DNF 驱动对内存读取的过滤分析
下面是分析tessafe.sys对 NtReadVirtualMemory调用的过滤处理方法，以及应对办法。一、运行DNF后 打开windbg 定位到 NtReadVirtualMemory 函数位置，内核汇编代码如下：
nt!NtReadVirtualMemory:
805b52b8 b808d316b3 mov eax,0B316D308h;TesSafe.sys hook位置
805b52bd ffe0 jmp eax
805b52bf e8dc78f8ff call nt!_SEH_prolog (8053cba0)
805b52c4 64a124010000 mov eax,dword ptr fs:
805b52ca 8bf8 mov edi,eax
805b52cc 8a8740010000 mov al,byte ptr
805b52d2 8845e0 mov byte ptr ,al
805b52d5 8b7514 mov esi,dword ptr
805b52d8 84c0 test al,al
805b52da 7466 je nt!NtReadVirtualMemory+0x8a (805b5342)
805b52dc 8b450c mov eax,dword ptr
805b52df 8d1430 lea edx,
805b52e2 3bd0 cmp edx,eax
定位到0B316D308位置，此部分代码就是tessafe.sys的过滤函数。下面是对这些会汇编代码的分析，有点乱
b316d308 8bff mov edi,edi
b316d30a 55 push ebp
b316d30b 8bec mov ebp,esp
b316d30d 81ec00010000 sub esp,100h
b316d313 60 pushad
b316d314 9c pushfd
b316d315 b8206f17b3 mov eax,0B3176F20h ;ecx = 0B3176F20h
b316d31a 33c9 xor ecx,ecx ;ecx =0
b316d31c 41 inc ecx ;ecx = 1
b316d31d f00fc108 lock xadd dword ptr ,ecx ; += 1
b316d321 ff154c4017b3 call dword ptr ds: ;call nt!PsGetCurrentProcess
b316d327 8945f8 mov dword ptr ,eax ;=current EPROCESS
b316d32a 6a00 push 0 ; push 0
b316d32c 8d45fc lea eax,
b316d32f 50 push eax ;push ptr
b316d330 6a00 push 0 ;push 0
b316d332 a15c4117b3 mov eax,dword ptr ds: ;eax = =805649b8
b316d337 ff30 push dword ptr ;push 805649b8
b316d339 6800040000 push 400h ;push 0x400
b316d33e ff7508 push dword ptr ;push 目标进程 ProcessHandle
b316d341 ff159c4017b3 call dword ptr ds: ;call ObReferenceObjectByHandle
b316d347 8945f4 mov dword ptr ,eax ;判断函数调用是否成功
b316d34a 837df400 cmp dword ptr ,0
b316d34e 7d02 jge b316d352
b316d350 eb65 jmp b316d3b7 ;不成功跳转
b316d352 8b4dfc mov ecx,dword ptr ;ecx = 目标进程句柄信息
b316d355 ff15584117b3 call dword ptr ds: ;call ObfDereferenceObject 撤销对象的引用计数
b316d35b 8b45fc mov eax,dword ptr ;eax = 目标的句柄信息
b316d35e 3b45f8 cmp eax,dword ptr ;比较目标进程是否是本进程
b316d361 7502 jne b316d365 ;不能，继续判断
b316d363 eb52 jmp b316d3b7 ;相等不进行拦截
b316d365 6a04 push 4 ;push 4
b316d367 ff75fc push dword ptr ;push 目标进程句柄信息
b316d36a e8c3fdffff call b316d132 ;判断目标进程是否是DNF进程
b316d36f 0fb6c0 movzx eax,al
b316d372 85c0 test eax,eax
b316d374 7502 jne b316d378
b316d376 eb3f jmp b316d3b7 ;目标进程不是DNF进程，不进行拦截
b316d378 6a04 push 4 ;push 4
b316d37a ff75f8 push dword ptr ;当前进程eprocess
b316d37d e8f0fcffff call b316d072 ;比较当前进程是否在白名单中
b316d382 0fb6c0 movzx eax,al
b316d385 85c0 test eax,eax
b316d387 7402 je b316d38b ;在白名单中，继续判断
b316d389 eb2c jmp b316d3b7 ;不再则跳转，将屏蔽此次调用
b316d38b 6a04 push 4 ;push 4
b316d38d ff75f8 push dword ptr ;push 目标进程结构
b316d390 e81bfdffff call b316d0b0 ;判断是否在另外一份白名单中
b316d395 0fb6c0 movzx eax,al
b316d398 85c0 test eax,eax
b316d39a 7402 je b316d39e ;在第二份白名单中
b316d39c eb19 jmp b316d3b7 ;不在第二份白名单中，将屏蔽此次调用
b316d39e b8206f17b3 mov eax,0B3176F20h ;
b316d3a3 83c9ff or ecx,0FFFFFFFFh
b316d3a6 f00fc108 lock xadd dword ptr ,ecx ; += -1
b316d3aa 9d popfd
b316d3ab 61 popad
b316d3ac 8be5 mov esp,ebp ;
b316d3ae 5d pop ebp
b316d3af b80d0000c0 mov eax,0C000000Dh ;置返回错误代码
b316d3b4 c21400 ret 14h ;不在白名单中，调用失败
b316d3b7 b8206f17b3 mov eax,0B3176F20h ; += -1
b316d3bc 83c9ff or ecx,0FFFFFFFFh
b316d3bf f00fc108 lock xadd dword ptr ,ecx
b316d3c3 9d popfd
b316d3c4 61 popad
b316d3c5 8be5 mov esp,ebp
b316d3c7 5d pop ebp
b316d3c8 6a1c push 1Ch
b316d3ca 68f0ae4d80 push offset nt!MmClaimParameterAdjustDownTime+0x90 (804daef0)
b316d3cf 90 nop
b316d3d0 90 nop
b316d3d1 90 nop
b316d3d2 90 nop
b316d3d3 90 nop
b316d3d4 90 nop
b316d3d5 90 nop
b316d3d6 90 nop
b316d3d7 90 nop
