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 have been exposed to internationalized domain names (IDNs) without realizing it. While they typically do not affect your browsing activity, IDNs may give attackers an opportunity to redirect you to a malicious web page.

What are internationalized domain names?
To decrease the amount of confusion surrounding different languages, there is a standard for domain names within web browsers. Domain names are included in the URL (or web address) of web site. This standard is based on the Roman alphabet (which is used by the English language), and computers convert the various letters into numerical equivalents. This code is known as ASCII (American Standard Code for Information Interchange). However, other languages include characters that do not translate into this code, which is why internationalized domain names were introduced.

To compensate for languages that incorporate special characters (such as Spanish, French or German) or rely completely on character representation (such as Asian or Arabic languages), a new system had to be developed. In this new system, the base URL (which is usually the address for the home page) is dissected and converted into a format that is compatible with ASCII. The resulting URL (which contains the string “xn--” as well as a combination of letters and numbers) will appear in your browser’s status bar. In newer versions of many browsers, it will also appear in the address bar.
What are some security concerns?

Attackers may be able to take advantage of internationalized domain names to initiate phishing attacks (see Avoiding Social Engineering and Phishing Attacks for more information). Because there are certain characters that may appear to be the same but have different ASCII codes (for example, the Cyrillic “a” and the Latin “a”), an attacker may be able to “spoof” a web page URL. Instead of going to a legitimate site, you may be directed to a malicious site, which could look identical to the real one. If you submit personal or financial information while on the malicious site, the attacker could collect that information and then use and/or sell it.
How can you protect yourself?

• Type a URL instead of following a link - Typing a URL into a browser rather than clicking a link within a web page or email message will minimize your risk. By doing this, you are more likely to visit the legitimate site rather than a malicious site that substitutes similar-looking characters.
  
• Keep your browser up to date - Older versions of browsers made it easier for attackers to spoof URLs, but most newer browsers incorporate certain protections. Instead of displaying the URL that you “think” you are visiting, most browsers now display the converted URL with the “xn--” string.
• Check your browser’s status bar - If you move your mouse over a link on a web page, the status bar of your browser will usually display the URL that the link references. If you see a URL that has an unexpected domain name (such as one with the “xn--” string mentioned above), you have likely encountered an internationalized domain name. If you were not expecting an internationalized domain name or know that the legitimate site should not need one, you may want to reconsider visiting the site. Browsers such as Mozilla and Firefox include an option in their security settings about whether to allow the status bar text to be modified. To prevent attackers from taking advantage of JavaScript to make it appear that you are on a legitimate site, you may want to make sure this option is not enabled.

Encrypting data is a good way to protect sensitive information. It ensures that the data can only be read by the person who is authorized to have access to it.

What is encryption?

In very basic terms, encryption is a way to send a message in code. The only person who can decode the message is the person with the correct key; to anyone else, the message looks like a random series of letters, numbers, and characters.

Encryption is especially important if you are trying to send sensitive information that other people should not be able to access. Because email messages are sent over the internet and might be intercepted by an attacker, it is important to add an additional layer of security to sensitive information.

How is it different from digital signatures?
Like digital signatures, public-key encryption utilizes software such as PGP, converts information with mathematical algorithms, and relies on public and private keys, but there are differences:

• The purpose of encryption is confidentiality—concealing the content of the message by translating it into a code. The purpose of digital signatures is integrity and authenticity—verifying the sender of a message and indicating that the content has not been changed. Although encryption and digital signatures can be used independently, you can also sign an encrypted message.
• When you sign a message, you use your private key, and anybody who has your public key can verify that the signature is valid. When you encrypt a message, you use the public key for the person you’re sending it to, and his or her private key is used to decrypt the message. Because people should keep their private keys confidential and should protect them with passwords, the intended recipient should be the only one who is able to view the information.

How does encryption work?

1. Obtain the public key for the person you want to be able to read the information. If you get the key from a public key ring, contact the person directly to confirm that the series of letters and numbers associated with the key is the correct fingerprint.
2. Encrypt the email message using their public key. Most email clients have a feature to easily perform this task.
3. When the person receives the message, he or she will be able to decrypt it.