Many of the warning phrases you probably heard from your parents and teachers are also applicable to using computers and the internet.

Why are these warnings important?
Like the real world, technology and the internet present dangers as well as benefits. Equipment fails, attackers may target you, and mistakes and poor judgment happen. Just as you take precautions to protect yourself in the real world, you need to take precautions to protect yourself online. For many users, computers and the internet are unfamiliar and intimidating, so it is appropriate to approach them the same way we urge children to approach the real world.
What are some warnings to remember?

• Don’t trust candy from strangers - Finding something on the internet does not guarantee that it is true. Anyone can publish information online, so before accepting a statement as fact or taking action, verify that the source is reliable. It is also easy for attackers to “spoof” email addresses, so verify that an email is legitimate before opening an unexpected email attachment or responding to a request for personal information (see Using Caution with Email Attachments and Avoiding Social Engineering and Phishing Attacks for more information).
  
• If it sounds too good to be true, it probably is - You have probably seen many emails promising fantastic rewards or monetary gifts. However, regardless of what the email claims, there are not any wealthy strangers desperate to send you money. Beware of grand promises—they are most likely spam, hoaxes, or phishing schemes (see Reducing Spam, Identifying Hoaxes and Urban Legends, and Avoiding Social Engineering and Phishing Attacks for more information). Also be wary of pop-up windows and advertisements for free downloadable software—they may be disguising spyware (see Recognizing and Avoiding Spyware for more information).
• Don’t advertise that you are away from home - Some email accounts, especially within an organization, offer a feature (called an autoresponder) that allows you to create an “away” message if you are going to be away from your email for an extended period of time. The message is automatically sent to anyone who emails you while the autoresponder is enabled. While this is a helpful feature for letting your contacts know that you will not be able to respond right away, be careful how you phrase your message. You do not want to let potential attackers know that you are not home, or, worse, give specific details about your location and itinerary. Safer options include phrases such as “I will not have access to email between [date] and [date].” If possible, also restrict the recipients of the message to people within your organization or in your address book. If your away message replies to spam, it only confirms that your email account is active. This may increase the amount of spam you receive (see Reducing Spam for more information).
• Lock up your valuables - If an attacker is able to access your personal data, he or she may be able to compromise or steal the information. Take steps to protect this information by following good security practices (see the Cyber Security Tips index page for a list of relevant documents). Some of the most basic precautions include locking your computer when you step away; using firewalls, anti-virus software, and strong passwords; installing appropriate patches; and taking precautions when browsing or using email.
• Have a backup plan - Since your information could be lost or compromised (due to an equipment malfunction, an error, or an attack), make regular backups of your information so that you still have clean, complete copies (see Good Security Habits for more information). Backups also help you identify what has been changed or lost. If your computer has been infected, it is important to remove the infection before resuming your work (see Recovering from Viruses, Worms, and Trojan Horses for more information). Keep in mind that if you did not realize that your computer was infected, your backups may also be compromised.

You may think that you are anonymous as you browse web sites, but pieces of information about you are always left behind. You can reduce the amount of information revealed about you by visiting legitimate sites, checking privacy policies, and minimizing the amount of personal information you provide.

What information is collected?

When you visit a web site, a certain amount of information is automatically sent to the site. This information may include the following:

• IP address - Each computer on the internet is assigned a specific, unique IP (internet protocol) address. Your computer may have a static IP address or a dynamic IP address. If you have a static IP address, it never changes. However, some ISPs own a block of addresses and assign an open one each time you connect to the internet—this is a dynamic IP address. You can determine your computer’s IP address at any given time by visiting www.showmyip.com
• Domain name - The internet is divided into domains, and every user’s account is associated with one of those domains. You can identify the domain by looking at the end of URL; for example, .edu indicates an educational institution, .gov indicates a US government agency, .org refers to organization, and .com is for commercial use. Many countries also have specific domain names. The list of active domain names is available from the Internet Assigned Numbers Authority (IANA).
• Software details - It may be possible for an organization to determine which browser, including the version, that you used to access its site. The organization may also be able to determine what operating system your computer is running.
• Page visits - Information about which pages you visited, how long you stayed on a given page, and whether you came to the site from a search engine is often available to the organization operating the web site.

If a web site uses cookies, the organization may be able to collect even more information, such as your browsing patterns, which include other sites you’ve visited. If the site you’re vising is malicious, files on your computer, as well as passwords stored in the temporary memory, may be at risk.
How is this information used?

Generally, organizations use the information that is gathered automatically for legitimate purposes, such as generating statistics about their sites. By analyzing the statistics, the organizations can better understand the popularity of the site and which areas of content are being accessed the most. They may be able to use this information to modify the site to better support the behavior of the people visiting it.

Another way to apply information gathered about users is marketing. If the site uses cookies to determine other sites or pages you have visited, it may use this information to advertise certain products. The products may be on the same site or may be offered by partner sites.

However, some sites may collect your information for malicious purposes. If attackers are able to access files, passwords, or personal information on your computer, they may be able to use this data to their advantage. The attackers may be able to steal your identity, using and abusing your personal information for financial gain. A common practice is for attackers to use this type of information once or twice, then sell or trade it to other people. The attackers profit from the sale or trade, and increasing the number of transactions makes it more difficult to trace any activity back to them. The attackers may also alter the security settings on your computer so that they can access and use your computer for other malicious activity.
Are you exposing any other personal information?

While using cookies may be one method for gathering information, the easiest way for attackers to get access to personal information is to ask for it. By representing a malicious site as a legitimate one, attackers may be able to convince you to give them your address, credit card information, social security number, or other personal data (see Avoiding Social Engineering and Phishing Attacks for more information).
How can you limit the amount of information collected about you?

• Be careful supplying personal information - Unless you trust a site, don’t give your address, password, or credit card information. Look for indications that the site uses SSL to encrypt your information (see Protecting Your Privacy for more information). Although some sites require you to supply your social security number (e.g., sites associated with financial transactions such as loans or credit cards), be especially wary of providing this information online.
• Limit cookies - If an attacker can access your computer, he or she may be able to find personal data stored in cookies. You may not realize the extent of the information stored on your computer until it is too late. However, you can limit the use of cookies (see Browsing Safely: Understanding Active Content and Cookies for more information).
• Browse safely - Be careful which web sites you visit; if it seems suspicious, leave the site. Also make sure to take precautions by increasing your security settings (see Evaluating Your Web Browser’s Security Settings for more information), keeping your virus definitions up to date (see Understanding Anti-Virus Software for more information), and scanning your computer for spyware (see Recognizing and Avoiding Spyware for more information).