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先简单介绍下PatchGuard ，摘自百度百科
//Disable PatchGuard - the easy/lazy way. //for Vista SP2 & Windows 7 (X64) // //by Fyyre (thank you Roxaz for helping me to test) //http://fyyre.l2-fashion.de/ //http://twitter.com/Fyyre last update: 19/03/2011 This txt file provides a general overview/outline for bypassing signature validation of critical system files (ntoskrnl, mainly) during the Vista/Win 7 boot phase. It is documentation of the steps taken from start to finish, to reach the desired goal of removing kernel patch protection "PatchGuard" without use of a driver. We will call this the ‘lazy/easy‘ way to kill PatchGuard. We cannot modify ntoskrnl without winload taking up issue... winload.exe is the Windows loader for Vista & Windows 7. Along with this, he makes some verification of digital signatures and checking to make sure the files have not been modified. If modification of ntoskrnl is detected, the result is winload *refusing* to boot Windows and launching a WinPE looking "Recovery Mode". PART I { additional }: new way for patch of winload.exe Function ImgpValidateImageHash - signature we locate: 8B C3 49 8B 5B 20 49 8B 73 28 49 8B 7B 30 4D 8B -- you may play with this one to make him smaller. as for this patching, use of dUP2... size of not a concern. First bytes replaced with xor eax, eax (STATUS_SUCCESS) .. all validations successful. PART I: disassembly and modification of winload.exe Starting from OslpMain, after loading the System registry hives(registry)... occurs a call to OslInitializeCodeIntegrity: .text:00000000004016C3 call OslpLoadSystemHive .text:00000000004016C3 .text:00000000004016C8 cmp eax, ebx .text:00000000004016CA mov edi, eax .text:00000000004016CC jl loc_401A08 .text:00000000004016CC .text:00000000004016D2 mov ecx, ebp .text:00000000004016D4 call OslInitializeCodeIntegrity <<-- =( .text:00000000004057E8 OslInitializeCodeIntegrity proc near original code -->> We will replace four bytes here: 48 8B C4 53 .text:00000000004057E8 mov rax, rsp .text:00000000004057EB push rbx .text:00000000004057EC push rbp with: 0B0h, 01h, 0C3h, 090h ... which produce: mov al, 1 ret nop Save as winload.exe as osloader.exe (or whatever..) & correct PE checksum (LordPE and/or CFF_Explorer will do). Copy osloader.exe to \Windows\System32 PART II - new BCD entry: bcdedit /copy {current} /d "PatchGuard Disabled" "The entry was successfully copied to {01234567-89ab-cdef-00ff-fff000ffffff}" <<-- GUID of new entry. each is different! bcdedit /timeout 10 <<-- number of seconds to show boot menu. bcdedit /set {01234567-89ab-cdef-00ff-fff000ffffff} nointegritychecks 1 <<-- no validation of winload bcdedit /set {01234567-89ab-cdef-00ff-fff000ffffff} recoveryenabled 0 <<-- optional... i dislike this feature, therefore disable. bcdedit /set {01234567-89ab-cdef-00ff-fff000ffffff} path \Windows\system32\osloader.exe bcdedit /set {01234567-89ab-cdef-00ff-fff000ffffff} kernel ntkrnlmp.exe (name of modified ntos... =)) Part III: Skip Initialization of PatchGuard - - (driver not required) As for this .txt, and PatchGuard... we are concerned with one function KiInitializePatchGuard(*1) which is called by KiFilterFiberContext. KiInitializePatchGuard is a very large function located in the INIT section of ntoskrnl, you can easily locate him via two calls from KiFilterFiberContext, by examination xrefs to exported dword InitSafeBootMode, searching for db 20h dup(90h) + db 044h ... or 48 81 EC 58 0F 00 00 to name a few... PatchGuard does not initialize if we boot into safe mode. So to disable we just patch one conditional jxx KiInitializePatchGuard: original code -->> INIT:000000014055D359 sub rsp, 0F58h INIT:000000014055D360 xor edi, edi INIT:000000014055D362 cmp cs:InitSafeBootMode, edi