Re: in.fingerd follows sym-links on Solaris 8

From: J. Bol (j.bolat_private)
Date: Mon May 28 2001 - 05:57:40 PDT

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    On a Solaris 8, i386 machine, I did the following:
    
    $ ls -al
    drwxr-xr-x  4  j      other   512 May 28, 14:12 .
    drwxr-xr-x  5  root   root    512 May 28, 14:10 ..
    lrwxrwxrwx  1  j      other     6 May 28, 14:12 .plan -> myplan
    -rw-------  1  nobody nobody   17 May 28, 14:12 myplan
    $ finger -l j@localhost
    [localhost]
    Login name: j
    Directory name: /export/home/j           Shell: /bin/sh
    Last login Mon May 28, 14:12 on console from :0
    No unread mail.
    No plan.
    
    After I changed the mod of myplan to world-readable, finger gave me
    
    $ finger -l j@localhost
    [localhost]
    Login name: j
    Directory name: /export/home/j           Shell: /bin/sh
    Last login Mon May 28, 14:12 on console from :0
    No unread mail.
    Plan:
    This is my plan.
    
    So I'd say in.fingerd is not vulnerable for the symlink attack you
    describe.
    
    J. Bol
    
    Lukasz Luzar wrote:
    
    > Hello,
    >
    >  Ok, the example wasn't good.
    >  It was a long day for me, thus, please forgive me that slip-up.
    >
    >  The sym-links attack is very useful when you want to read
    >  files that are readable only by unprivileged user.
    >
    >  On example, many httpd servers works with the same privilages,
    >  it means that you can read any CGI temporary file, and other
    >  files readable only by CGI scripts.
    >
    >  I think about a case where a CGI script saves some important
    >  information in a temporary file, like PHP do with the sessions:
    >
    >   -rw------- 1 nobody nobody    329 May 14 12:16  /tmp/sess_0cd156a633
    >
    >  When you have installed in.fingerd, and the in.fingerd is vulnerable,
    >  all local users are able to read the information from the files.
    >
    >  There are few other examples.
    >
    > --
    > Lukasz Luzar
    > http://Developers.of.PL/
    > Crede quod habes, et habes
    



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