December ISAC Security Newsletter

The Internet is arguably one of the greatest wonders of the world. We shop, get our news, play games, conduct research, keep in touch and do so much more on the Internet, all through a web-browser. Recent news about a major vulnerability in Internet Explorer, the world’s most popular web browser, reminds us all of the risk we run while online, but like the proverbial genii let out of the bottle, we can not retreat back to the days before the Internet played such a major role in our lives. In this month’s newsletter we will discuss what pop-ups are and what you can do to keep them from affecting the security of your computer and data.
What are Pop-Ups?
Pop-ups are often used for advertising, to entice you to click on the pop-up ad. Pop-ups can also be used in other ways, such as on a “Help” section of an online form.  The pop-up can be read without interfering with the form or page you are already visiting.  This technique, for example, could be used on banking or ecommerce sites so as to not interfere with the current transaction or form request.

Occasionally you may encounter a “pop-under” which instead of opening on top of whatever website you are viewing it will open underneath the current web page. That way when you close your browser window you’ll be greeted with an unexpected window.

While there are legitimate uses for pop-ups, they can also be used maliciously to entice you to click the pop-up window, which then downloads spyware or malicious code without your knowledge.  These kinds of pop-ups often claim to “detect a virus on your computer” or claim to be a “spyware alert!” or offer a “free product” such as laptop or an anti-virus program.

Usually pop-ups are executed through JavaScript, a very popular way of adding content to websites.  They can also be executed through online flash programs, though these are more difficult to stop.
What if I encounter pop ups when I am not browsing the Internet?
If you encounter pop-ups, especially an endless stream of them, it is an indication your computer is possibly infected with spyware or a computer virus.

How can you protect yourself against unwanted or malicious pop-ups?

Most Internet browsers include pop-up blockers. They also have a setting to either completely disable JavaScript (and therefore most pop-ups) or to only allow JavaScript with the user’s permission (prompting).  Both methods can usually stop advertising and malicious pop-ups.  However, Disabling JavaScript (whether via your browser or another program) can interfere with the “look and feel” or even functionality of a legitimate web site including some functions of WebSIS or Banner. Luckily, most browsers now allow you to select websites to permit pop-ups from, and for how long (during the given session, one time or permanently).  In general, we recommend that you:

• Use the pop-up blocking feature in Internet Explorer or ay browser you use.
• Consider setting your computer to the “Prompt” setting you before enabling Java scripting.
• Never click inside the pop-up window to close it, even if it has a button or tab that says “Close,” “No Thank You,” or anything else.  Instead, either click on the “X” at the top right corner of the title bar, or depending on your browser or operating system you can hold down the “Alt” key then press “F4” to close the currently opened window
• Browse as a non-privileged user (one without administrative privileges) to diminish the effects of a successful attack.  This means you should login to your computer as non-administrative user whenever possible.
• Update your operating system and web browser software. Use Windows XP Service Pack 3 or Windows Vista Service Pack 1 or later, and Use Internet Explorer 7 or later, Firefox 3.0.5 etc.
• Set your browser security to at least “Medium” to help detect unauthorized downloads.
• Use anti-virus and anti-spyware software, and a firewall, and update them all regularly. Avoid disabling anti-virus software on your computer for any reason.
• Avoid visiting strange website or clicking on links in strange emails.
• Avoid downloading anything from strange or website involved in any illegal activity. Criminals are always lurking at illegal sites and often plant malwares in seemingly innocuous downloads such as free software or free (or even illegal) music or video.

For additional information on pop-ups and browser protection, go to:
•    Web Browser Attacks: www.msisac.org/awareness/news/2008-07.cfm
•    Browsing Safely: Understanding Active Content and Cookies: www.us-cert.gov/cas/tips/ST04-012.html
•    Evaluating Your Web Browser’s Security Settings: www.us-cert.gov/cas/tips/ST05-001.html
•    Spyware: www.onguardonline.gov/topics/spyware.aspx

Brought to you in conjunction with :    http://www.msisac.org