IT Security in Libraries

Staying Safe Online

This is part four in my many part series on IT Security In Libraries. In Part Three I covered passwords. In part 2 we talked privacy. In Part One I tried to lay the foundation for security.

Today’s post is a big bunch of tips (in convenient list form) on how to keep yourself safe while surfing the web. A bundle of easy practical tips you can take anywhere to make your computers safer. This is a pretty long list that can be boiled down to three important bullet points:

  • Keep everything patched and updated
  • Never trust anything
  • Use good passwords


On your computer:

Keep that OS patched and updated. Related: Don’t use Windows XP
Disable hidden filename extensions
Make sure ALL those programs are updated. Especially don’t miss anything made by Adobe (e.g. Flash & Acrobat)
Never install things you’re not sure are safe. Especially don’t trust anything from Torrents or P2P sites. Avoid downloading programs from unknown sources
If you’re not using something, just remove it. Every program installed on your computer opens a potential new hole.
Make sure your firewall is turned on
Make sure file sharing is turned off
Use a reputable virus & malware protection software program, keep it up to date and run it often
Make sure that the Macro Virus Protection feature is enabled in all Microsoft applications
Never trust any links, attachments, short links, or anything else from anywhere or anyone unless you are SURE what’s inside
Have a recovery plan – Is your stuff backed up?
If it’s a laptop, use something like Prey Project
Advanced: Consider changing up your hosts file and/or using something like OPEN DNS.

Your Wi-Fi At Home:

Make sure you set a good password and use WPA or WPA2
Be sure to change the default Administrator Passwords (and Usernames)
Change the Default SSID and also disable SSID Broadcast
Turn off DHCP and set a fixed IP address range instead
Use MAC Address Filtering
When you’re not using it, just turn it off
Be sure to keep the firmware upgraded
Change your passwords every so often

Your Email:

Never open email attachments unless you know for sure what that file contains
Never click a link unless you know for sure where it leads is safe
Check your mail filters and forwards for things you didn’t add
Use good passwords
Sign out when you’re done
Use two factor authentication when possible (e.g. Google Authenticator for Gmail)
Be sure to use https when on public Wi-Fi
Consider using 2 separate email accounts to keep important things separate from everyday stuff
Watch out for short links, it’s hard to know where they’ll lead you

Your Browser:

Keep your browsers updated to the latest secure releases
Keep ALL Plugins updated to the latest secure releases, especially anything from Adobe
Don’t install things from sources you don’t trust
Block cookies, flash, and JavaScript (use with caution, will cause you trouble)
Use a password manager to store all your many passwords
Watch out for short links
A Few Recommended Plugins:

Your Social Media Stuff

Double check your apps. Make sure you know which applications have access to your profiles
Use two factor authentication when possible
Read the Facebook’s Guides in the Safety Center
Monitor and adjust your privacy & security settings
Use good passwords
Get more selective about sending and accepting friend requests. Don’t friend everyone.
Show “limited friends” a cut-down version of your profile
Facebook, Twitter and Gmail all offer help if you do in fact lose your accounts.

What about if you’re traveling?

Don’t do online banking or other financial transactions while away from home
Do not set your phone to automatically join any unlocked hotspot
Consider public computers in hotels and elsewhere dangerous
If you leave a laptop or other device in your hotel room, lock them up
Don’t post travel photos and writings on social network sites until you get home

What do you do AFTER you learned you’ve been hacked?

Change Your Passwords
Take that computer/server offline
Take as much time as you can to figure out what happened
Was it a password? Old program that had a hole in it?
If you can’t figure it out, you should probably format everything. Chances are good you can’t just patch things and keep on going. You may miss a backdoor or another open door, and the bad guys will still be around. Hopefully you had all the important stuff backed up and can start over from scratch.

Firesheep

Last but not least… make sure you’re familiar with something called Firesheep. I touched on this already in my post on privacy. It’s important for you to know just how easy it is for anyone to login as you on common sites you might be using every day. This is the number one reason you should never use an unsecured Wi-Fi connection when you’re out at someplace like Starbucks or Panera Bread, or anywhere else someone might be listening in. Firesheep makes it trivial for anyone to take over your online social life. It’s a simple little extension for Firefox that allows someone to grab your login to just about any website you’re using on your computer. See Also: Faceniff for Android mobile phones

Practical Advice On Choosing Good Passwords

This is Part Three in my many part series on IT Security In Libraries. In Part One I tried to lay the foundation for security. Last time we talked privacy, and today it’s passwords.

