Question

只有当嵌套结构中的字符串作为参数与我选择的特定模式匹配时，我才试图在函数内点击断点，如下所示：

bp `main.c:2236` ".block { .if ( $spat(\"@@(stNames->NameComponent.Buffer)\", \"*ab*\" )){.echo \"BKP HIT! \"; .printf \"%mu str\n\",> @@(NameInfo->FinalComponent.Buffer); } .else {.echo \"NO HIT \"; .printf \"%mu str:\n\", @@(stNames->NameComponent.Buffer); gc;} } "

在已经解析参数符号之后，此断点设置在函数的开头。它表现得很奇怪，即使$ spat中的模式不匹配，有时它也会一直受到攻击，即使模式匹配，它有时也不会被击中。

我也试过this没有运气，因为在这种嵌套结构的情况下我无法找到使用poi（）命令的方法。 Snippet bellow：

bp Kernel32!CreateFileW ".printf \"%mu\\n\", poi(esp+4); as /mu ${/v:FileName} poi(esp+4); .block{.if $spat(\"${FileName}\", \"*target*\") {.echo Hit} .else {.echo Not Yet;g;}}"

Answer 1

表达式\"@@(stNames->NameComponent.Buffer)\"可能does not evaluate to a quoted string独立评估

当写条件打破尽可能小的条件时
并将它们放在一个txt文件中，并将脚本文件提供给断点
就像bp：32 " $$>a< c:\\windscrypted.txt一样，更容易参与

如果问题是独立的，提供正确的答案也会有所帮助可重复的内容

因为我无法评估问题中难以理解的表达式，我在下面提供了一个演示，看看这是否是被问到的

帮助编译和链接

structnest:\>type "c:\Program Files\Microsoft Visual Studio 10.0\VC\compile.bat"

@ECHO OFF
REM Compile and Link Helper Utility.
REM Add New Entry CompileMe in Visual_Studio_IDE->Tools->ExternalTools.
REM Provide path to this bat file in command
REM Provide $(ItemFileName)$(ItemExt) as Arguments
REM $(BinDir) as Initial Directory
REM Enjoy One Click Compile & link Simple Single File Demo Sources
@call "C:\Program Files\Microsoft Visual Studio 10.0\VC\vcvarsall.bat" x86
cl /Zi /nologo /W4 /analyze %1% /link /RELEASE
pause

源文件详情

structnest:\>dir /b
structnest.cpp

structnest:\>type structnest.cpp
#include <windows.h>
#include <winternl.h>
#include <stdio.h>
#define SOMESIZE 20

typedef VOID (NTAPI *g_RtlInitUnicodeString) (PUNICODE_STRING DestinationStri
ng, PCWSTR SourceString );

#pragma pack (1)
typedef struct _OUTNEST
{
    int a;
    int b;
    short c;
    UNICODE_STRING Nestin;
}OutNest,*POutNest;
#pragma pack()

int main (void)
{
    POutNest MyNest = ( POutNest  ) calloc ( 0x01  , sizeof(OutNest)   );
    PWSTR    buff   = ( PWSTR     ) calloc ( 0x30 ,  sizeof(wchar_t)   );
    HMODULE hMod = LoadLibrary("ntdll.dll");
    if ( (hMod != NULL) && (MyNest != NULL)  && (buff != NULL))
    {
        g_RtlInitUnicodeString RtlInitUnicodeString = ( g_RtlInitUnicodeString )
 GetProcAddress ( hMod , "RtlInitUnicodeString");
        if (RtlInitUnicodeString != NULL )
        {
            for (int i = 0; i< SOMESIZE; i++)
            {
                swprintf_s(buff, 0x29 , L"this is string number %.2d",i);

                RtlInitUnicodeString(&MyNest->Nestin,buff);
                printf("%S\n",MyNest->Nestin.Buffer);
            }
            printf("done\n");
            goto getout;
        }
        printf("GetprocAddress failed\n");
        goto getout;
    }
    printf("calloc() %p %p LoadLib %p failed\n" , MyNest,buff,hMod);
getout:
    if (MyNest)
        free(MyNest);
    if(buff)
        free(buff);
    if(hMod)
        FreeLibrary(hMod);
    return 0;
}
structnest:\>"c:\Program Files\Microsoft Visual Studio 10.0\VC\compile.bat" stru
ctnest.cpp
Setting environment for using Microsoft Visual Studio 2010 x86 tools.
structnest.cpp
Press any key to continue . . .

