Quick 'n Easy FTP Server pro/lite Logging unicode stack overflow

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IHS Iran Homeland Security Public advisory
by : c0d3r "Kaveh Razavi" [email protected]

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Title : Quick 'n Easy FTP Server pro/lite
Logging unicode stack overflow

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information :

Quick 'n Easy FTP Server is a simple and handy FTP server which is
developed by Pablo van der Meer . there is a unicode overflow in the
logging process ,after enough long string sent as an argument of a
command when you go to the logging section overflow happens and
SEH gets hit .

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simple exploitation :

it is a unicode overflow so any code execution wont be stable .
here is a sampe way to trigger the vulnerability :
login to the FTP Server then try :
command aaaaa < about 1100 a (0x61) here > aaaa
then in the ftp server main window go to Logging section .
the FTP Server will crash . and in the ftptrace.txt we have :
24/07/2006 20:41:53.500 Exception caught by MainExceptionHandler():
Exception : c0000005
Address : 00610061
Access Type : write
Access Address : 00000000
the amazing part is if your string was large enough the ftp server
detect overflow and prevents from any pointers overwrite .

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Risk Rate : Medium

1) it is a unicode overflow , and exploitation wont be stable because
of the vulnerability's nature .
2) successful exploitation needs the admin go to the logging section .
3) it needs authentication .

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workaround :

no patch , all targets are vulnerable.

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Disclosure timeline :

March 26 , 2006 : vender contacted
March 27 , 2006 : vender replyed *
March 27 , 2006 : vender contacted , example provided
March 28 , 2006 : vender replyed **
March 28 , 2006 : vender contacted , C code provided to test the vuln.
March 29 , 2006 : vender replyed ***
April 25 , 2006 : public release

• vender says I haven't applyed all the microsoft updates while I
  have and of course an overflow issue in a software is not related
  to microsoft libraries .
  ** vender is insisting that the problem is not the FTP problem and my
  box problem .
  *** I sent him a C code to check the vulnerability , he said he will
  contact me . well he didn't .

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Credit :

all go to IHS team
www.ihsteam.com
www.ihsteam.net
www.c0d3r.org

greeting :

LorD and NT of IHS , Jamie of exploitdev.org ,
other friends of mine in www.underground.ir