A comment on an LISNews post from last week asked me about passwords. It seems like such simple, obvious topic, but when you stop and think about it, passwords are difficult, and a good answer does indeed take 1,399 words.

Do you always use unique passwords? Are those passwords always “strong”? Does your library’s web presence require strong passwords for all users? Do you have password recommendation clearly posted on your web resources for your users? What makes a good password? Are complex passwords the most secure? Is it uniqueness? Is length the most important thing in a password? I’ll start by saying the single most important thing is uniqueness, never reuse a password on everything.

Password Reuse

Using the same password for everything is THE WORST thing you can do. If you learn just one thing from this post make sure it’s password reuse is dangerous. Doing this will allow anyone who gets your password from an insecure site (and the chances of this happening are probably higher than you’d think) to use it elsewhere. Your password could have been taken from any number of large data breaches and you’d never know it. When these big hacks happen the only thing saving you from becoming an easy target is having a unique password. It’s easy for a hacker to use your email address and password taken from a site like Gawker and use it as a starting point to cause some serious trouble.

How Did They Get Those Passwords?
So you probably wonder about how people are going to get your passwords. It’s rather easy for a talented hacker, and even easier to use automated tools to scan thousands of sites looking for vulnerabilities that would allow anyone with time to get your password from a site with a hole. Those usernames/passwords can then be sold to the highest bidder.
1. Ask: aka. Social engineering. They’ll just call the helpdesk and ask to have it reset.
2. Guess. Have your birthday on Facebook, your pet’s first name? That may just be enough.
3. Bruteforce. It’s trivial to have something that can guess millions of possible passwords in no time. (Your websites should never allow brute force attacks.)
4. Dictionary. Passwords follow predictable patterns and those are always tried first.
5. SQL Injections and other common vulnerabilities in websites.

What Makes A Good Password?
So what makes a good password? In short, length and complexity. If you think about it, a password is really weak security. If you’re in charge of setting the password policy for your library, you have decisions to make. Should you force people to use complex and unique passwords? Anytime you change up security policies people will look for ways around it. Enforcing strong passwords is no exception. Even when your users are forced to use “good” passwords, they’ll do something like choose all the characters on the left side of the keyboard. They will turn the seemingly secure restrictions into EASY passwords and make your network even LESS secure. Somehow your new security policy just made everyone’s password easier to guess. Those passwords are not strong and can be easily bruteforced/rainbowed/dictionaried because they are commonly used and will be guessed first in an automated attack. A truly strong password is darn hard to remember and that’s the problem for all of use with more than a few passwords.

What makes a bad password?
We have interesting stats on passwords thanks to some major hacks. In short, people choose bad passwords. They choose passwords that are short, all lower case, not random, they’re in the dictionary, they have no special characters, they’re found in password dictionaries, and worst of all, they’ll reuse the same password again and again across sites. That stats link has 3 interesting conculsions:
1. Passwords are inspired by words of personal significance or other memorable patterns.
2. Attempts to obfuscate or strengthen passwords usually follow predictable patterns.
3. Truly random passwords are all but non-existent – they’re less than 1% of the data set.
Don’t use any part of your username in your password. Don’t use any members of your family’s names. Avoid keyboard sequences, any real words, any real words with just a number tacked on either end, or any real word, just reversed.

Should You Change All Your Passwords Every 3 Months?
Before I cover some recommendations, I’ll ask, how often do you change your password? Is changing your passwords every 3 months a good idea? Is forcing your users to change their password every so often a good idea? I’ll stick my neck out and say, in general, no, changing your passwords every so often isn’t going to help things, with one exception: network or server logins. Network and server passwords should probably be changed every so often. I’ll explain why by first explaining why other things probably won’t matter. Say for example your bank… Your money is gone if anyone gets your password, you’ll notice that right away. You’ll only need to be change that one if it’s taken along w/ all your money. Your email? Chances are good if someone gets your email password they’ll start causing trouble right away. Hopefully you’ll be able to change it back and lock them out. In general: you don’t need to regularly change the passwords you use, UNLESS it’s to something like a network or a web server. The bad guys can just sit and wait once they’ve gotten into your network or your web server. They don’t need to do anything that will be instantly obvious like an empty back account. It may be good practice to change those types of passwords on a regular basis.

