What the [bleep] is DMARC?

Dane Meah

Blog

19 November 2017

As more and more businesses embark on digital transformation, the need to secure the #1 digital communication channel is a must.

SMTP or more commonly known as “Email” was created in the 1970’s with little consideration for the scale and use that it has today. The notion that nearly all business communication would be via this channel just wasn’t a consideration… The Email protocol that we know and love, for many businesses, works in a fundamentally similar way today, as it was nearly 50 years ago.

To put that in perspective of what the world was like back when email was invented, here’s a 1970’s computer.

Coming forward to today, cybercriminals are well-aware of the gaps that exist in email and are fruitfully exploiting this with huge sums of money being stolen in the process.

Email could also be likened to the Wild West, where in the most part there is little control or safety for anyone sending or receiving emails. Which emails can be trusted? How do you know which emails are genuine and which ones are out to defraud you?

Like any good Western there’s a hero and this story is no different…. introducing “DMARC”. Or the rather less catchy sounding “Domain-based, Messaging, Authentication, Reporting and Conformance” framework.

DMARC was created following a collaboration of leading companies who shared one common goal- to solve Email Fraud. These companies came from three distinct groups:

1. Major email receivers (e.g. Microsoft, Yahoo, Google)
2. Major email senders (e.g JP Morgan, Facebook, PayPal)
3. Major email vendors (e.g. Agari, Cloudmark)

Previous attempts to solve email fraud have included creation of the open standards SPF in 2002 and DKIM in 2004, respectively. In addition a litany of “fraud alert”, honeypot, brand monitoring and forensic services alongside reactive take down offerings have existed. However, none of this completely addressed the problem of Email Fraud.
DMARC was the love-child borne from cyber security collaboration at its best. It combines the best of SPF, DKIM and email monitoring by overlaying SPF/DKIM with reporting and conformance framework that allows an organisation to get eyes on their good AND bad senders, with actionable failure samples to enhance the response to why good emails are failing and the nature of the bad emails.
Here are three of the key things that DMARC will do:

1. SPF and DKIM have inherent flaws and failure scenarios which can render them ineffective (and arguably risky when used in isolation). However, the failure scenarios for DKIM and SPF do not often overlap. This allows, with a high degree of accuracy, for DMARC to make an accurate conviction based on assessing both protocols side by side, as opposed to singularly.
2. Unlike SPF or DKIM, DMARC provides you with a choice of what happens when an authentication failure occurs. As mentioned in point 1, this conviction is made upon verifying both protocols and the action can either “none”(no action),“quarantine” (quarantine), or “reject” (reject and drop the email).
3. When a domain with a DMARC record fails either SPF or DKIM authentication, mailbox providers (Microsoft, Google, etc) will generate failure reports (RUA and RUF). These reports are sent to the defined email address and can be used to ascertain why “good” emails have failed and provide useful forensic intel on what unauthorised “bad” emails are being sent using your domain.

InfoTrust is supporting Australia’s Enterprise and Government organisations deploy DMARC for their Domain Authentication project. Please reach out if we can be of assistance to you.

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