Windows Metafile Multiple Heap Overflows

Release Date:
November 8, 2005

Date Reported:
March 29, 2005

Severity:
High (Code Execution)

Vendor:
Microsoft

Systems Affected:
Windows 2000
Windows Server 2003

Overview:
eEye Digital Security has discovered a heap overflow vulnerability in
the way the Windows Graphical Device Interface (GDI) processes Windows
enhanced metafile images (file extensions EMF and WMF).  An attacker
could send a malicious metafile to a victim of his choice over any of a
variety of media -- such as HTML e-mail, a link to a web page, a
metafile-bearing Microsoft Office document, or a chat message -- in
order to execute code on that user's system at the user's privilege
level.

Technical Details:
The Windows metafile rendering code in GDI32.DLL contains a number of
integer overflow flaws in its processing of EMF/WMF file data that lead
to exploitable heap overflows through any number of specially crafted
metafile structures.  For example, the following disassembly from
MRBP16::bCheckRecord demonstrates a size calculation that is susceptible
to integer overflow and as a result may pass validation with a dangerous
value:

    77F6C759    mov     edx, [ecx+18h]    ; malicious count (e.g.,
8000000Dh)
    77F6C75C    mov     eax, [ecx+4]      ; heap allocation size
     ...
    77F6C764    lea     edx, [edx*4+1Ch]  ; EDX >= 3FFFFFF9h: integer
overflow
    77F6C76B    cmp     edx, eax          ; validation check
    77F6C76D    jnz     77F6C77F

Protection:
Retina Network Security Scanner has been updated to identify this
vulnerability.
Blink Endpoint Protection proactively protects users from this
vulnerability.

Vendor Status:
Microsoft has released a patch for this vulnerability. The patch is
available at:
http://www.microsoft.com/technet/security/bulletin/MS05-053.mspx 

Credit:
Fang Xing

Related Links:
This vulnerability has been assigned the following IDs;

EEYEB-20050329
OSVDB ID: 18820
CVE ID: CAN-2005-2124

Greetings:
Thanks Derek and and eEye guys help me wrote this advisory. Greeting
xfocus guys and venustech lab guys.


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