to Ntoskrnl

Payload

Conclusion

Samuel Chevet

Winload to Ntoskrnl

REboot: BootkitsRevisited

Bootkit

Basics

State of the art

REbootResearch

Real mode to Protectedmode

Protected mode to Longmode

Winload to Ntoskrnl

Payload

Conclusion

Samuel Chevet

Winload to Ntoskrnl

Now we can control execution "inside" WinloadWe want to monitor the transition between Winloadand NtosknrlWinload will setup a new GDT and IDT beforejumping to kernelWe can follow these operations by tracing privilegedinstructionsSo we run Winload’s code at ring 1 privilege (DPL=1)

Why ring 1?Winload sections are in paged area

Intel 64 and IA-32 Architectures Developer’s Manual: Vol. 3A 4-38

REboot: BootkitsRevisited

Bootkit

Basics

State of the art

REbootResearch

Real mode to Protectedmode

Protected mode to Longmode

Winload to Ntoskrnl

Payload

Conclusion

Samuel Chevet

Ring 1

Setup new Code / Data segment with DPL = 1Setup General Protection fault handlerFill rsp0 field inside TSS_64

GP HandlerCheck where the fault occuredCheck what privileged instruction occuredCopy it and execute it somewhere elseOr "emulate" it

REboot: BootkitsRevisited

Bootkit

Basics

State of the art

REbootResearch

Real mode to Protectedmode

Protected mode to Longmode

Winload to Ntoskrnl

Payload

Conclusion

Samuel Chevet

Ring 1

Examplemov ds, axmov rax, cr3jmp far . . .. . .

REboot: BootkitsRevisited

Bootkit

Basics

State of the art

REbootResearch

Real mode to Protectedmode

Protected mode to Longmode

Winload to Ntoskrnl

Payload

Conclusion

Samuel Chevet

Ring 1 : Special cases

mov ds, axIn PcatX64SuCallbackWinload wants to update data segment to perform aBIOS interrupt (swich from long mode to real mode)At this point, restore ring0 to avoid any problemWait come back from real mode (jmp far10h:343D31h)

jmp far XX:YYYYFault occurs because DPL != RPLUpdate cs, ss and ip before iretq

mov ss, axHappen just after jmp:farAvoid instruction

REboot: BootkitsRevisited

Bootkit

Basics

State of the art

REbootResearch

Real mode to Protectedmode

Protected mode to Longmode

Winload to Ntoskrnl

Payload

Conclusion

Samuel Chevet

Winload to Ntoskrnl

All other cases can be copied and executed fromsomewhere elseLast case is lgdt fword ptr [rax]In function : OslArchTransferToKernelJust before jumping into Ntoskrnl.exeFirst parameter of KiSystemStartup() isLOADER_PARAMETER_BLOCK+0x10 : _LDR_DATA_TABLE_ENTRY (boot driver)

REboot: BootkitsRevisited

Bootkit

Basics

State of the art

REbootResearch

Real mode to Protectedmode

Protected mode to Longmode

Winload to Ntoskrnl

Payload

Conclusion

Samuel Chevet

Winload to Ntoskrnl

Third step has been solved using ring protection

REboot: BootkitsRevisited

Bootkit

Basics

State of the art

REbootResearch

Real mode to Protectedmode

Protected mode to Longmode

Winload to Ntoskrnl

Payload

Conclusion

Samuel Chevet

Plan

4 REbootResearchReal mode to Protected modeProtected mode to Long modeWinload to NtoskrnlPayload

REboot: BootkitsRevisited

Bootkit

Basics

State of the art

REbootResearch

Real mode to Protectedmode

Protected mode to Longmode

Winload to Ntoskrnl

Payload

Conclusion

Samuel Chevet

Just before Ntoskrnl.exe

Inject our own driver in the PsLoadModuleListWe have access to ntoksrnl’s APIsBut we cannot use it because kernel is not initialisedSo replace EntryPoint of known driversBut most of driver’s entry point are called fromhal.dll, kernel is still not fully initialisedSo replace export function of kdcom.dll(KdDebuggerInitialize1)

REboot: BootkitsRevisited

Bootkit

Basics

State of the art

REbootResearch

Real mode to Protectedmode

Protected mode to Longmode

Winload to Ntoskrnl

Payload

Conclusion

Samuel Chevet

Payload

We do not want to inject specific payloadGoal is loading unsigned driversUse undocumented method to avoid signaturechecking

Undocumented methodIoCreateDriver(PUNICODE_STRING DriverName,PDRIVER_INITIALIZE InitializationFunction)Function exported by Ntoskrnl.exe in order to createa driver objectDriverName can be null

REboot: BootkitsRevisited

Bootkit

Basics

State of the art

REbootResearch

Real mode to Protectedmode

Protected mode to Longmode

Winload to Ntoskrnl

Payload

Conclusion

Samuel Chevet

Payload

We do not want to inject specific payloadGoal is loading unsigned driversUse undocumented method to avoid signaturechecking

Undocumented methodIoCreateDriver(PUNICODE_STRING DriverName,PDRIVER_INITIALIZE InitializationFunction)Function exported by Ntoskrnl.exe in order to createa driver objectDriverName can be null

REboot: BootkitsRevisited

Bootkit

Basics

State of the art

REbootResearch

Real mode to Protectedmode

Protected mode to Longmode

Winload to Ntoskrnl

Payload

Conclusion

Samuel Chevet

Payload

InitializationFunctionOpen and Read (PE) driver fileMap sections in memoryResolve importsFix image relocationsFill information of DRIVER_OBJECTCall entry point

REboot: BootkitsRevisited

Bootkit

Basics

State of the art

REbootResearch

Real mode to Protectedmode

Protected mode to Longmode

Winload to Ntoskrnl

Payload

Conclusion

Samuel Chevet

Driver example

Patch msv1_0!MsvpPasswordValidate from LSASSprocessEscalate privileges of any cmd.exe commandChange behavior of CTRL+ALT+DEL. . .

REboot: BootkitsRevisited

Bootkit

Basics

State of the art

REboot

Conclusion

Samuel Chevet

Plan

5 Conclusion

REboot: BootkitsRevisited

Bootkit

Basics

State of the art

REboot

Conclusion

Samuel Chevet

Demo

Demo time !

REboot: BootkitsRevisited

Bootkit

Basics

State of the art

REboot

Conclusion

Samuel Chevet

TODO

Still work to be doneImplementing UEFI (without SecureBoot)More work to do with BitLocker or TrueCrypt:Extract passphrase at boot

REboot: BootkitsRevisited

Bootkit

Basics

State of the art

REboot

Conclusion

Samuel Chevet

Conclusion

Real interest to use bootkit techniques, for loadingunsigned driversREBoot uses no memory modifications!Chain of trust defeatedWorks on all 64 bits Windows versionsVirtual environments or emulated environmentsPhysical machines with BIOS or UEFI legacyDoes not work if UEFI Secureboot is present

REboot: BootkitsRevisited

Bootkit

Basics

State of the art

REboot

Conclusion

Samuel Chevet

Questions ?

Thank you for your attention

BootkitBasicsBoot processChain of trust

State of the artType of infectionPayloadProblems

REbootResearchReal mode to Protected modeProtected mode to Long modeWinload to NtoskrnlPayload

Conclusion