b316d3d8 ff253c6e17b3 jmp dword ptr ds: ；跳转到
b316d3de cc int 3
b316d3df cc int 3
//==============================================================================
b316d132如果为DNF进程返回0 否则返回1
b316d132 8bff mov edi,edi
b316d134 55 push ebp
b316d135 8bec mov ebp,esp
b316d137 51 push ecx
b316d138 53 push ebx
b316d139 56 push esi
b316d13a c645ff00 mov byte ptr ,0 ; = 0;
b316d13e 32db xor bl,bl ;bl = 0;
b316d140 ff15084017b3 call dword ptr ds: ;call KeGetCurrentIrql 得到IRQ级别
b316d146 3c02 cmp al,2 ;判断是否在 DISPATCH_LEVEL级别
b316d148 bebc7117b3 mov esi,0B31771BCh ;esi = 0B31771BCh
b316d14d 8bce mov ecx,esi ;ecx = 0B31771BCh
b316d14f 720a jb b316d15b ;小于DISPATCH_LEVEL级别 跳转
b316d151 ff15784017b3 call dword ptr ds: ; call KefAcquireSpinLockAtDpcLevel
b316d157 fec3 inc bl ;b1++
b316d159 eb09 jmp b316d164
b316d15b ff150c4017b3 call dword ptr ds: ;call KfAcquireSpinLock
b316d161 8845fe mov byte ptr ,al
b316d164 a1c07117b3 mov eax,dword ptr ds: ;eax = =88c1dee4
b316d169 b9c07117b3 mov ecx,0B31771C0h ;ecx = 0B31771C0h
b316d16e eb0a jmp b316d17a
b316d170 8b50cc mov edx,dword ptr ;取得链表节点对应eprocess
b316d173 3b5508 cmp edx,dword ptr ;与目标进程比较
b316d176 7408 je b316d180 ;相等 跳转
b316d178 8b00 mov eax,dword ptr
b316d17a 3bc1 cmp eax,ecx ;比较 == 0B31771C0h 比较是否到链表尾部
b316d17c 75f2 jne b316d170 ;不等进行进程eprocess 比较
b316d17e eb0c jmp b316d18c ;到链表结尾，跳转
b316d180 8b4d0c mov ecx,dword ptr ;ECX=4
b316d183 8548e0 test dword ptr ,ecx ;0x7ff&0x04 >0
b316d186 7404 je b316d18c
b316d188 c645ff01 mov byte ptr ,1 ;=1
b316d18c 84db test bl,bl ;b1 ==0
b316d18e 8bce mov ecx,esi ;ecx=0B31771BCh
b316d190 7408 je b316d19a ;=0 跳转
b316d192 ff15744017b3 call dword ptr ds:
b316d198 eb09 jmp b316d1a3
b316d19a 8a55fe mov dl,byte ptr ;dl =irql级别
b316d19d ff15104017b3 call dword ptr ds: ;call KfReleaseSpinLock
b316d1a3 8a45ff mov al,byte ptr a1 = 1
b316d1a6 5e pop esi
b316d1a7 5b pop ebx
b316d1a8 c9 leave
b316d1a9 c20800 ret 8
//=====================================================================
b316d072判断是否在白名单1中
b316d072 8bff mov edi,edi
b316d074 55 push ebp
b316d075 8bec mov ebp,esp
b316d077 8b0da87117b3 mov ecx,dword ptr ;ecx = = 89a3442c
b316d07d baa87117b3 mov edx,offset TesSafe+0xd1a8 (b31771a8) ;edx = b31771a8
b316d082 32c0 xor al,al ;a1 = 0
b316d084 3bca cmp ecx,edx ;判断是否是空链表
b316d086 741f je TesSafe+0x30a7 (b316d0a7) ;空链表跳转
b316d088 56 push esi
b316d089 8b7508 mov esi,dword ptr ;esi=当前进程EPROCESS
b316d08c 3b71dc cmp esi,dword ptr ;比较目标进程是否在白名单中
b316d08f 7408 je TesSafe+0x3099 (b316d099) ;相等则跳转
b316d091 8b09 mov ecx,dword ptr ；取下一个节点
b316d093 3bca cmp ecx,edx ;判断是否到链表结尾
b316d095 75f2 jne TesSafe+0x3089 (b316d089) ;不到则继续判断
b316d097 eb0d jmp TesSafe+0x30a6 (b316d0a6) ;到链表结尾，而且没有在白名单中匹配
b316d099 8b550c mov edx,dword ptr ;edx =4
b316d09c ff41fc inc dword ptr ;++
b316d09f 8551e4 test dword ptr ,edx ; 是否等于4 不等于4 则屏蔽
b316d0a2 7402 je TesSafe+0x30a6 (b316d0a6)
b316d0a4 b001 mov al,1
b316d0a6 5e pop esi
b316d0a7 5d pop ebp
b316d0a8 c20800 ret 8
在windbg 查看
lkd> dd 89a3442c-24
89a344088a5aa288 00000500 000fffff e8710e72
89a3441874737953 00006d65 00000000 00000000
89a3442800000000 88afc274 b31771a8 005c003f
89a344380a090007 68734c4b 89d5c8f0 89ad8778
89a34448896ec690 00000000 00000000 897e47a8
89a3445889d5dbf0 89ad87dc 00010000 00000001
89a344680001502b 00000000 e3a67220 00000008
89a3447800000000 00000000 0a080009 e174754d
lkd> !process 8a5aa288 0
Unable to read selector for PCR for processor 0
PROCESS 8a5aa288SessionId: noneCid: 0004 Peb: 00000000ParentCid: 0000
DirBase: 0aed8020ObjectTable: e1002e38HandleCount: 474.
