BugTraq
Microsoft Windows GRE WMF Format Multiple Memory Overrun Vulnerabilities Jan 07 2006 08:07AM
frankruder hotmail com
Microsoft Windows GRE WMF Format Multiple Memory Overrun Vulnerabilities

by cocoruder
page:http://ruder.cdut.net
email:frankruder_at_hotmail.com

Last Update:2006.01.07
class:design error
Remote:yes
local:yes

Product Affected:
Microsoft Windows XP SP2
Microsoft Windows XP SP1
Microsoft Windows Server 2003 SP1
Microsoft Windows Server 2003
Microsoft Windows ME
Microsoft Windows 98se
Microsoft Windows 98
Microsoft Windows 2000SP4

Vendor:
www.microsoft.com

Overview:
Microsoft Windows GRE(Graphics Rendering Engine) has been discovered multiple memory overrun vulnerabilities while rendering WMF format file.Users who view the malicious WMF format file will bring a denial of service attack(explorer.exe will be restart).

Details:
there is 2 memory overrun vulnerabilities at least.

1.ExtCreateRegion call result in memory overrun vulnerability
HRGN ExtCreateRegion(
CONST XFORM *lpXform, // transformation data
DWORD nCount, // size of region data
CONST RGNDATA *lpRgnData // region data buffer
);

WMFRECORD structure:
typedef struct _StandardMetaRecord
{
DWORD Size; /* Total size of the record in WORDs */
WORD Function; /* Function number (defined in WINDOWS.H) */
WORD Parameters[]; /* Parameter values passed to function */
} WMFRECORD;

the Parameters is likely about:
typedef struct _Parameters
{
char unknow1[0x0a];
WORD All_PointtStruct_Num; //the total following " PointtStruct" number
char unknow2[0x0a];
char PointtStruct[]; //first "PointtStruct"
}Parameters;

"PointtStruct" structure:
typedef struct _PointtStruct
{
WORD PointNum; //
WORD Point[PointNum]; //
char unkonow[6];
}PointtStruct;

if we set 0xff to WMFRECORD.Function,PlayMetaFileRecord will compute the memory which will be allocate later,as following:

.text:7F00FE07 loc_7F00FE07: ; CODE XREF: PlayMetaFileRecord+1256j
.text:7F00FE07 sub eax, 3
.text:7F00FE0A jnz loc_7F022B9A ; 0xff
.text:7F00FE10 movzx ecx, word ptr [ebx+10h] ;get total "PointtStruct" number
.text:7F00FE14 mov [ebp-88h], ecx ;save
.text:7F00FE1A test ecx, ecx
.text:7F00FE1C jnz short loc_7F00FE2E ;jmp
.text:7F00FE1E xor eax, eax
.text:7F00FE20 push eax ; int
.text:7F00FE21 push eax ; int
.text:7F00FE22 push eax ; int
.text:7F00FE23 push eax ; int
.text:7F00FE24 call CreateRectRgn
.text:7F00FE29 jmp loc_7F010494
.text:7F00FE2E ; 哪哪哪哪哪哪哪哪哪
哪哪哪哪哪哪哪哪哪
哪哪哪哪哪哪哪哪哪
哪哪哪哪哪哪哪哪哪
哪?
.text:7F00FE2E
.text:7F00FE2E loc_7F00FE2E: ; CODE XREF: PlayMetaFileRecord+C15j
.text:7F00FE2E xor edi, edi
.text:7F00FE30 mov [ebp-8Ch], edi
.text:7F00FE36 lea eax, [ebx+1Ch] ;get first "PointtStruct" address
.text:7F00FE39 mov [ebp-90h], eax ;save
.text:7F00FE3F and [ebp-94h], edi
.text:7F00FE45 and [ebp-98h], edi
.text:7F00FE4B test ecx, ecx
.text:7F00FE4D jbe short loc_7F00FE8C
.text:7F00FE4F
.text:7F00FE4F loc_7F00FE4F: ; CODE XREF: PlayMetaFileRecord+C83j
.text:7F00FE4F movzx ecx, word ptr [eax] ;get PointNum,here will trigger memory access error**
.text:7F00FE52 mov edx, ecx
.text:7F00FE54 shr edx, 1 ;PointNum/2
.text:7F00FE56 add edx, edi ;sum PointNum/2
.text:7F00FE58 cmp edx, edi
.text:7F00FE5A jb loc_7F0106D5
.text:7F00FE60 mov edi, edx
.text:7F00FE62 mov [ebp-8Ch], edi
.text:7F00FE68 cmp ecx, 7FFFFFFBh
.text:7F00FE6E jnb loc_7F0106D5
.text:7F00FE74 lea eax, [eax+ecx*2+8]
.text:7F00FE78 inc dword ptr [ebp-98h] ;counter+1
.text:7F00FE7E mov ecx, [ebp-98h]
.text:7F00FE84 cmp ecx, [ebp-88h] ;cmp total "PointtStruct" number
.text:7F00FE8A jb short loc_7F00FE4F ;traverse all "PointtStruct"
.text:7F00FE8C
.text:7F00FE8C loc_7F00FE8C: ; CODE XREF: PlayMetaFileRecord+C46j
.text:7F00FE8C ; PlayMetaFileRecord+14D8j
.text:7F00FE8C cmp dword ptr [ebp-94h], 0
.text:7F00FE93 jnz loc_7F022BA2
.text:7F00FE99 cmp edi, 0FFFFFFDh
.text:7F00FE9F jnb loc_7F022BA2
.text:7F00FEA5 mov eax, [ebp-8Ch]
.text:7F00FEAB add eax, 2
.text:7F00FEAE shl eax, 4
.text:7F00FEB1 mov [ebp-9Ch], eax
.text:7F00FEB7 push eax ; uBytes
.text:7F00FEB8 push 0 ; uFlags
.text:7F00FEBA call ds:LocalAlloc ;will allocate memory normally.
.text:7F00FEC0 mov edi, eax

