EEYEB-20051017 Windows Media Player BMP Heap Overflow

Release Date:
February 14, 2006

Date Reported:
October 17, 2005

Patch Development Time (In Days):  
60   

Severity:
High (Remote Code Execution)

Vendor:
Microsoft

Systems Affected:
Microsoft Windows Media Player 7.1 through 10

Windows NT 4.0
Windows 98 / ME
Windows 2000 SP4
Windows XP SP1 / SP2
Windows 2003

eEye ID: EEYEB-20051017
CVE: CVE-2006-0006

Overview:
eEye Digital Security has discovered a critical vulnerability in Windows
Media Player. The vulnerability allows a remote attacker to reliably
overwrite heap memory with user-controlled data and execute arbitrary
code in the context of the user who executed the player.

Windows Media Player has a security issue within Media Player versions
7.1 through 10 on all Windows os's. This flaw is a heap overflow, and an
attacker can use multiple vectors to exploit it.  Attackers can create
.asx files and open them with a URL, use activex embeded in an HTML page
or create a Media Player skin file.


Technical Description:

Windows Media Player can play bit map format files, such as a .bmp file
and use Windows Media Player (WMP) to decode the .dll process bmp file.
But it can't correctly process a bmp file which declares it's size as 0.
In this case, WMP will allocate a heap size of 0 but in fact,  it will
copy to the heap with the real file length. So a special bmp file that
declares it's size as 0 will cause the overflow. When changing the size
to 0, WMP will allocate the heap of the new function, so actually it
will allocate 0x2*8(heap) sized heap.  When we copy the date is will
check two conditions:

1.  less than the size - the bmp head, this is 0-0xe(the bmp head
size) = 0xfffffff2
2.  less than 0x1000

So if the real file size is less than 0x1000, it will copy the real date
size to the 0x2*8 heap, if the real file size is larger than 0x1000, it
will copy the first 0x1000 to the 0x2*8 heap.

Protection:
Retina Network Security Scanner has been updated to identify this
vulnerability.
Blink - Endpoint Vulnerability Prevention - preemptively protects 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/ms06-005.mspx

Credit:
Fang Xing

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