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Using Caution with Email Attachments

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.

How 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
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

Evaluating Your Web Browser's Security Settings

Check the security settings in your web browser to make sure they are at an appropriate level. While increasing your security may affect the functionality of some web sites, it could prevent you from being attacked

Why are security settings for web browsers important?

Your web browser is your primary connection to the rest of the internet, and multiple applications may rely on your browser, or elements within your browser, to function. This makes the security settings within your browser even more important. Many web applications try to enhance your browsing experience by enabling different types of functionality, but this functionality might be unnecessary and may leave you susceptible to being attacked. The safest policy is to disable the majority of those features unless you decide they are necessary. If you determine that a site is trustworthy, you can choose to enable the functionality temporarily and then disable it once you are finished visiting the site.

Where can you find the settings?

Each web browser is different, so you may have to look around. For example, in Internet Explorer, you can find them by clicking Tools on your menu bar, selecting Internet Options..., choosing the Security tab, and clicking the Custom Level... button. However, in Mozilla, you click Edit on the menu bar, select Preferences..., and click the + next to Privacy & Security to explore the various options. Browsers have different security options and configurations, so familiarize yourself with the menu options, check the help feature, or refer to the vendor's web site.

While every application has settings that are selected by default, you may discover that your browser also has predefined security levels that you can select. For example, Internet Explorer offers custom settings that allow you to select a particular level of security; features are enabled or disabled based on your selection. Even with these guides, it is helpful to have an understanding of what the different terms mean so that you can evaluate the features to determine which settings are appropriate for you.

How do you know what your settings should be?

Ideally, you would set your security for the highest level possible. However, restricting certain features may limit some web pages from loading or functioning properly. The best approach is to adopt the highest level of security and only enable features when you require their functionality.

What do the different terms mean?

Different browsers use different terms, but here are some terms and options you may find:

• Zones - Your browser may give you the option of putting web sites into different segments, or zones, and allow you to define different security restrictions for each zone.
For example, Internet Explorer identifies the following zones:
• Internet - This is the general zone for all public web sites. When you browse the internet, the settings for this zone are automatically applied to the sites you visit. To give you the best protection as you browse, you should set the security to the highest level; at the very least, you should maintain a medium level.
• Local intranet - If you are in an office setting that has its own intranet, this zone contains those internal pages. Because the web content is maintained on an internal web server, it is usually safe to have less restrictive settings for these pages. However, some viruses have tapped into this zone, so be aware of what sites are listed and what privileges they are being given.
• Trusted sites - If you believe that certain sites are designed with security in mind, and you feel that content from the site can be trusted not to contain malicious materials, you can add them to your trusted sites and apply settings accordingly. You may also require that only sites that implement Secure Sockets Layer (SSL) can be active in this zone. This permits you to verify that the site you are visiting is the site that it claims to be. This is an optional zone but may be useful if you personally maintain multiple web sites or if your organization has multiple sites. Even if you trust them, avoid applying low security levels to external sites-if they are attacked, you might also become a victim.
• Restricted sites - If there are particular sites you think might not be safe, you can identify them and define heightened security settings. Because the security settings may not be enough to protect you, the best precaution is to avoid navigating to any sites that make you question whether or not they're safe.
• JavaScript - Some web sites rely on web scripts such as JavaScript to achieve a certain appearance or functionality, but these scripts may be used in attacks.
• Java and ActiveX controls - These programs are used to develop or execute active content that provides some functionality, but they may put you at risk.
• Plug-ins - Sometimes browsers require the installation of additional software known as plug-ins to provide additional functionality. Like Java and ActiveX controls, plug-ins may be used in an attack, so before installing them, make sure that they are necessary and that the site you have to download them from is trustworthy.

You may also find options that allow you to take the following security measures:

• Manage cookies - You can disable, restrict, or allow cookies as appropriate. Generally, it is best to disable cookies and then enable them if you visit a site you trust that requires them
• Block pop-up windows - Although turning this feature on could restrict the functionality of certain web sites, it will also minimize the number of pop-up ads you receive, some of which may be malicious.

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