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

Last Update:2006.01.07
class:design error

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


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).

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 */

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"

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

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
.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 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 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

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

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

thanks all my friends,Happy Weekday:)


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