网上的文章都知道在HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Policies\Explorer 目录下有控制隐藏驱动器隐藏控制面板的键值,通过修改这些键值来控制是否可以改变windows的配置或者权限，或者掩藏或者显示什么。（必须要重新启动）那么谁来控制这个开关呢？
通过自己的调试追踪到如下的栈
# ChildEBP RetAddr Args to Child
00 0235f134 7602ed30 00000528 765aebe0 00000000 Sandboxdll!Mine_RegQueryValueExW+0xca [e:\ronggf\work\branches\minsheng\client_windows\src\hooklib\hook_advapi32.cpp @ 365]
WARNING: Stack unwind information not available. Following frames may be wrong.
01 0235f178 7602e977 00000528 765aebe0 0000ffff SHLWAPI!PathIsRelativeW+0xdf
02 0235f1bc 7602aed2 80000002 0235f210 765aebe0 SHLWAPI!SHRegGetValueW+0xe3
03 0235f1e0 7602b97e 80000002 0235f210 765aebe0 SHLWAPI!SHGetValueW+0x21
04 0235f41c 76024a79 00000000 765af510 765aebe0 SHLWAPI!Ordinal271+0x69
*** ERROR: Symbol file could not be found. Defaulted to export symbols for C:\Windows\system32\SHELL32.dll -
05 0235f43c 765aedb7 00000100 00000000 765aedc0 SHLWAPI!StrCmpNIW+0x40
06 0235f45c 766b1026 00000100 0235f4b8 00000004 SHELL32!SHRestricted+0x24
07 0235f474 766b07b3 00000000 02d80e68 00000000 SHELL32!Ordinal744+0x32a1
08 0235f494 766b0476 0235f4b8 02d36040 02d36010 SHELL32!Ordinal744+0x2a2e
09 0235f4e8 765685e5 02d80e68 00000001 0235f574 SHELL32!Ordinal744+0x26f1
*** ERROR: Symbol file could not be found. Defaulted to export symbols for C:\Windows\system32\explorerframe.dll -
0a 0235f538 7198d77d 02d36010 00000001 0235f574 SHELL32!OpenRegStream+0x1652
0b 0235f5b0 7198041e 02a5c2e0 01000000 80000000 explorerframe!Ordinal110+0xe380
0c 0235f5d0 765d619e 02a5c2f4 7fffffff 02a63668 explorerframe!Ordinal110+0x1021
0d 0235f5ec 765d6109 0235f628 00000000 02ac0fb8 SHELL32!SHCreateItemFromIDList+0x166
0e 0235f634 765caaa8 0235f64c 7602b6cf 02a63668 SHELL32!SHCreateItemFromIDList+0xd1
0f 0235f63c 7602b6cf 02a63668 0030e150 0235f6c0 SHELL32!Ordinal95+0x2274
10 0235f64c 771ab5e9 02ac0fb8 752c3f68 00294448 SHLWAPI!PathBuildRootW+0x4c
11 0235f6c0 771ae8d1 02ac0fb8 0030e150 752c3188 ntdll!RtlTestBit+0x21c
12 0235f820 75f81194 00294440 0235f86c 771db3f5 ntdll!RtlIsCriticalSectionLockedByThread+0x474
13 0235f82c 771db3f5 00294440 752c31c4 00000000 kernel32!BaseThreadInitThunk+0x12
14 0235f86c 771db3c8 771ad63e 00294440 00000000 ntdll!RtlInitializeExceptionChain+0x63
15 0235f884 00000000 771ad63e 00294440 00000000 ntdll!RtlInitializeExceptionChain+0x36
从 SHELL32.dll 的 函数 SHRestricted开始，转到读取策略注册表键值上去的，我们来看看 SHRestricted 的逆向
.text:7387F02B _SHRestricted@4 proc near ; CODE XREF: CMenuItemsCache::RefreshCachedDarwinShortcuts(int)+Dp
.text:7387F02B ; CDesktopBrowser::_ActivateView(void)+3Dp ...
.text:7387F02B
.text:7387F02B rest = dword ptr 8
.text:7387F02B
.text:7387F02B mov edi, edi
.text:7387F02D push ebp
.text:7387F02E mov ebp, esp
.text:7387F030 push offset ?g_lRestrictionsVersionNumber@@3JA ; long g_lRestrictionsVersionNumber
.text:7387F035 push 9Ch
.text:7387F03A push offset ?g_rgRestrictionItemValues@@3PAKA ; ulong * g_rgRestrictionItemValues
.text:7387F03F push offset unk_7387F058
.text:7387F044 push 0
.text:7387F046 push [ebp+rest]
.text:7387F049 call ds:__imp__SHRestrictionLookup@24 ; SHRestrictionLookup(x,x,x,x,x,x)
.text:7387F04F pop ebp
.text:7387F050 retn 4
.text:7387F050 _SHRestricted@4 endp
在其中调用了 SHLAPI.DLL 中的 SHRestrictionLookup
SHRestrictionLookup
函数如下：
int __stdcall SHRestrictionLookup(int a1, LPCWSTR pszDir, int a3, void *Dst, int a5, int a6)
{
char *v6; // edi@7
int v7; // ebx@1
unsigned int v8; // eax@2
int v9; // edx@3
v7 = 0;
if ( !g_bDllTerminating )
{
_ValidateRestrictionTable(Dst, a5, a6);
v8 = 0;
if ( (unsigned int)a5 > 0 )
{
v9 = a3;
while ( a1 != *(_DWORD *)v9 )
{
++v8;
v9 += 12;
if ( v8 >= a5 )
return v7;
}
v6 = (char *)Dst + 4 * v8;
v7 = *(_DWORD *)v6;
if ( *(_DWORD *)v6 == -1 )
{
v7 = SHGetRestriction(pszDir, *(LPCWSTR *)(a3 + 12 * v8 + 4), *(LPCWSTR *)(a3 + 12 * v8 + 8));
AcquireSRWLockExclusive(&g_csrwlockRestrictions);
if ( *(_DWORD *)a6 == SHGlobalCounterGetValue(GLOBALCOUNTER_RESTRICTIONS) )
*(_DWORD *)v6 = v7;
ReleaseSRWLockExclusive(&g_csrwlockRestrictions);
}
}
}
return v7;
}
会从注册表中获取值然后返回（如果没有获取 -1 没有获取），否则直接读取出来
在MSDN 中：
Determines whether a specified administrator policy is in effect. In many cases, applications need to modify certain behaviors in order to comply with the policies enacted by system administrators.
检测指定的管理员策略是否有效。在很多情况下，应用程序需要遵照系统管理员指定的策略依序修改某些行为。
系统行为是这个样子，如果我们的程序需要某些和系统行为不同，那么hook这个函数，并且返回和系统不同的值就能起到效果。
