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Have you ever wondered if it was safe to open a spreadsheet attached to an e-mail from a colleague, grab a cool little screen saver, or download music or video files from a stranger's computer? Well, before you do, consider the potential risks to your PC and if you're at work, the company network.
Protecting your computer from the potential dangers of downloading takes a bit of forethought and caution.
The hazards of downloading
When you transfer a file to your computer, you're downloading it. Downloading includes installing programs from a CD, opening pictures or links to websites from e-mail, copying Word documents and Excel spreadsheets from a network, upgrading software acquired from the web, or transferring music files from a computer half a world away.
If you're not careful, these files could be a vehicle for malicious software (also called malware). Malware could be installed on you PC without your knowledge or explicit consent or it could be bundled with a program you intend to download.
Another potential threat is spyware. The most common forms of spyware can change your computer's behavior — slowing it to a crawl or causing it to crash. Even more alarming, spyware can be used to track your browsing habits, steal passwords and allow an attacker to gain control of your system.
Get ready: Strengthen your computer's defenses
Start by decreasing your computer's vulnerability to outside risks. At work, keep in mind that these protections may already be in place, so check with your system administrator first before you follow any of the following instructions.
Improve your computer's overall security
- Set your antivirus program to actively scan all incoming files and e-mail attachments before you open them.
- Many e-mail programs offer spam filters that can help block unwanted messages.
- Install and run a program to help detect and remove spyware. Your company may provide an anti-spyware program on its network. If it doesn't, consider Microsoft Windows AntiSpyware or free anti-spyware software from other companies.
Keep your software safety net up to date
Spammers and attackers work relentlessly to defy computer defenses. You can help thwart them by keeping your protective software current, which can stop new attacks as they're reported.
- Visit Microsoft Update to confirm that you have Windows Automatic Updates turned on, and that you've downloaded and installed all the latest critical releases.
- Regularly download the latest anti-spyware and antivirus updates. Scan your computer right away.
- If you've installed Microsoft Office, visit Office Update regularly to make sure you have the latest security releases.
Download with caution: Think first. Click later.
Your computer should now be well-defended, although no technology can protect it against every danger. And that's where you come in.
Consider the following list before you click an attachment (or link) in an e-mail or instant message, download a file from a website (or a pop-up ad), or share music or other files from a stranger's computer.
1. Pause before you open attachments and click links
- Never open attachments in e-mail or instant messages from strangers. If you know the sender, but the message arouses your suspicions, check before you open the attachment.
- Don't click links in e-mail or instant messages. (If you know the sender, check before you click.) The same goes for pop-up windows and banner ads.
- Do not click Agree, OK or I accept to get rid of a pop-up advertisement, an unexpected warning or even an offer to remove spyware. Instead, close the window by clicking the X in the upper-right corner of the dialogue box or by pressing Alt+F4.
2. Download from reputable sites
Not every Internet neighborhood is safe. Be cautious about downloading from a website if you were referred there by e-mail from an unknown source. Also be wary if the site contains objectionable material, makes offers that seem too good to be true or does not include a clearly written privacy statement.
3. Respect the law
Illegal downloads could have negative consequences for your company. For example, if you use pirated software on your company's computer, the company may be held liable.
4. Install and use file-sharing programs cautiously
When you use file-sharing (also known as peer-to-peer or P2P) programs to trade music, video and other files on the web, you make some of your files available to others using similar software. Of particular concern to your company, if you're doing this at work, is that some programs share your entire hard disk drive by default, which makes anything there, including confidential corporate or personal content, available to anyone using the program. Using some file-sharing programs can also mean leaving an open back door to your computer while it's connected to the Internet.
File-sharing programs have other risks. The programs can themselves be purveyors of malware. Or, they may lead you to unwittingly download something that is illegal, such as a copyrighted song or certain kinds of pornography. Any of these programs could also put your company's network at risk. After it is installed on your computer, some software can be exceedingly tough to remove (assuming you can even find it).
5. Follow the rules of your company's acceptable use policy
Many companies have very specific rules about what you can and cannot download onto office computers and there may be penalties for violating these rules.
How to save a file for safer download
If your computer's defenses are current and active, and you're convinced the file you're about to download is legitimate, then you're ready to download. Before you open a file or install a program, follow these directions to save it to your hard disk drive. That way, your antivirus software can check the file and delete it if it detects potentially damaging code.
- Save all your work to help avoid losing data in case a problem occurs. Installing some software programs can erase data on a computer (though not always intentionally).
- Double-click the link or the file to start the download. If you're downloading a document, you'll see an Open button instead of Run.
- If you have any doubt at all about the file, click Save. Indicate where you want to save it > Save.
- After you've saved the file to your hard disk drive, double-click it to open or run it. If your antivirus program detects a virus, do not continue. Delete the file from your hard disk drive.
- Internet Explorer displays one last warning. Click Run only if you have absolute trust in the source of the download. Click the publisher name to check for a valid digital signature. If you cannot click the name, the file has not been digitally signed.
- If you see "The digital signature is OK," click OK > Run. If you do not see this sentence, you can't be sure either of the source or that the file has not been tampered with since it was published. Click Run only if you have absolute trust in the source of the download.
- Carefully read the license agreement, and if you agree with the terms, click I agree. Surprisingly, programs bundled with spyware, for example, will often specify in the license agreement that they will monitor your surfing habits or display advertisements. When you click "I agree," you're giving the software publishers permission to track your computer on the web or display ads.
- Follow the directions on your screen if you are installing a program.
Be more cautious with certain file types
Although no type of file is perfectly safe, pictures, music and text files with names ending in .JPG, .GIF, .MP3, or .TXT are less likely to be harmful. Be extra cautious with all other file types. Files with names ending in .EXE, .COM, .BAT, and .VBS in particular can contain code, which if harmful, could damage your system.
Adapted from an original piece from Microsoft At Work.
Published October 2006
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