DMARC Your Calendar: Google, Yahoo Send Spam Packing

October 22, 2015 @ 5:25 PM
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2 min read

Email spam is a problem. While overall numbers have been dropping, Securelist reported that in Q2 2015, more than 50 percent of all email traffic came from spammers. What’s more, malicious actors have changed tactics to focus on the next generation of tech-savvy consumers: Rather than looking for bank details or personal information, new phishing emails target social connections while malware-carrying attachments are camouflaged to look like antivirus or OS updates. But advancements in detection, particularly the DMARC protocol, have the potential to send spam packing.

Spam Has an Easy Way In

As noted by CSO Online, one of the easiest ways for attackers to convince victims their emails are genuine is by spoofing the sender address. If users believe the message really is from Microsoft, their antivirus company or a trusted friend, they’re far more likely to open, read and even download an attachment. And once attackers have access to a user’s system, they can both send emails from an infected account and use contact list data to spoof a whole new set of addresses.

While early spam-detection efforts focused on message content or relied on users to self-identify bad emails, attackers have quickly graduated to a new level of sophistication by lifting company logos, including working phone numbers and generally brushing up on their grammar. The result? Fake and legitimate messages look and sound almost identical.


Fortunately, Google and Yahoo have a plan: the Domain-based Message Authentication, Reporting and Conformance (DMARC) protocol. According to Threatpost, DMARC takes a hard line against email spoofing by checking all messages against both Domain Keys Identified Mail (DKIM) and Sender Policy Framework (SPF) validation systems.

DKIM relies on a wrapped cryptographic signature to verify the sender domain, while SPF lets senders specify which hosts are able to carry their messages, making spoofed emails easy to identify. In combination, the DMARC protocol makes it almost impossible for spam to slip through — if both the DKIM and SPF checks aren’t successful, the message is quarantined.

Under the new DMARC system, senders can provide information to recipients on what they can do if legitimate emails aren’t getting through, while recipients can send feedback to senders letting them know why their messages were flagged. Yahoo is set to implement the protocol for its and services by Nov. 2, 2015, while Google says it’s moving to a “strict” DMARC policy by June of next year.

While it’s unlikely that even DMARC can completely eliminate spam, it’s a step in the right direction; make spoofing messages hard enough for attackers and they’ll start looking somewhere else. Even with DMARC up and running, however, users can’t get overconfident: Better safe than spoofed.

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Douglas Bonderud
Freelance Writer

A freelance writer for three years, Doug Bonderud is a Western Canadian with expertise in the fields of technology and innovation. In addition to working for...
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