But I Can’t Remember All My Passwords!
If you’re like most people you probably have user accounts on what seems like an infinite number of sites. This makes using a unique password for each site next to impossible. PC Magazine recently did a nice round up of some of the many tools that can help you with this. If all that seems like too much, at the very least, have one easy to remember password for most common and unimportant websites. Then have a second password for things like facebook and twitter or other somewhat more important sites. Then have a third good solid password for banks & other super important things. If you have the same password for your network login at work and your account on LISNews, you’re doing it wrong. There are entire classes of websites for which you should simply pretend that your password is already public because you just shouldn’t trust them. You may also want to use a passwordcard, another simple idea to help you remember your passwords. Also, check out Diceware, Diceware™ is a method for picking passphrases that uses dice to select words at random from a special list called the Diceware Word List. Something similar, “Off The Grid” (grc.com).

Choosing A Good Password
Passwords don’t necessarily need to be hard. Pick a good memorization strategy, pick a good password, and you’ll be on your way to being more secure.
Choose NON obvious, NON dictionary passwords. If we assume someone has time to just sit and guess your password on a system, they will check common passwords first, then they check a dictionary. Since they don’t know your passwords, they look for the easiest guesses first. Given enough time, and if they are persistent enough, they will just start throwing every possible combination of letters, and then numbers, and then letters and numbers, and so on. So after using things that aren’t common, the most important thing is length. There’s no different between a simple long password as a complex long one as far as guessing goes. So start with an easy to remember password, then pad it with something else easy to remember. So get your own password and pad it. But don’t just use Password1 as this is easily guessed, and don’t pad by easily guessed numbers. The password plus padding shouldn’t be easily guessed or obvious. E.g. most common (therefore easily guessed) padding is done by adding a 1,2,3,4 at the end of some word. This increase in length and complexity defends against Brute Forcing. We get protection by adding more digits because they need to guess every possible combination of everything up to that length, each digit adds A LOT of time required. If you use special characters and upper/lower case you add even more time because they know most passwords are all lower case numbers. Some places will allow the use of spaces in your password, which gives you the opportunity to use a pass phrase e.g. Correct Horse Battery Staple.

Simple Things Make a Good Strong Password
At least 1 Uppercase
At least 1 Lowercase
At least 1 Number (And don’t put those numbers on the end)
At least 1 Something else (*%$@!-+=)
Make it as long as you can

Are complex passwords better? Well, maybe. Longer passwords are better, no doubt. If we knew exactly what each password was defending against, we would know what kind of password to choose. You have no idea how your passwords are stored or shared. Given enough time any captured password can be broken. Remember, we don’t know HOW people are going to get your password. Given enough time and resources any password can be guessed. BUT, that is no excuse to not use a good password, because chances are good no one will have the time and resources to crack a good password.

One more random piece of password changing advice, if you break up with someone who knew your passwords, change them all.

Practical Tips For Online Privacy

This is Part Two in my many part series on IT Security In Libraries. In Part One I tried to lay the foundation for security. This week we’ll talk privacy, and up next will be a general “Staying Safe Online” that will cover a million and one tips on how to keep you and your computer safe.

Privacy is a relative term. That is, the things that I consider important to my privacy, someone else might not care about. As librarians we usually key in on Confidentiality Threats. We want our patrons records safe. We also don’t share that information with ANYONE else. In general, we are fierce about protecting our patrons’ privacy. This is something that has always set us apart from everyone else. Amazon won’t do it. Google won’t do it. Do I even need to say Facebook won’t do it? People who come into the library or use our web sites don’t worry about what’s going to happen with their information (or at least they shouldn’t need worry about it). They should know we are doing our best to guard their privacy. Keeping all our IT resources secure should be a large part of guarding that privacy.

There are no big events, dead bodies or explosions in privacy violations. It’s something that is slowly eroding over time. The troubles are more subtle and are caused by errors, or intential misues and a shocking lack of transparency, accountability and security. We don’t think about privacy much, we only think about it when things are going wrong. Most people tend to think privacy isn’t very important, and don’t give it a second thought. Most companies make money by keeping our information as free as possible so it can be used, shared, and sold.