structnest:\>dir /b *.exe
structnest.exe

structnest:\>structnest.exe
this is string number 00
this is string number 01
this is string number 02
this is string number 03
this is string number 04
this is string number 05
this is string number 06
this is string number 07
this is string number 08
this is string number 09
this is string number 10
this is string number 11
this is string number 12
this is string number 13
this is string number 14
this is string number 15
this is string number 16
this is string number 17
this is string number 18
this is string number 19
done

脚本文件详细信息

structnest:\>type c:\nestedbreak.txt
as /mu ${/v:mystr} @@( MyNest->Nestin.Buffer );
.block { r $t0 = $spat( "${mystr}", "*11" ); }
.if( @$t0 != 1 ) { gc } ;

explanation of script file

as /mu ${/v:mystr}
Sets the alias equivalent equal to the null-terminated Unicode string 
that begins at Address @@( MyNest->Nestin.Buffer ). 
.block {} to force alias evaluation.
a Pseudo register $t0 is set to the result of $spat() can be 0 or 1

"${mystr}" on alias evaluation will become "this is string number 00" 
a Double Quoted string not address or some other expression 

"*11" is again a Double Quoted wild card pattern string it will match "11"
 at any position in the Input String .

.if is a conditinal that will break only when @$t0 == 1

现在，我们有一个稍微更加理解的情况，其中每一个表达式是独立可验证的，我们在断点处使用它来进行程序化

执行详情

structnest:\>cdb -c ".lines;g main;r;.echo SET A CONDITINAL BREAK POINT AND RUN
THE EXE;bp `:32` \" $$^>a^< c:\\nestedbreak.txt \";g ;.lastevent;.echo why did w
e break here ? now that we broke lets go again;g;q " structnest.exe

explanation as follows

cdb.exe      console mode windbg;
.lines;     load line information (lineinfo default off in cdb.exe needed to set bp on src lines)
g main;     ( we are interested in our code for which we have src not some random system module)
r;      print the registers to confirm we reached main properly
.echo       just a signal to show that we are alive and kicking
`:32` "$$>a< c:\\nestedbreak.txt"   conditional break point on src line 32 ( inner double quotes/ unaccpetable > < chars escaped )
g;      run the exe
.lastevent;     shows the reason why we broke;
.echo       a signal to indicate that we broke
g;q;        finish running the exe and quit debugger

执行输出详细信息

structnest:\>cdb -c ".lines;g main;r;.echo SET A CONDITINAL BREAK POINT AND RUN
THE EXE;bp `:32` \" $$^>a^< c:\\nestedbreak.txt \";g ;.lastevent;.echo why did w
e break here ? now that we broke lets go again;g;q " structnest.exe

Microsoft (R) Windows Debugger Version 6.12.0002.633 X86

0:000> cdb: Reading initial command '.lines;g main;r;.echo SET A CONDITINAL BREA
K POINT AND RUN THE EXE;bp `:32` " $$>a< c:\\nestedbreak.txt ";g ;.lastevent;.ec
ho why did we break here ? now that we broke lets go again;g;q '

Line number information will be loaded

eax=00034180 ebx=7ffd6000 ecx=00000001 edx=0041a5f0 esi=00000000 edi=00000000
eip=00401000 esp=0013ff7c ebp=0013ffc0 iopl=0         nv up ei pl zr na pe nc
cs=001b  ss=0023  ds=0023  es=0023  fs=003b  gs=0000             efl=00000246
structnest!main:
00401000 55              push    ebp


SET A CONDITINAL BREAK POINT AND RUN THE EXE

this is string number 00
this is string number 01
this is string number 02
this is string number 03
this is string number 04
this is string number 05
this is string number 06
this is string number 07
this is string number 08
this is string number 09
this is string number 10
Last event: 16d0.2784: Hit breakpoint 0
  debugger time: Thu May 15 16:10:10.625 2014 (UTC + 5:30)
why did we break here ? now that we broke lets go again
this is string number 11
this is string number 12
this is string number 13
this is string number 14
this is string number 15
this is string number 16
this is string number 17
this is string number 18
this is string number 19
done
quit:

structnest:\>

Answer 2

您可以对windbg使用python扩展名。它允许使用python回调设置条件断点。

kd>!pycmd
>>>myApp = module("MyApp.exe")
>>>setBp( myApp.Func1, lambda : getParam("var2").filed3 > 10 )
>>>quit()
kd>g

你可以看到： 1）myApp.Func1 - pykd通过符号信息查找偏移量 2）getParam（“var2”） - pykd查找函数参数 3）getParam（“var2”）。filed3 - 它很容易使用结构

Windbg条件断点，在嵌套结构中使用字符串比较

2 个答案: