Re: CERT Advisory CA-99.13 - Multiple Vulnerabilities in WU-FTPD

From: Charles M. Richmond (cmrat_private)
Date: Tue Oct 26 1999 - 23:45:59 PDT

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    > On Thu, Oct 21, 1999 at 03:05:22PM -0500, Rami Dass wrote:
    >
    > > Also, I beleive that this problem occurs only in certain OS's vulnerable
    > > to the getcwd() exploit, the ERRATA file, in the 2.6.0 source tree, lists
    > > them:
    > >
    > > "Systems needing getcwd():
    ...
    > >   OSF/1         (osf)
    ...
    
    Gregory A Lundberg <lundbergat_private> states:
    
    > It's a well-known fact that getwd() is not a good choice; it overruns
    > buffers.  getcwd() allows bounds checking and should be used instead.
    >
    > The systems listed above have no getcwd() function, or at least nobody has
    > reported those systems now have one, so we're still assuming they do not
    > (notice we're fixing _that_ class of assumptions by switching to autoconf).
    
    > Sun operating systems, in particular SunOS, provide the getcwd() function.
    > Testing has shown the results from that function are not reliable.
    
    Digital UNIX from 4.0b (uname -rsv - OSF1 V4.0 564) does have getcwd() as
    does Solaris 7 (2.7). Furthermore even if one does use getwd(), it has
    the following feature in both Solaris and in OSF/1 (DUNIX 4.0b):
    
     OSF/1
      The maximum pathname length, in characters, is set by the PATH_MAX defini-
      tion, as specified in the limits.h file.  If the length of the pathname of
      the current directory is greater than (PATH_MAX + 1), including the null
      byte, getwd() fails and returns a null pointer.
    
     Solaris
         If the length of the pathname of the current working  direc-
         tory  is  greater  than  ({PATH_MAX} + 1) including the null
         byte, getwd() fails and returns a null pointer.
    



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