Let’s start this section with some general arguments FOR privacy, some reasons why privacy is so highly valued in our profession:

  • Invading a person’s privacy can give you access to information about them which you can then use against them, even if that information is not objectively illegal, immoral or unethical.
  • With privacy comes more freedom.
  • People invading your privacy are not infallible. They will overstep their bounds.
  • We don’t know how our information is used or stored.
  • We don’t know who has access to it.
  • We don’t know how or when we can fix mistakes.
  • We don’t know how long it’s stored
  • We don’t know what it’ll be used for in the future.
  • We don’t know how it may be distroted or manipulated
  • It can easily be misused on purpose or accidentally.
  • It can be stolen.
  • Privacy is not about hiding bad/illegal things.*

*This is the old “If you have nothing to hide then there is no reason for me to look” argument against privacy. The problem with the “nothing to hide” argument is the underlying assumption that privacy is about hiding bad things. Agreeing with this assumption concedes far too much ground and leads to an unproductive discussion of information people would likely want or not want to hide. It may indeed you have nothing to hide, but all the information that is being collected on all of us can certainly cause trouble.

I think that most librarians would agree with this statement from “The Eternal Value of Privacy”

“Privacy is an inherent human right, and a requirement for maintaining the human condition with dignity and respect. For if we are observed in all matters, we are constantly under threat of correction, judgment, criticism, even plagiarism of our own uniqueness”

So then what about when we are online?

More than ever we are being tracked & followed online, and what we do is used to build a database of personal information. So much of our communication is electronic, and so much of that leaves behind a trail, and that trail is recorded, and then bought and sold. We are volunteering an amazing amount of information online, through cookies and other tracking information, and we have no choice but to hope those databases are safe and secure. Your printer is spying on you, your passport Can Be Read from very long distances, your iPhone is recording where you go, Google is spying on you, Facebook is spying on you… it seems like it never ends.

Facebook is leading the way with its more permissive privacy settings. Mark Zuckerberg famously said, “There are new social norms now.” Facebook believes people are okay with reduced privacy, and that people don’t mind putting Facebook in control of their personal information. Facebook seems to think it gets to decide if you’re safe, secure and private. In general Facebook will default to openess and sharing of your information, because this is how they make money. Their “recommended settings” tend to share MORE rather than LESS. It recently became widly known Facebook is sharing cellphone numbers between Facebook friends, and one would be well advised to ask who else.

In a particularly egregious example of a total disregard for its users privacy, LinkedIn amended their 6000+ word “privacy” policy in a way that allows them to use your name and picture in social advertising. So LinkedIn will watch what you do, figure out what you might sell for them, and then use your name and picture in an endorsement they make for some crap they’ll stick on your friends pages. They also allowed your private information to be shared with unknown “third parties” for unknown purposes.

Other sites like Spokeo & Intelius can also take publicly available information about all of us and tie it together. The result is a frighteningly accurate picture of who we are, for sale to anyone.

There are ways to opt-out of most major tracking companies. However, a study by Stanford University Law School’s Center for Internet and Society has found that many online advertising networks are not adhering to their own privacy policies and continue to rely on and push out Web tracking cookies even after users have indicated that they do not wish to be tracked. Half of 64 online advertising firms did not remove their tracking cookies from the computers of consumers who had opted out of behavioral ad targeting. More recently, researchers at U.C. Berkeley have discovered that some of the net’s most popular sites were using a tracking service that can’t be evaded, even when users block cookies, turn off storage in Flash, or use browsers’ “incognito” functions.

And what about privacy on your cell phone? Do you know (or care) that your phone could be giving it away? Most applications get to decide what they have access to. We are given few choices and usually aren’t even aware of what the applications might be sharing. Fine grained control is lacking, and we are left with a take it or leave it situation when as app wants to have access to our phone. This can be used to access your phones location and identifiers to give advertisers and others insights into your habits.

We can begin to address issues of online tracking by considering some practical advice related to Facebook. Since it’s one of the more popular social sites that people use, it’s one of the more important sites to focus on. How can you make Facebook safer and more private?

  • Check your settings.
  • Be cautious of apps and links and anything shared by anyone.
  • Use https.
  • Never share anything that you don’t want read everywhere by everyone.
  • Know your friends. Do you really know who all your “friends” are?
  • Always watch for changes to your privacy settings by facebook.

Now in general, how can we all work to be more private online? Remember that YOU should decide what information about yourself to reveal, when, why, and to whom.