so when we set "Parameters.All_PointtStruct_Num","PointtStruct.PointNum" big enough,but not many enough "PointtStruct" structure,will trigger a memory access error on 7F00FE4F.

2.ExtEscape POSTSCRIPT_INJECTION result in memory overrun vulnerability
int ExtEscape(
hdc, // handle to DC (HDC)
POSTSCRIPT_INJECTION, // nEscape param of ExtEscape
cbInput, // size of input buffer
lpszInData, // pointer to input (PSINJECTDATA *)
0, // cbOutput param of ExtEscape
NULL // lpszOutData param of ExtEscape
);

we can control cbInput and szInData,so when we set cbInput big enough(like 0xffff),but set szInData very small,will trigger a memory access error(7F027358) likely.

.text:7F027312 loc_7F027312: ; CODE XREF: ExtEscape+11Ej
.text:7F027312 ; ExtEscape+12Aj
.text:7F027312 test byte ptr [ecx+4], 40h
.text:7F027316 jnz loc_7F017CEC
.text:7F02731C mov ebx, [ebp+arg_8] ;we can cotrol this:cbSize
.text:7F02731F add ebx, 1Ah ;cbSize+0x1a
.text:7F027322 and ebx, 0FFFFFFFCh ;cbSize+0x1a-4
.text:7F027325 mov eax, large fs:18h
.text:7F02732B mov eax, [eax+30h]
.text:7F02732E push ebx
.text:7F02732F push 0
.text:7F027331 push dword ptr [eax+18h]
.text:7F027334 call ds:RtlAllocateHeap ;allocate memory size=cbSize+0x16
.text:7F02733A test eax, eax
.text:7F02733C jz short loc_7F027385
.text:7F02733E mov ecx, [ebp+arg_4]
.text:7F027341 mov [eax+0Ch], ecx
.text:7F027344 mov ecx, [ebp+arg_8]
.text:7F027347 mov [eax+10h], ecx
.text:7F02734A mov edx, ecx
.text:7F02734C shr ecx, 2
.text:7F02734F sub ebx, 8
.text:7F027352 mov [eax+8], ebx
.text:7F027355 lea edi, [eax+14h]
.text:7F027358 rep movsd ;copy,here will trigger a memory error likely**
.text:7F02735A mov ecx, edx
.text:7F02735C and ecx, 3
.text:7F02735F rep movsb
.text:7F027361 mov ecx, [ebp-4]
.text:7F027364 mov edi, [ebp+arg_14]
.text:7F027367 lea edx, [ecx+48h]
.text:7F02736A mov esi, [edx+4]
.text:7F02736D mov [eax+4], esi

Exploit:
first vul can test like this:
...05020000FF0044444444444444444444FFFF33333333333333333333FFFF41424344.
..
second vul can test like this:
...0502000026001610FFFF4444444444444444...
my blog can not be opened now:p,i will upload the exploit files to xfocus(www.xfocus.net) later,have fun:)

Solution:
Microsoft has not develop the patch,please unregister the Windows Picture and Fax Viewer (Shimgvw.dll)(see MS06-001).

Thanks:
thanks all my friends,Happy Weekday:)

-EOF-

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