While email attachments are a popular and convenient way to send documents, they are also a common source of viruses. Use caution when opening attachments, even if they appear to have been sent by someone you know.

Why can email attachments be dangerous?
Some of the characteristics that make email attachments convenient and popular are also the ones that make them a common tool for attackers:

• Email is easily circulated - Forwarding email is so simple that viruses can quickly infect many machines. Most viruses don’t even require users to forward the email—they scan a users’ computer for email addresses and automatically send the infected message to all of the addresses they find. Attackers take advantage of the reality that most users will automatically trust and open any message that comes from someone they know.
• Email programs try to address all users’ needs - Almost any type of file can be attached to an email message, so attackers have more freedom with the types of viruses they can send.
• Email programs offer many “user-friendly” features - Some email programs have the option to automatically download email attachments, which immediately exposes your computer to any viruses within the attachments.

What steps can you take to protect yourself and others in your address book?

• Be wary of unsolicited attachments, even from people you know - Just because an email message looks like it came from your mom, grandma, or boss doesn’t mean that it did. Many viruses can “spoof” the return address, making it look like the message came from someone else. If you can, check with the person who supposedly sent the message to make sure it’s legitimate before opening any attachments. This includes email messages that appear to be from your ISP or software vendor and claim to include patches or anti-virus software. ISPs and software vendors do not send patches or software in email.
• Save and scan any attachments before opening them - If you have to open an attachment before you can verify the source, take the following steps:
  1. Be sure the signatures in your anti-virus software are up to date (see Understanding Anti-Virus Software for more information)
  2. Save the file to your computer or a disk
  3. Manually scan the file using your anti-virus software
  4. Open the file
• Turn off the option to automatically download attachments - To simplify the process of reading email, many email programs offer the feature to automatically download attachments. Check your settings to see if your software offers the option, and make sure to disable it.
• Consider additional security practices - You may be able to filter certain types of attachments through your email software

The popularity of social networking sites continues to increase, especially among teenagers and young adults. The nature of these sites introduces security risks, so you should take certain precautions.

What are social networking sites?
Social networking sites, sometimes referred to as “friend-of-a-friend” sites, build upon the concept of traditional social networks where you are connected to new people through people you already know. The purpose of some networking sites may be purely social, allowing users to establish friendships or romantic relationships, while others may focus on establishing business connections.

Although the features of social networking sites differ, they all allow you to provide information about yourself and offer some type of communication mechanism (forums, chat rooms, email, instant messenger) that enables you to connect with other users. On some sites, you can browse for people based on certain criteria, while other sites require that you be “introduced” to new people through a connection you share. Many of the sites have communities or subgroups that may be based on a particular interest.
What security implications do these sites present?
Social networking sites rely on connections and communication, so they encourage you to provide a certain amount of personal information. When deciding how much information to reveal, people may not exercise the same amount of caution as they would when meeting someone in person because

• the internet provides a sense of anonymity
• the lack of physical interaction provides a false sense of security
• they tailor the information for their friends to read, forgetting that others may see it
• they want to offer insights to impress potential friends or associates

While the majority of people using these sites do not pose a threat, malicious people may be drawn to them because of the accessibility and amount of personal information that’s available. The more information malicious people have about you, the easier it is for them to take advantage of you. Predators may form relationships online and then convince unsuspecting individuals to meet them in person. That could lead to a dangerous situation. The personal information can also be used to conduct a social engineering attack (see Avoiding Social Engineering and Phishing Attacks for more information). Using information that you provide about your location, hobbies, interests, and friends, a malicious person could impersonate a trusted friend or convince you that they have the authority to access other personal or financial data.

Additionally, because of the popularity of these sites, attackers may use them to distribute malicious code. Sites that offer applications developed by third parties are particularly susceptible. Attackers may be able to create customized applications that appear to be innocent while infecting your computer without your knowledge.

How can you protect yourself?

