ArticlesReader.com Menu

Newest Articles
Most Viewed Articles
ArticlesReader.com RSS
Submit Article
Login
Signup

Search the articles

Articles Main Categories

Advice
Animals
Automobiles
Business
Career
Communications
Computer Programming
Computers
Entertainment
Environment
Family
Fashion
Finance
Food
Health & Medical
Home & Garden
Humor
Internet Business
Internet Marketing
Legal
Leisure & Recreation
Marketing
Other
Politics
Reference & Education
Religion
Self Improvement
Sports
Technology & Science
Travel
Writing

Subscribe

Receive alert message from us when new articles submitted to our site for free.

Syndicate

Related Products

Home::Robert Plank

CGI Security Issues

Author : Richard Lowe

When you are creating or using CGI routines, you must be careful
to keep good coding techniques, security and just plain common
sense in mind. Sometimes you can do things that cause serious
unexpected site effects. In fact, sometimes you may think you
are making your CGI routine secure only to find out it just
doesn't work like you expected.

A good example of a this phenomenon is a simple CGI routine
called FormMail. This was written a number of years ago by a
fellow named Matt Wright to allow data to be entered in a form,
then emailed to a recipient.

I first looked at FormMail because I wanted to cut down on spam.
You see, my web site had my email address embedded on every
single page. I thought this was a good idea to allow people to
send me an email message when they wanted to contact me. In
fact, all of the web design books indicate that all good web
sites include an email link of this kind.

I soon discovered, much to my horror, that spammers use special
programs called Spam Harvesters to scan websites for email
addresses. They add these addresses to their mailing lists and
resell them over and over. The result is a large increase in the
amount of spam that I received.

After much research, I came to the conclusion that the best
defense against spam robots was to simply stop including my
email address on my web sites. This left the question of how to
allow users to contact me when they had questions or comments.

The answer is simple - use a form. The advantage is that the
email address is hidden within the CGI routine or a text file
and it is simply not possible for a spam harvester to pick it
up. As long as the email address is coded into the CGI routine
or in a database you are relatively secure.

However, many people use FormMail in a different way. Let's say
you want to allow your visitors to "tell a friend" about your
site. So you include a form which allows visitors to enter their
message and a target email address. If you are not very careful
you could find that you have set yourself up as a spam relay.

You see, spammers are always looking for ways to hide their
identity. One common method is to search the internet for
occurrences of FormMail. Sometimes I wonder if spammers rub
their hands together in glee when they find sites which use
FormMail with user-entered email addresses.

The spammer essentially "hijacks" the FormMail CGI routine and
causes it to send out emails as fast and furiously as they can.
I know of one instance where a spammer sent over one million
emails in a single day before someone noticed that their web
server was going very slowly (I wonder how long it would have
taken had the spammer tried limiting the load on the server so
it didn't show up as much). What happens here is very simple.
The FormMail CGI routine is simply called remotely by the
spammer, once for each spam email that he wants to send.

Ah, you say, but you could code the FormMail routine to check
the referrer field. This would surely prevent a spammer from
using it remotely, as his referrer would not be the website URL.

Sorry, no. The referrer field is actually a text string passed
to the CGI routine by the browser. The spammer is most likely
using a program which appears, to your web site, to be just
another browser. Since the spammer controls the program he can
code it to send the CGI routine whatever value he wants for the
referrer field.

As it turns out, it is very difficult to make a CGI routine such
as FormMail even relatively secure, and it may be impossible to
make it bullet-proof. All you can do is check enough things and
put in delays here and there to slow down and discourage
spammers.

You could, for example, only allow one posting per IP address
per hour. You could also check referrer just to block out the
more ignorant spammers. I suppose you could count the number of
times the routine is called, and have it just stop working after
a certain amount. For example, only allow one hundred calls per
day from anywhere.

The point here is not to tear apart the FormMail routine. The
goal is to show how difficult it can be to make anything secure
on the internet, and demonstrate that some assumptions (that the
referrer field is a valid check) may not be true in all cases.

What do you do? Before you implement any CGI or similar
interface, be sure and do a little research to be sure you
completely understand and handle the ramifications. If you don't
do this, you may find yourself the victim of a hacker or spammer.

Spam emails More free articles

More related feeds

Elliquiy Security, part I | Elliquiy Role Playing - RP, Stories ...
The following discusses a 'proactive' security issue - choice of software, specifically, mod_php versus cgi and fcgi. I will make an attempt at explaining these below. Elliquiy as you see it largely runs on a set of what are called ...

Freelance Project | fast SMTP needed for my VPS by paddumi
Spam and Email Security Issues on Plesk 8.2 VPS by maxon. We have over 50 domains on a Plesk 8.2 VPS server that all experience severe spam issues. We would like Qmail secured down as much as possible. Users are receiving mass amounts ...

Recordpub.com - Obama names security chiefs; Clinton, Gates among ...
The announcements rounded out the top tier of the team that will advise the incoming chief executive on foreign and national security issues in an era marked by wars in Iraq and Afghanistan and terrorism around the globe. ...

RedHat: Moderate: vim security update - The Community's Center for ...
Summary: Updated vim packages that fix security issues are now available for Red Hat Enterprise Linux 5. This update has been rated as having moderate security impact by the Red Hat Security Response Team. 2. ...

Recount - Rebuild error
if you are running php as a CGI under any web server (other than IIS) ; see documentation for security issues. The alternate is to use the ; cgi.force_redirect configuration below doc_root = ; The directory under which PHP ...

Straightfromthedoc: Insomnia Drug Can Help Jet-Lag and Shift-Work ...
(* Both email addresses are required for sending this article. They will never be shown or used for any marketing purposes). Please enter a message which will be shown together with the article:. Security Code: (Please help us to sort ...

AIRLINE BIZ Blog | The Dallas Morning News
Today, customers heading through Dallas Love Field will receive complimentary holiday socks as they head through security to keep their feet warm and toasty. Additionally, as customers board their flights, they will receive Old Navy ...

Re: Porblem with cgi pages - Technology Questions
incompatibility issues. They are addressing some of these in the next > version release IE8, but yes, some issues will remain unresolved, not > because of arrogance, but rather because of a strong customer and security > focus by MS. ...

Hacking Your SOX Off: Sarbanes Oxley, Fraud, and Fraudulent ...
Liability for investor losses in stock price based on: Disclosures that lessen consumer confidence Security issues that effect reliability and safety COBIT Control Objectives for Information and related Technology Security Policy ...

AIRLINE BIZ Blog | The Dallas Morning News
Security issues · Southwest Airlines · Southwest Airlines Pilots Association · Space · Transport Workers Union · Transport Workers Union of America · Transportation Security Administration ...

CGI Security Issues

Related articles