smbmount problem?

From: Chris Evans (chrisat_private)
Date: Tue Apr 21 1998 - 04:05:43 PDT

  • Next message: David LeBlanc: "Re: NT configuration caution"

    Hi,
    
    smbmount is a linux program to mount NT filesystem shares.
    
    /usr/sbin/smbmount //a/b /
    /usr/sbin/smbmount must be installed suid root
    
    Ohhh, that's nice. On my system (RH) it doesn't seem to be, which is
    probably very lucky! I expect it might be suid on other distributions
    maybe?
    
    # export USER=`perl -e 'print "A" x 10000'`
    # /usr/sbin/smbmount //a/b /
    Segmentation fault
    
    The buffer overflowed is on the stack, however it's of the form
    
    struct a {
      .. blah ..
      char user[32];
      .. blah ..
    };
    
    int
    main()
    {
      struct a;
    
      strcpy (&a.user, getenv("USER"));
    }
    
    
    I am interested to know if we can do anything malicious with this, since
    obviously the function "main" doesn't return and hand control to our
    overwritten stack frame. The eventual segfault is from within libc.
    
    Can someone enlighten us as to what use an overflow on the stack in
    functiom main() is? Aleph? :-)
    
    Cheers
    Chris
    



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