  • Turn on cookie notices in your Web browser, and/or use cookie management software.
  • All browsers have privacy settings: get to know them and change them to be more private.
  • Keep a “clean” e-mail address, one that is never given to anyone but trusted friends.
  • Don’t reveal personal details to strangers or just-met “friends”.
  • Check privacy (and https) settings on all social networks.
  • Realize you may be monitored at work: avoid sending personal e-mail to mailing lists, and keep sensitive files on your home computer.
  • Beware of sites that offer some sort of reward or prize in exchange for your contact information or other personal details.
  • Do not reply to spammers, for any reason.
  • Examine privacy policies and seals on sites you use.
  • Use BCC when forwarding emails.
  • Be careful with passwords (I’ll post an entire essay on passwords soon)
  • Check for unintentional content/metadata in photographs you post online (e.g. geotagging, pictures of credit cards, etc.)
  • Think about what you’re telling everyone by “checking in” on social sites.
  • Don’t overshare.
  • If you’re really serious, use anonymizers.

Another interesting battle involving issues of online privacy can be described as that of “Transparency vs Anonymity”. We can choose to write and contribute as ourselves in a completely transparent way (e.g. I am Blake here on LISNews) or to be more or less anonymous (e.g. bibiliofuture is obviously a pseudonym and chooses to remain more or less anonymous) or somewhere in between (e.g. birdie is well known to regular readers as Robin). I believe anyone should have the option to be anonymous here at LISNews. Two popular websites that serve as prime examples of this battle are Facebook and 4chan. The folks behind Facebook believe that we should always be ourselves. Facebook thinks it best we are all identifiable in what we write on the web. 4chan and its founder are strong believers in anonymity. I believe there are solid arguments on both sides of this debate:

  • When you’re really you, you’re willing/obligated to accept failure and criticism, and this will make you less likely to speak up or take controversial viewpoints, or disagree.
  • With one identity, whatever you do and whatever you say or write, is always associated with you, so it makes you accountable for your behavior, and probably prevents slander, flamewars, etc…
  • If you’re anonymous, you’re unfiltered and raw. You have expression without repercussions; it fuels creativity and experimentation, and makes what you do more authentic.
  • If you have more than one identity, or if you’re hiding behind anonymity, you’re being inauthentic and cowardly.

I won’t choose a side here, I’ll let you decide if you believe there is more good in being anonymous or transparent. For many people be anonymous, or at least using a pseudonym doesn’t mean they are trying to hide, but rather they are finally abe to be themselves. They can be real about themselves but not use their real name. Having a pseudonym, or being anonymous, allows what we say to be judged on its merit alone, with no preconseptions.

There is an arms race between those who want to track, and those of us who wish to opt-out. Who will win this race may be determined by Congress. So far, the United States has no comprehensive law protecting consumer privacy. We have a patchwork of laws, and some self-regulation. We should hope any new law would force companies to allow us to know exactly what is happening to our information. This may be changing, as a recent NYTimes Report says, the F.T.C. has endorsed a related idea — that companies collect only the data they need about people and keep it no longer than necessary. If businesses minimize data collection from the get-go, there may be less need for an eraser button later, says Jessica Rich, deputy director of the F.T.C.’s bureau of consumer protection.

I think that we, as librarians, need to consider a few questions:

Are there really new social norms now?
Are people okay with less privacy now?
Should this make any difference to your library policies?

Finally, something to think about… In theory, all your emails could become public, or are already public.

IT Security For Libraries First In A Series

IT Security In Libraries
8. Social Media Security
7. Practical IT Security
6. Integrating IT Security In Your Library
5. 20 Common Security Myths
4. How To Stay Safe Online
3. Passwords
2. Privacy
1. IT Security Foundations

Today’s post is long on theory. I’ll argue that most any library can be a target, and present some ideas on how to make things more secure in your library.
My first post will cover privacy, because I think it’s closely related to security, and it’s something we as librarians take seriously. Then I’ll cover a bunch of ways to stay safe online, how to secure your browser, PC and other things you and your patrons use every day. I’ll also cover some common security myths. Then we’ll talk passwords: everything has a password now, and I want to make sure we all understand what it takes to make your password as secure as possible. Then we’ll talk network security for a bit, followed by hardware and PC security. Then I’ll focus on security issues that you’ll find in your library. And last, but not least, some things I think you’ll find interesting that sysadmins do with servers to make things safer for you, and that you’ll never see as an end user.

One way to begin thinking about security for your library is by asking yourself few questions:

What do you have to lose?
What does your library & patrons have to lose?
What are the bad guys after?

Coming up with even a few quick answers to these questions can be helpful, I think, because it’s important to remember we all have something to lose, and that we all have a part to play in keeping ourselves and our libraries safe.

