M3AAWG Recommends Adding New Email Header to Mitigate List Bomb Attacks from Subscription Sign-Up Forms

SAN FRANCISCO, Nov. 29, 2017 (GLOBE NEWSWIRE) -- Noticing an increase in "list bomb" activity, the Messaging, Malware and Mobile Anti-Abuse Working Group is recommending all blogs and websites with a newsletter or sign-up form add a new header to their verification emails that will help identify and disrupt these attacks. The assault tactic is often used to hide security alerts of illicit activities or to prevent someone, such as a journalist, from receiving vital information.

In the assaults, also called a web-form sign-up attack, criminals use bots to subscribe their targeted victims to thousands of newsletters or other services that automatically send verification emails.  The resulting surge of confirmation emails, in effect, creates a DDoS (Distributed Denial of Service) attack against the users' inboxes. Very often, buried within the unmanageable mountain of verification messages is a notice from a credit card company or other financial institution outlining a forged transaction or an account password reset alert that the victim will never see.

"A few years ago, a torrent of useless verification messages bombarding a user's inbox was an isolated event and was probably the result of a grudge against someone. But today criminals have started using these attacks to subvert the security notifications that many banks, services and e-tailers are now sending.  Their aim is to submerge the specific alert email with details of their fraudulent activities under a sea of meaningless messages or to deny a journalist or activist access to their email altogether," said Severin Walker, M³AAWG Chairman of the Board.

Industry Collaboration Leads to IETF Internet Draft Header Specification

The new message header specification has been submitted to the IETF (Internet Engineering Task Force) at https://datatracker.ietf.org/doc/draft-levine-mailbomb-header/ and is explained in a short paper, M³AAWG Recommendation on Web Form Signup Attacks (www.m3aawg.org/WebFormAttacks), available in the Best Practices section of the M3AAWG website. The new header specifically identifies messages that originate as verification emails from a web-form, such as a subscription confirmation email, so that ISPs and email providers can take action to protect a user's inbox when an extraordinarily high volume of these messages come across their networks.

M³AAWG also recommends that all public subscription and web forms install one of the various types of CAPTCHA image or text challenges used to tell humans from automated sign-ups that are readily available.  This will help protect against bots misusing the site's verification emails in an attack.  

The header concept came out of discussions at the M³AAWG meeting in June among members who noted a significant increase in these attacks.  An ad hoc technical session at the meeting with members from different segments of the messaging industry resulted in M³AAWG Senior Technical Advisor John Levine drafting the specification.  At the following meeting in October, the first members to implement the new specification shared their experiences and reported the process was sustainable.

Levine said, "Criminals routinely use bots to crawl the global web looking for the millions of blogs and newsletter sign-up forms that don't have CAPTCHA then use these sites, with their weaker security, to sign-up victims as part of an attack.  The new header is another level of protection that can have a significant impact on preventing list bombing and we are encouraging email service providers to implement it as soon as possible."

Web form attacks will continue to be monitored at the next M³AAWG meeting to be held February 19-22, 2018 in San Francisco.  The multiple-track event is expected to attract more than 500 participants with sessions addressing diverse topics such as bot mitigation practices, social networking abuse, mobile abuse and pending legislation worldwide.

About the Messaging, Malware and Mobile Anti-Abuse Working Group (M ³ AAWG)

The Messaging, Malware and Mobile Anti-Abuse Working Group (M³AAWG) is where the industry comes together to work against bots, malware, spam, viruses, denial-of-service attacks and other online exploitation. M³AAWG (www.m3aawg.org) members represent more than one billion mailboxes from some of the largest network operators worldwide. It leverages the depth and experience of its global membership to tackle abuse on existing networks and new emerging services through technology, collaboration and public policy. It also works to educate global policy makers on the technical and operational issues related to online abuse and messaging. Headquartered in San Francisco, Calif., M³AAWG is driven by market needs and supported by major network operators and messaging providers.

Media Contact: Linda Marcus, APR, +1-714-974-6356 (U.S. Pacific), LMarcus@astra.cc, Astra Communications

M³AAWG Board of Directors: AT&T; Cloudmark, Inc.; Comcast; dotmailer; Endurance International Group; Facebook; Google; LinkedIn; Mailchimp; Microsoft Corp.; Oath (Yahoo and AOL); Orange; Rackspace; Return Path; SendGrid, Inc.; Vade Secure.

M³AAWG Full Members: 1&1 Internet AG; Adobe Systems Inc.; Agora, Inc.; AOL; Campaign Monitor Pty.; Cisco Systems, Inc.; CloudFlare; Exact Target, Inc.; IBM; iContact; Inteliquent; Internet Initiative Japan (IIJ); Liberty Global; Listrak; Litmus; McAfee; Mimecast; Nominum, Inc.; Oracle Marketing Cloud; OVH; PayPal; Proofpoint; Spamhaus; Sparkpost; Splio; Sprint; Symantec; and USAA.

A complete member list is available at http://www.m3aawg.org/about/roster.