• Limit the amount of personal information you post - Do not post information that would make you vulnerable, such as your address or information about your schedule or routine. If your connections post information about you, make sure the combined information is not more than you would be comfortable with strangers knowing. Also be considerate when posting information, including photos, about your connections.
• Remember that the internet is a public resource - Only post information you are comfortable with anyone seeing. This includes information and photos in your profile and in blogs and other forums. Also, once you post information online, you can’t retract it. Even if you remove the information from a site, saved or cached versions may still exist on other people’s machines (see Guidelines for Publishing Information Online for more information).
• Be wary of strangers - The internet makes it easy for people to misrepresent their identities and motives (see Using Instant Messaging and Chat Rooms Safely for more information). Consider limiting the people who are allowed to contact you on these sites. If you interact with people you do not know, be cautious about the amount of information you reveal or agreeing to meet them in person.
• Be skeptical - Don’t believe everything you read online. People may post false or misleading information about various topics, including their own identities. This is not necessarily done with malicious intent; it could be unintentional, an exaggeration, or a joke. Take appropriate precautions, though, and try to verify the authenticity of any information before taking any action.
• Evaluate your settings - Take advantage of a site’s privacy settings. The default settings for some sites may allow anyone to see your profile. You can customize your settings to restrict access to only certain people. However, there is a risk that even this private information could be exposed, so don’t post anything that you wouldn’t want the public to see. Also, be cautious when deciding which applications to enable, and check your settings to see what information the applications will be able to access.
• Use strong passwords - Protect your account with passwords that cannot easily be guessed (see Choosing and Protecting Passwords for more information). If your password is compromised, someone else may be able to access your account and pretend to be you.
• Check privacy policies - Some sites may share information such as email addresses or user preferences with other companies. This may lead to an increase in spam (see Reducing Spam for more information). Also, try to locate the policy for handling referrals to make sure that you do not unintentionally sign your friends up for spam. Some sites will continue to send email messages to anyone you refer until they join.
• Use and maintain anti-virus software - Anti-virus software recognizes most known viruses and protects your computer against them, so you may be able to detect and remove the virus before it can do any damage (see Understanding Anti-Virus Software for more information). Because attackers are continually writing new viruses, it is important to keep your definitions up to date.

There are some simple habits you can adopt that, if performed consistently, may dramatically reduce the chances that the information on your computer will be lost or corrupted.

How can you minimize the access other people have to your information?
You may be able to easily identify people who could, legitimately or not, gain physical access to your computer—family members, roommates, co-workers, members of a cleaning crew, and maybe others. Identifying the people who could gain remote access to your computer becomes much more difficult. As long as you have a computer and connect it to a network, you are vulnerable to someone or something else accessing or corrupting your information; however, you can develop habits that make it more difficult.

• Lock your computer when you are away from it. Even if you only step away from your computer for a few minutes, it’s enough time for someone else to destroy or corrupt your information. Locking your computer prevents another person from being able to simply sit down at your computer and access all of your information.
• Disconnect your computer from the Internet when you aren’t using it. The development of technologies such as DSL and cable modems have made it possible for users to be online all the time, but this convenience comes with risks. The likelihood that attackers or viruses scanning the network for available computers will target your computer becomes much higher if your computer is always connected. Depending on what method you use to connect to the Internet, disconnecting may mean ending a dial-up connection, turning off your computer or modem, or disconnecting cables.
• Evaluate your security settings. Most software, including browsers and email programs, offers a variety of features that you can tailor to meet your needs and requirements. Enabling certain features to increase convenience or functionality may leave you more vulnerable to being attacked. It is important to examine the settings, particularly the security settings, and select options that meet your needs without putting you at increased risk. If you install a patch or a new version of the software, or if you hear of something that might affect your settings, reevaluate your settings to make sure they are still appropriate (see Understanding Patches, Safeguarding Your Data, and Evaluating Your Web Browser’s Security Settings for more information).

What other steps can you take?
Sometimes the threats to your information aren’t from other people but from natural or technological causes. Although there is no way to control or prevent these problems, you can prepare for them and try to minimize the damage.

• Protect your computer against power surges. Aside from providing outlets to plug in your computer and all of its peripherals, some power strips protect your computer against power surges. Many power strips now advertise compensation if they do not effectively protect your computer. During a lightning storm or construction work that increases the odds of power surges, consider shutting your computer down and unplugging it from all power sources. Power strips alone will not protect you from power outages, but there are products that do offer an uninterruptible power supply when there are power surges or outages.
• Back up all of your data. Whether or not you take steps to protect yourself, there will always be a possibility that something will happen to destroy your data. You have probably already experienced this at least once— losing one or more files due to an accident, a virus or worm, a natural event, or a problem with your equipment. Regularly backing up your data on a CD or network reduces the stress and other negative consequences that result from losing important information (see Real-World Warnings Keep You Safe Online for more information). Determining how often to back up your data is a personal decision. If you are constantly adding or changing data, you may find weekly backups to be the best alternative; if your content rarely changes, you may decide that your backups do not need to be as frequent. You don’t need to back up software that you own on CD-ROM or DVD-ROM—you can reinstall the software from the original media if necessary.