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Re: HTTPD bug
From: baba () beckman uiuc edu (Baba Z Buehler)
Date: Mon, 17 Apr 1995 08:25:34 -0500


Mr Martin J Hargreaves <ch11mh () surrey ac uk> writes:

On Sun, 16 Apr 1995, Mr Pink wrote:


Hello all,
i was browsing thru alt.2600, as you do, and spotted something of interest
it appears there is a problem with the CERN httpd.

It allows you to create a directory in a users home dir that can be 
accessed via mosaic/netscape.  well the bad bit of news is, if you sym link
this dir to root (/), file ownership becomes non existent.

i was easily able to read the shadow passwd file!


      This may also be possible with the NCSA daemon. You can set the 
FOLLOW_SYMLINKS variable in $SERVERROOT/conf/access.conf I believe to 
prevent the NCSA one from following any symlinks. However I think it 
defaults to following them. Haven't tested the file permissions under 
these conditions. I think there is a hole if he could read the shadow 
passwords, but that good server admin (not allowing symlinks from user 
directories, not running httpd as root, etc) may prevent the attack 
(possibly why it hasn't been found until now)...


the httpd process will read files with the permissions of the user it is
running as.  if you run your httpd as root, then you've got a problem.

run httpd as user 'nobody' or some such, and you won't have this problem.

--
# Baba Z Buehler - 'Hackito Ergo Sum'
# Beckman Institute Systems Services, Urbana Illinois
#
#   UNIX . . . best if used before: Tue Jan 19 03:14:08 2038 UTC
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# WWW: http://www.beckman.uiuc.edu/groups/biss/people/baba/
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