INIT:000000014055D368 jz short loc_14055D371 INIT:000000014055D368 INIT:000000014055D36A mov al, 1 INIT:000000014055D36C jmp loc_1405600D9 modified code -->> INIT:000000014055D359 sub rsp, 0F58h INIT:000000014055D360 xor edi, edi INIT:000000014055D362 cmp cs:InitSafeBootMode, edi INIT:000000014055D368 nop INIT:000000014055D369 nop INIT:000000014055D36A mov al, 1 INIT:000000014055D36C jmp loc_1405600D9 <<-- to end of KiInitializePatchGuard and back to KiFilterFiberContext... and important detail: The first jxx in KiInitializePatchGuard must not be taken & al == 1. When we return to KiFilterFiberContext, the jxx must be taken, and EBX must not be xor‘d ... (unless enjoy BSOD). INIT:0000000140567110 loc_140567110: INIT:0000000140567110 test al, al INIT:0000000140567112 jnz short loc_140567116 INIT:0000000140567112 INIT:0000000140567114 INIT:0000000140567114 loc_140567114: INIT:0000000140567114 xor ebx, ebx <<-- bad INIT:0000000140567114 Anyways... nop the first jxx in KiInitializePatchGuard... save modified ntoskrnl.exe with a different name (i.e. ntkrnlmp.exe) ... fix checksum (PE header). Then copy your modified kernel to \Windows\system32 -- with bcdedit -->> bcdedit /set {guid-of-new-entry} kernel ntkrnlmp.exe When you reboot the system, loading your modified kernel should be a success... He will load without PatchGuard initializing, which will allow you to once again play in kernel mode without receiving BSOD as result... This could be worked into mbr bootkit code as well... this is beyond the scope of our intention. -Fyyre references: *1: Bypassing PatchGuard on Windows x64, by Skywing 12/1/2005
根据文章我们先将winload.exe放入ida中，根据文章中定位到OslpMain函数（这里我已经导入了winload.exe的符号表）
.text:00000000004016BE 4C 8B C6 mov r8, rsi .text:00000000004016C1 8B CD mov ecx, ebp .text:00000000004016C3 E8 94 04 00 00 call OslpLoadSystemHive //加载注册表单元 .text:00000000004016C8 3B C3 cmp eax, ebx .text:00000000004016CA 8B F8 mov edi, eax .text:00000000004016CC 0F 8C 36 03 00 00 jl loc_401A08 .text:00000000004016D2 8B CD mov ecx, ebp .text:00000000004016D4 E8 03 41 00 00 call OslInitializeCodeIntegrity
发现加载了注册表单元之后调用了OslInitializeCodeIntegrity函数，我们继续跟进
原来的代码
.text:00000000004057DC OslInitializeCodeIntegrity proc near .text:00000000004057DC 48 8B C4 mov rax, rsp .text:00000000004057DF 53 push rbx .text:00000000004057E0 55 push rbp .text:00000000004057E1 57 push rdi .text:00000000004057E2 41 54 push r12
我们要做的就是替换掉最开始的一个字节，让整个函数不再向下执行，因为在接下来会调用BlImgQueryCodeIntegrityBootOptions，因为BlImgQueryCodeIntegrityBootOptioins会校验Ntoskrnl.exe的数字签名的有效性，如果非法的话就拒绝加载Ntoskrnl.exe，我们需要绕过这个函数
.text:00000000004057FB 48 8D 50 10 lea rdx, [rax+10h] .text:00000000004057FF 4C 89 68 20 mov [rax+20h], r13 .text:0000000000405803 49 8B FD mov rdi, r13 .text:0000000000405806 4C 89 68 C8 mov [rax-38h], r13 .text:000000000040580A E8 21 B6 02 00 call BlImgQueryCodeIntegrityBootOptions
所以在OllInitializeCodeIntegrity 函数开始部分就直接返回，跳过BlImgQueryCodeIntegrityBootOptioins
将 48 8B C4 mov rax, rsp 替换成 B0 01 mov al , 1 C3 ret
接下来就是Ntoskrnl.exe了
根据文章中的说明，定位到KiFilterFiberContext函数，发现对KiInitializePatchGuard的调用
INIT:0000000140577106 8B D1 mov edx, ecx INIT:0000000140577108 41 8B C9 mov ecx, r9d INIT:000000014057710B E8 30 62 FF FF call KiInitializePatchGuard //这里是我自己重命名了，本来的只是一个地址，符号表中没有
NIT:000000014056D360 33 FF xor edi, edi INIT:000000014056D362 39 3D 88 21 D1 FF cmp cs:InitSafeBootMode, edi //检测是否以安全模式启动，如果以安全模式启动PatchGuard就不会被初始化 INIT:000000014056D368 74 07 jz short loc_14056D371 //这里的跳转才是对PatchGuard就行正在初始化，我们将其nop掉 INIT:000000014056D36A B0 01 mov al, 1
INIT:000000014056D36C E9 68 2D 00 00 jmp loc_1405700D9 //直接跳转到KiInitilizePatchGuard函数的结尾，不初始化
然后就是保存，然后在启动项中添加我们自己的“内核”。
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原文地址：http://www.cnblogs.com/lanrenxinxin/p/4448603.html