It’s also important to know that, ultimately, there is no such thing as a secure computer. Nothing we do can make things 100% safe. We can just make things safer than they were before. All of the security work we do is about reducing risk. It’s about knowing what we’re up against. We want to reduce the possible frequency of loss (by securing things as much as possible, given our resources) AND we want to reduce the potential magnitude of loss (by limiting what can be lost as much as possible).

To help set the stage for success we should keep in mind 2 things. “Any lock can be picked”, and people are the weakest link in security chain. First, people:

People choose bad passwords, we write them down, we share them, we reuse them,
People email things we shouldn’t
People post things on twitter or Facebook.
People click on links without knowing what’s behind them.
People don’t update our computers and programs.
People plug in USB drives w/o knowing where they came from.

Of course, we all want our computers to work. We don’t want to worry about all this security. We just want things to be safe. We have better things to do. We do insecure things because we’re tired and busy. We write down passwords because our brains are full. We have better things to do than update our computers and programs. It’s not (only) because people are lazy. It’s because every layer of security we add causes more work for them. Much of this advice, many of these things we want them to do just costs too much in terms of a daily burden when so few of them will really be harmed by evil doers. There is generally low motivation and poor understanding of why this could be important. People choose the easiest and quickest way to get things and hope for the best.

So even though we have better security than ever before, there are also more ways to defeat it than ever before. To make matters worse, we are now in the era of “steal everything.” We all have something a hacker is interested in stealing. And to make things even worse, barriers to this particular type of theft are lower than ever.

Frequently, hacking requires little training or knowledge or investment of time. Hackers have moved beyond banks and are now stealing more mundane things that you have. These are all worth money, or can be used to cause trouble and spread malware. There are bad guys who will pay for email passwords, Facebook logins, trojaned PCs, game logins, nearly anything you have. Our libraries are no exception. They become targets because of what we have inside our ILSs, our public access machines, the OPAC, the databases and more.

What I’m hoping to do is in this series highlight ways to help reduce your exposure. That, in itself, could help make you safer because many hackers are just looking for easy targets, and they will move on if the common security holes are closed. To beat them you need to be proactive and know how the bad guys think.

The bad guys we’re up against have many goals. Some are simply common criminals, others are spammers or doing blackhat SEO, they could be APT agents, corporate spies, or just hactivists. They are all over the world, and they are hard to find because they hide behind proxies and botnets. In a recent survey of 583 U.S companies conducted by Ponemon Research on behalf of Juniper Networks, 90 percent of the respondents said their organizations’ computers had been breached at least once by hackers over the past 12 months. Now, remember that first question I asked? About what you had to lose? Security is a real issue, and hopefully this series of posts will help you reduce your risks.

The posts will be broken up into these main topics:
-Privacy
-Staying Safe Online
-Passwords
-Network Security
-Hardware Security / PC Security
-Security In Your Library
-Server Side Security

You can check out the new posts Here and also subscribe to this topic in your feed reader Here.

Crackers still at it

One of Many Stories on the recent wave of DOS attacks on major web sites.

News.com also has a nice Wrap up story that explains how this kind of thing happens.

The weapons used to execute \”denial of service\” attacks, which crippled major Web sites this week, have existed in rudimentary form for decades. But security experts say several effective assault tools that help automate the launch of such attacks have been released only recently.

With names like Trinoo, Tribal Flood Network and Stacheldraht (German for \”barbed wire\”), these tools take advantage of otherwise innocent computers connected to the global network to launch a vast flood of traffic at their targets.

Malicious HTML

CERT has issued a Report warning internet uses of malicious HTML.

They also posted a Solution Here


A web site may inadvertently include malicious HTML tags or script in a dynamically generated page based on unvalidated input from untrustworthy sources. This can be a problem when a web server does not adequately ensure that generated pages are properly encoded to prevent unintended execution of scripts, and when input is not validated to prevent malicious HTML from being presented to the user.

CERT has issued a Report warning internet uses of malicious HTML.

They also posted a Solution Here


A web site may inadvertently include malicious HTML tags or script in a dynamically generated page based on unvalidated input from untrustworthy sources. This can be a problem when a web server does not adequately ensure that generated pages are properly encoded to prevent unintended execution of scripts, and when input is not validated to prevent malicious HTML from being presented to the user.

When a victim with scripts enabled in their browser reads this
message, the malicious code may be executed unexpectedly. Scripting
tags that can be embedded in this way include <SCRIPT>,
<OBJECT>, <APPLET>, and <EMBED>.

In addition to scripting tags, other HTML tags such as the
<FORM> tag have the potential to be abused by an attacker.