Microsoft GDIPlus.DLL JPEG Parsing Engine Buffer Overflow

["Nick D." <ndebaggis@xxxxxxxxxxx>]

Microsoft GDIPlus.DLL JPEG Parsing Engine Buffer Overflow
-----------------------------------------------------------------
Advisory: September 14, 2004
Reported: October 7, 2003

Systems affected based on testing:
Windows XP SP0,SP1,SP1a (Home & Pro)

Systems potentially affected based on Microsoft's DLL Help Database
(there may be others):

gdiplus.dll    5.2.3790.0
  Windows Server 2003 Data Center
  Windows Server 2003 Enterprise
  Windows Server 2003 Standard
  Windows Server 2003 Web Edition

gdiplus.dll    5.1.3100.0
  Microsoft Visual Studio .NET (2003) Enterprise Architect

gdiplus.dll    5.1.3097.0
  Microsoft Visual Studio .NET (2002) Enterprise Architect
  Microsoft Visual Studio .NET (2002) Enterprise Developer
  Microsoft Visual Studio .NET (2002) Professional
  Microsoft Visual Studio .NET (2003) Enterprise Architect
  Visual Basic .NET Standard 2002
  Visual C# .NET Standard 2002
  Visual C++ .NET Standard 2002
  Windows XP Home 2002
  Windows XP Professional 2002

gdiplus.dll    5.1.3079.3
  Microsoft Visual Studio .NET (2002) Enterprise Architect
  Visio 2002 Professional
  Visio 2002 Standard


Description
------------------------

The JPEG parsing engine included in GDIPlus.dll contains an
exploitable buffer overflow.  When a specially crafted JPEG image is
accessed through the Windows XP shell, a buffer overflow occurs
potentially allowing an attacker to run arbitrary code on the
affected system.  Due to the pervasiveness of the affected dll there
may be other vulnerable attack vectors.


Technical
------------------------

JPEG Comment sections (COM) allow for the embedding of comment data
into a JPEG image.  COM sections are marked beginning with 0xFFFE
followed by a 16 bit unsigned integer in network byte order giving
the total comment length + the 2 bytes for the length field; a
single JPEG COM section could therefore contain 65533 bytes of
invisible data (invisible in the sense that it's not rendered as
part of the image).  Because the JPEG COM field length variable is 2
bytes wide, and itself is included in the length value, the minimum
value for this field is 2, this implies an empty comment.  If the
comment length value is set to 1 or 0, a buffer overflow occurs
overwriting heap management structures.

The problem is GDIPlus normalizes the COM length prior to checking
it's value; a starting length of 0 becomes -2 after normalization
(0xFFFE unsigned), this value is converted to the 32 bit value
0xFFFFFFFE and is eventually passed on to memcpy which attempts to
copy ~4G bytes into heap memory.

eEye Digital Security analyzed the bug and found that heap
management structures are left in an inconsistent state with
execution eventually reaching heap unlink instructions within
RTLFreeHeap with EAX pointing to a pointer to data we control and we
have direct control of EDX.


Vendor Status
------------------------

Patch available MS04-028 (833987)
http://www.microsoft.com/technet/security/bulletin/ms04-028.mspx


Detection
------------------------

Detection could be accomplished by examining the JPEG image for the
following byte sequence:

0xFF 0xFE 0x00 0x00 or 0xFF 0xFE 0x00 0x01


Credits
------------------------
Nick DeBaggis - Discovery, analysis, and advisory.

Special thanks to eEye Digital Security www.eeye.com - Detailed
vulnerability analysis, initial and ongoing vendor contact.

Also thanks to Networks Unlimited - Early bug testing.


Related Links
------------------------
Solar Designer, Openwall Project
Netscape Browser JPEG Vulnerability July 2000
http://www.openwall.com/advisories/OW-002-netscape-jpeg.txt