An Elephant in the Living Room

Don’t forget to lock the obvious front door to your network

• By Julie Olenski
• May 01, 2015

Security managers are more aware than ever that information security requires a layered approach with components addressing every point of intrusion on the corporate network. Yet with an estimated 196 billion emails to be sent daily worldwide in 2015 and email continuing to dominate internal network traffic at most organizations, a network security plan that fails to address the risks posed by email is like leaving the front door unlocked.

Data loss or breach is arguably the largest risk of email communication. The concern is just as great among unregulated industries as it is in sectors where privacy is of heightened concern such as in financial services and healthcare. Here are a few facts that illustrate the urgency:

• 53 percent of employees have received unencrypted, risky corporate data via emails or email attachments.
• 21 percent of employees report sending sensitive information without encryption.

The costs of data loss are staggering, not to mention the damage it does to a company’s reputation (who can forget the contents of those Sony emails?) and any legal repercussions for violating regulations regarding the transmission and storage of sensitive information such as, HIPAA, FIPPA or PCI.

• 22 percent of companies experience data loss through email each year.
• The average corporate data breach costs $3.5 million.

A growing threat to corporate email users is phishing. Sending emails from a forged sender address, called spoofing, is one way of carrying out a phishing attack, with the goal of tricking the unsuspecting recipient into downloading malware or entering confidential information into a fake web site where it is accessible to the hacker. Though it’s often viewed as a consumer problem— it seems every week there’s a new attack targeting customers of retail sites or online services—hackers have started to set their sights on corporate users by impersonating the company and targeting employees.

• An estimated 1 out of 392 emails is part of a phishing attack.
• 300 percent growth in phishing emails in the past year.
• 33 percent of Fortune 500 executives fall for phishing bait.

Digitally Signed and Encrypted Email: Network Defenses

Not surprisingly 35 percent of organizations now use encrypted email, up from 29 percent according to a Ponemon Institute report. As of this February, Google reported that 78 percent of outbound Gmail messages are encrypted.

The most common approaches to email encryption are based on public key cryptography. Google uses TLS, the same technology that secures your connection to websites (as indicated by the https and padlock in the address bar). For desktop email clients (e.g., Microsoft Outlook, Apple Mail, Thunderbird), which are often more common in corporate environments, S/MIME is the most popular option.

S/MIME, or Secure/Multipurpose Internet Mail Extensions, is the industry standard for public key encryption for MIMEbased (message-based) data. S/MIME offers two key email security functions:

• Digital Signature
• Encryption

To digitally sign and encrypt emails, you will need an S/MIME digital certificate. A digital certificate is a virtual passport; a way of proving your identity in online transactions. Just as a local government needs to verify an identity before issuing a passport, a third party verification entity known as a Certificate Authority (CA) needs to vet an individual before issuing a digital certificate. Since the certificate is unique to the individual, using it to sign an email is a way to prove, “yes, it’s really me sending this email.”

Digitally Signed Emails Mitigate Phishing

Digitally signing your emails is a way to assure recipients that the email is legitimate and actually came from you. You can see how this mitigates the corporate phishing risks discussed above. If your company standardizes on digitally signing all email communication, any spoofed emails from phishers will immediately raise a red flag since they aren’t signed.

Encrypted Emails Prevent Sensitive Data from Falling into the Wrong Hands

Encrypting an email ensures only the intended recipient can access the contents. This is because the encryption process requires information from your recipient’s digital certificate. Unless someone has access to the certificate (and only the individual should have access), he won’t be able to read the contents of the email.

One erroneous perception is that digital signatures and encryption add time. In fact, digitally signing an email is as simple as clicking a button, with many email clients enabling the user to set digital signatures as a default on all outgoing messages.

A Red-Ribbon Badge of Authenticity

Digitally signed and encrypted emails literally wear an emblem of their added security. In Microsoft Outlook, a red ribbon indicates that the email was digitally signed and the identity of the signer is listed under the subject line. Encrypted emails display a padlock.

Clicking on the red ribbon or padlock verifies the identity of the sender and offers more details about the signature. These clear trust indicators mean the recipient of the email can instantly see that the email was digitally signed or encrypted, by whom, and know that the email actually came from the correct person, has not been forged, and that the contents of the email have not been changed since it was sent.

Is It Best for Me?

Determining if an email security solution is the best fit for a given organization requires a thoughtful review of many factors:

• Do you need to send sensitive information via email?
• What types of regulations do you need to meet? (For instance, HIPAA, FIPPA, PCI regulations regarding the transmission of sensitive information)
• Has your organization been victim to email spoofing or other phishing threats?
• How does the solution authenticate the email sender?
• Does the solution ensure the contents of emails are not altered after they’re sent?
• What is the implementation process like? Will there be a burden on IT?
• Will this solution be easy for you and other end users to adopt?
• What email clients do you need to support?

With hacks, breaches and information theft rampant on corporate networks today, any approach that promises to lessen the likelihood of information loss—with minimal if any impact on end user ease and workday efficiency—is an important step toward controlling those digital assets within the corporate perimeter.

This article originally appeared in the May 2015 issue of Security Today.