Image: System
下面我找到白名单进程
System
smss.exe
csrss.exe
SERVICES.EXE
LSASS.EXE
SVCHOST.EXE
//===========================
判断是否在白名单2中
b2a510b0 8bff mov edi,edi
b2a510b2 55 push ebp
b2a510b3 8bec mov ebp,esp
b2a510b5 51 push ecx
b2a510b6 53 push ebx
b2a510b7 56 push esi
b2a510b8 c645ff00 mov byte ptr ,0 ; = 0
b2a510bc 32db xor bl,bl ;b1 = 0
b2a510be ff150880a5b2 call dword ptr call KeGetCurrentIrql
b2a510c4 3c02 cmp al,2 比较当前IRQL级别是否为DISPATCH_LEVEL级别
b2a510c6 beb8b1a5b2 mov esi,offset TesSafe+0xd1b8 (b2a5b1b8) esi = b2a5b1b8
b2a510cb 8bce mov ecx,esi ecx = b2a5b1b8
b2a510cd 720a jb TesSafe+0x30d9 (b2a510d9) ;小于DISPATCH_LEVEL级别 跳转
b2a510cf ff157880a5b2 call dword ptr ;call Ke386QueryIoAccessMap
b2a510d5 fec3 inc bl ;b1 = 1
b2a510d7 eb09 jmp TesSafe+0x30e2 (b2a510e2)
b2a510d9 ff150c80a5b2 call dword ptr ;call KfAcquireSpinLock
b2a510df 8845fe mov byte ptr ,al 保存当前IRQL
b2a510e2 a1b0b1a5b2 mov eax,dword ptr ;eax = =8993e02c
b2a510e7 b9b0b1a5b2 mov ecx,offset TesSafe+0xd1b0 (b2a5b1b0) ;ecx = b2a5b1b0
b2a510ec eb0a jmp TesSafe+0x30f8 (b2a510f8)
b2a510ee 8b50dc mov edx,dword ptr
b2a510f1 3b5508 cmp edx,dword ptr ;白名单判断
b2a510f4 7408 je TesSafe+0x30fe (b2a510fe)
b2a510f6 8b00 mov eax,dword ptr
b2a510f8 3bc1 cmp eax,ecx
b2a510fa 75f2 jne TesSafe+0x30ee (b2a510ee)
b2a510fc eb0f jmp TesSafe+0x310d (b2a5110d)
b2a510fe 8b4d0c mov ecx,dword ptr
b2a51101 ff40fc inc dword ptr
b2a51104 8548e4 test dword ptr ,ecx
b2a51107 7404 je TesSafe+0x310d (b2a5110d)
b2a51109 c645ff01 mov byte ptr ,1
b2a5110d 84db test bl,bl
b2a5110f 8bce mov ecx,esi
b2a51111 7408 je TesSafe+0x311b (b2a5111b)
b2a51113 ff157480a5b2 call dword ptr
b2a51119 eb09 jmp TesSafe+0x3124 (b2a51124)
b2a5111b 8a55fe mov dl,byte ptr
b2a5111e ff151080a5b2 call dword ptr
b2a51124 8a45ff mov al,byte ptr
b2a51127 5e pop esi
b2a51128 5b pop ebx
b2a51129 c9 leave
b2a5112a c20800 ret 8
TXPlatform.exe
QQ.exe
**** Hidden Message ***** 在学驱动看看 55447当前长度: 5 字 牛B啊楼主！ ddddddddddddddddddddddddddd 是打发士大夫撒大法师的 驱动对内存读取的过滤分 :(看看学学 回复 1# oowoo
多写几个吧 谢谢咯 回复 1# oowoo
看看隐藏的是什么东东
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