RE: directory traversal

From: Levenglick, Jeff (jlevenglickat_private)
Date: Thu Feb 07 2002 - 12:25:43 PST

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    Interesting.. <<not sure why i'm spending time on this.. but>> :)
    
    I did a few tests and found, I think, why you are getting your results. It
    looks like it
    is some sort of overflow. I'm assuming that MS added code to stop a crash of
    cmd, but might
    of missing something. 
    
    From testing and debuging I have found that after putting an overflow, in
    this case ....'s the system
    'forgets' the drive. ie: It does not think it is on the C: drive any more.
    
    To prove this.. after your \............\'s do a cd winnt and it will fail.
    then do a cd c:\winnt\system32 
    and it will work. Do a cd \ and it will work. Do a cd \winnt\system32 again
    and it works. (until you do
    the ..'s again)
    
    
    Jeff
    
    
    -----Original Message-----
    From: Piyush Agarwal [mailto:pvagarwalat_private]
    Sent: Thursday, February 07, 2002 3:13 PM
    To: Levenglick, Jeff; Jim Nanney; Strumpf Noir Society
    Cc: vuln-devat_private
    Subject: RE: directory traversal
    
    
    hi,
    It seems you are right...
    But here is something more that I found:
    
    (Running cmd.exe on Win2k)
    Microsoft Windows 2000 [Version 5.00.2195]
    (C) Copyright 1985-2000 Microsoft Corp.
    
    C:\>cd winnt\system32
    
    C:\WINNT\system32>cd \.\
    
    C:\>cd winnt\system32
    
    C:\WINNT\system32>cd \..\
    
    C:\>cd winnt\system32
    
    C:\WINNT\system32>cd \...\
    
    C:\>cd winnt\system32
    
    C:\WINNT\system32>cd \....\
    
    C:\>cd winnt\system32
    
    C:\WINNT\system32>cd \.........\
    
    C:\>cd winnt\system32
    The system cannot find the path specified.
    
    C:\>cd winnt\system32
    The system cannot find the path specified.
    
    C:\>cd winnt
    The system cannot find the path specified.
    
    C:\>
    
    It seems that the cd command just stops working when I
    carried out the above steps......weird!! Anybody care
    to explain ?
    
    Regards,
    Piyush Agarwal
    
    
    --- "Levenglick, Jeff" <jlevenglickat_private>
    wrote:
    > I also tried it, but I think you might be missing
    > what it is doing.
    > 
    > It looks like it takes the cd \  and ignores
    > everything after it.
    > 
    > I tried  cd \.\ and cd \..\ and got the same results
    > 
    > -----Original Message-----
    > From: Piyush Agarwal [mailto:pvagarwalat_private]
    > Sent: Wednesday, February 06, 2002 1:31 PM
    > To: Jim Nanney; Strumpf Noir Society
    > Cc: vuln-devat_private
    > Subject: Re: directory traversal
    > 
    > 
    > On Win 2k (running cmd.exe)
    > 
    > C:\>cd winnt
    > 
    > C:\WINNT>cd system32
    > 
    > C:\WINNT\system32>cd \...\
    > 
    > C:\>
    > 
    > On same machine (now running Command.com)
    > 
    > C:\>cd winnt
    > 
    > C:\WINNT>cd system32
    > 
    > C:\WINNT\SYSTEM32>cd \...\
    > Invalid directory
    > 
    > C:\WINNT\SYSTEM32>
    > 
    > So u can see that on Win2K the triple dot traversal
    > works in cmd.exe but not in command.com......anyone
    > wanting to dig deeper in this ?? :-)
    > 
    > - Piyush Agarwal
    > 
    > 
    > --- Jim Nanney <jnanneyat_private> wrote:
    > > I'm just a lurker here, but a simple thought...
    > > 
    > > I saw this and thought well it probably has to do
    > > with cmd.exe of win2k
    > > 
    > > On my win2k machine using cmd.exe:
    > > ************************************
    > > 
    > > C:\>cd winnt\system32\drivers
    > > 
    > > C:\WINNT\system32\drivers>cd \...\
    > > 
    > > C:\>
    > > 
    > > on my win98 machine using command.com
    > > *************************************
    > > 
    > > C:\>cd windows\system32\drivers
    > > 
    > > C:\WINDOWS\SYSTEM32\DRIVERS>cd \...\
    > > Bad command or file name
    > > 
    > > C:\WINDOWS\SYSTEM32\DRIVERS>
    > > 
    > > Can't give you reasons why, but given the little
    > > information supplied I
    > > would bet it would be system calls opening a shell
    > > and thus the reason for
    > > the /.../ working on win2k and not 98.
    > > 
    > > --Jim Nanney
    > > 
    > 
    > 
    > 
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