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Re: Bug report on error channel endless loop with bad .forward



This problem is caused by permission on the root home dir, default to
(700).  We noticed that whenever the "o" permission our user's home
dir is set to "0", the users get error messages about .forward
expansion.

Instead of putting .forward for root, we use the alias file.

On Mon, Mar 19, 2001 at 02:02:39PM -0600, Crispin Bivans wrote:
> Situation: On a Unix with sendmail,  I always made it a practice to put a
> '.forward' in roots home directory that emailed my Outlook account with any
> root messages but *also* kept a backup copy of the message in roots mailbox
> using the syntax of '\root' in the .forward file. This is a well defined
> behavior in .forward files to prevent endless alias expansion. After
> upgrading the machine to zmailer, the first time an email went to root, it
> started a chain-reaction endless looping error message in roots mailbox
> about an invalid .forward file (it doesn't like the '\' character).
> 
> Either error channel needs to recognize these looping situations and stop
> itself after a few times or the code that handles .forward file should start
> recognizing the '\' syntax. Seems like normal users could use exploit this
> flaw to do a local Denial of Service attack on /var disk space.
> 
> -Crispin
> bivansc@rotaryintl.org <mailto:bivansc@rotaryintl.org> 
> 

-- 

Grace He			
Ryerson University - School of Computer Science	
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Fax   : (416) 979-5064