ARE YOU NUTS?
Since you have arrived at this page, I must conclude that one of
the following is true:
Assuming that it's one of the first two, let's have a discussion about
security (or the lack thereof) for the world wide web.
- you have a death wish
- you are a thrill seeker
- you have a criminal streak
The truth of the matter is that all of the attacks that were
described on the previous page are possible to carry out, and will
succeed with varying probabilities depending on the configuration of
the machine. In order to put your mind at ease, there are no viruses
or attacks carried out from web pages on this machine (that I know
of!). All of the links on the previous page lead here.
The world wide web carries quite a bit of risk with it for both servers and
clients. The reasons for this are too complex to discuss in detail here,
but can be summarized as follows:
It's a dangerous world that we live in, and you should be careful about
what you do. Practice safe computing and communicating.
- machines connected to networks have no mean of defense against denial of
- the programs that are running both as clients and as servers are far
too complicated to be trustworthy. Hackers are trying every day to find new
ways to cause failurs in programs, and they are succeeding.
- the base protocols used by the internet (e.g., DNS, SMTP, and TCP/IP)
were designed under the assumption that machines and users on the network
were cooperative rather than adversarial. The historical restrictions
on security technology have inhibited the improvement of the situation by
preventing deployment of more secure systems.
- if you think about it, web browsers are retrieving data from the
internet and then acting on it (i.e., they are using foreign data as program
input). This is an invitation to disaster from importing viruses.
- Companies are getting interested in the internet as a means of
telemarketing, but some web browsers are happily supplying more information
about you to the world that you realize. Your email may soon become
as irritating as the phone system.
Here are some guidelines about how to safely use a browser:
If you are configuring a server, there are some additional cautions:
This may serve to scare you into not using the internet at all. If it does,
then you can always go back to using paper (but check your mail to make sure
it is not ticking before you open it). I'll be out there using the Internet
because I think there are overwhelming benefits from widespread dissemination
of information. Remember the following quote:
- Pay attention to the
CERT and CIAC advisories on vulnerabilities or
- Keep your configuration as simple as possible so you can understand it.
- Don't put your server on a machine with mission-critical data or
functions. Also don't put your server machine on a common broadcast
network (e.g., ethernet) with machines having such data or functions.
- Watch the logs on your machine to detect unusual activity.
- If you are using the NCSA http daemon, make sure that you install
the most recent version. The early versions had a bug that allowed people
to overflow the stack and end up running programs on your server machine.
- If you are using the NCSA http daemon and you allow cgi scripts to be
run, then make sure that you check these scripts or apply the
patch to protect the log files.
- Don't get smug if you are running a server other than the NCSA server.
The reason that bugs are found in this one is that the code is available,
and many people work on it. The other servers are just waiting to be hit.
- If you choose to allow scripts to run from forms, make absolutely
sure you know what you are doing. Remember that he environment and arguments
for a script can be manipulated by their input.
- DON'T run anything as root that gets invoked by your server. This
applies particularly to running setuid programs on UNIX.
- Don't put much trust in the authentication and access control methods
used in http. Sending cleartext passwords across the internet is a
laughable practice. The *supposedly secure* alternatives that have been
suggested are only slightly better.
- Don't accept credit card numbers for services unless you clearly
understand your liability. Under the current environment where issues of
liability have not yet been tested, this probably means don't take them.
- This is only a list to get you started. See the
for further information.
Security is mostly a superstition. It does not exist in nature,
nor do the children of men as a whole experience it. Avoiding
danger is no safer in the long run than outright exposure. Life
is either a daring adventure, or nothing. -- Hellen Keller
It has been brought to my attention that there are many similarities between
this page and the one of Cheswick.
Return to the previous page.
Return to my home page.