Original URL: http://www.theregister.co.uk/2007/09/17/whole_journey_email_encryption/

The importance of 'whole journey' email encryption

Leave no weak spots

By Nigel Stanley

Posted in Security, 17th September 2007 10:27 GMT

It is very rare for an organisation to mandate less security in its IT systems. In fact, the relentless march of new threats places pressure on us all to increase our levels of security, to ensure we can match new and emerging attacks.

Email is one of the most potent business tools that we have, but also one of the most vulnerable systems for attack.

The volume of organisational "smarts" that can travel out of the virtual front door (or the back door from rogue inside abuse) via email can be staggering. Quotes, legal information, contracts, customer data and just about every type of document you can think of will be transported via email.

After all, traditional "snail mail" is all but dead for day to day commercial communications.

Securing email systems must be at the top of any corporate security expert's to-do list, but as with most IT problems there are many different approaches you can take.

One interesting debate is that of precisely when and where to encrypt your email traffic. Is it at the client or is it at the gateway prior to sending to the recipient? Or maybe the encryption is only from the gateway to the recipient client?

From gateway to gateway

The majority of organisations are happy with the placing of an email gateway of some description that encrypts messages as they leave the corporate perimeter. These gateways are often appliances that process emails as they leave and enter the organisation as well as providing anti-malware support.

The problem with email gateway encryption is that emails are not encrypted until they get to the gateway. In other words, the gateway does not protect internal email or email that is travelling from the internal network towards the gateway. These emails will travel around the internal organisation network unencrypted and in plain text, vulnerable to prying malware or internal monitoring and snooping devices.

Some organisations may be comfortable with this, but those needing a higher level of email security need to look a bit deeper.

Why?

Well, malicious insiders will often make a point of going after internal email traffic as this is often seen as a soft target. In a large organisation thousands of plain text emails can be moving around the organisation at any moment in time. These can be accessible to anyone motivated enough to run a sniffing device on the network, and certainly any prying email systems administrator would have unfettered access. Even if an email is worthless outside an organisation, internally it may be priceless and cause significant controversy if its contents were revealed. Examples would include emails discussing redundancies and pay rises for a start.

Most vulnerable to outside interference would be the ubiquitous mobile user with a handheld device. Tour any financial centre and see the thousands of city whizz-kids passing data around in email form, with goodness knows what data being passed in plain text. Unless emails are secured before they leave a handheld device, organisations leave a big gap in their security measures here.

By focusing solely on email gateway to gateway encryption, users risk exposing themselves to unnecessary risk of email intrusion.

From end point to end point

A more suitable encryption option would be to put in place a security technology that requires all messages to be encrypted at the time they are sent from a client - any client. That way there would never be insecure email traffic, as we would have whole journey encryption for each and every email being sent.

A problem with this approach is how to make the email encryption seamless to the user. Asking users to manually encrypt emails each time they are sent is a surefire recipe for wasted investment in security technology.

By using software that integrates into the heart of an email system, as well as an existing directory structure, user intervention is not required and system management is made a lot easier.

Make it so

If you work in an organisation that handles sensitive data then email encryption is a must-have.

The only appropriate way to secure such traffic must be on an end point to end point (client to client) basis. Anything else leaves you subject to a potential security violation. The implementation of a client-to-client solution need not be onerous, and you would expect a top flight vendor to have a product that would interoperate with your current email system and provide the tools and infrastructure to enable quick deployment and management across a desktop estate.

This solution must also have the capability to reflect organisational security policies in the emails being sent, for example picking up keywords, sender details or recipient information, and then applying an appropriate level of encryption based on relevant sensitivities. An email client encryption product that is also extensible enough to take part in an enterprise encryption strategy is a real bonus.

Providing security for email traffic is now crucial for any business, and deploying a flexible encryption solution is essential.

Gateway to gateway email security might be fine for some organisations, but end point to end point whole journey email security is the only dependable way of completely securing corporate smarts on the move.

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