Be Cautious with Email Attachments

Email attachments can present a serious threat to you your organization. Why is this?

Email attachments are a popular and convenient way to send documents, but 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.

Some of the characteristics that make email attachments convenient and popular are also the ones that make them a common tool for hackers:

  • 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 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 of software in email.
  • Keep software up to date – Install software patches so that attackers can’t take advantage of known problems or vulnerabilities. Many operating systems offer automatic updates. If this option is available, you should enable it.
  • Save and scan any attachments before opening them – If you must 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 disk.
  3. Manually scan the file using your anti-virus software.
  4. If the file is clean and doesn’t seem suspicious, go ahead and open it.
  • 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 creating separate accounts on your computer – Most operating systems give you the option of creating multiple user accounts with different privileges. Consider reading your email on an account with restricted privileges. Some viruses need “administrator” privileges to infect a computer.
  • Apply additional security patches – You may be able to filter certain types of attachments through your email (spam filter) or a firewall.

More cyber security tips can be found at:  https://www.us-cert.gov/ncas/tips/ST04-010

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