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CGIWrap - Comments from Administrators
It is inherently impossible to provide _total_ protection, but there is a nifty little utility called cgiwrap that can help. Check out
the URLs:
http://www.umr.edu/~cgiwrap/
ftp://ftp.cc.umr.edu/pub/cgi/cgiwrap/
This method has several advantages:
1. It runs the cgi script as your userid, not as some server-defined
userid. Assuming you are an ordinary user, this reduces the risk
of damaging the system, while increasing the risk of mucking-up
your own files. That tradeoff is precisely what many admins
on big sites want; it shifts the risk from a badly-written
script onto its author, rather than the sysadmin. Also, the
fact that it runs as you means that if you do something dumb
or nasty with it, the administrators have a better chance of
determining who is responsible.
Also, this means that if a cgi script hangs and fails to die, you
can kill it yourself; if it runs as some special userid then only
the system administrator can kill it should it run amuck.
2. It does some security checking for common holes. For instance,
it checks that the owner of the directory where the script is
found also owns the script.
3. If you call cgiwrap as cgiwrapd then you'll get special debugging
output; I've found this extremely helpful in testing.
Nothing is bulletproof. The simple act of letting users create static
html documents is itself something of a risk. For example, on many
UNIX-based WWW servers, any user can type the following:
cd ~/public_html
ln -s /etc/passwd Read_This_Folks
^^^^^^^^^^^^^^^or whatever ;-)
And you've just let the entire universe see your system's password
file! Of course, this is monumentally stupid, and of course many
newer systems use shadow passwords, but I'm sure more subtle holes
exist even with static html -- to say nothing of cgi scripts.
Also, take a look at the URL:
http://www-genome.wi.mit.edu/WWW/faqs/www-security-faq.html
for some _very_ useful information about cgi security issues.
--------
Matthew.Healy@yale.edu Postdoc (& now, WebMaster)
Center for Medical Informatics, Yale School of Medicine
He was covered with clanking chains of code. "I am the
Ghost of Hacks Past," he said to Scrooge.
http://paella.med.yale.edu/~healy/matt_healy.html
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