Abandoned subdomains pose security risk for businesses

Attackers could hijack subdomains pointed by companies at external services they no longer use, researchers say

Many companies set up subdomains for use with external services, but then forget to disable them when they stop using those services, creating a loophole for attackers to exploit.

Because many service providers don't properly validate the ownership of subdomains pointed at their servers, attackers can set up new accounts and abuse subdomains forgotten by companies by claiming them as their own.

Removing or updating DNS entries for subdomains that are no longer actively used sounds like something that should be common procedure, but according to researchers from Detectify, a Stockholm-based provider of website security scanning services, this type of oversight is actually quite widespread among companies.

"We've identified at least 17 Service Providers which do not handle the subdomain ownership verification properly -- allowing this vulnerability to be exploited, Heroku, Github, Bitbucket, Squarespace, Shopify, Desk, Teamwork, Unbounce, Helpjuice, HelpScout, Pingdom, Tictail, Campaign Monitor, CargoCollective, StatusPage.io and Tumblr," the Detectify researchers said in a blog post earlier this week.

"We've also identified at least 200 organizations which are currently affected," the researchers said. "In many cases, we are talking NASDAQ-listed, top 100 Alexa rank domains that basically allowed us to set up a Hello World on their domains."

The risk to website owners depends on what can be done on a third-party service once a domain is pointed to it. If the service allows users to set up Web pages or Web redirects, attackers could exploit the situation to launch credible phishing attacks by creating rogue copies of the main website.

In an attack scenario described by Detectify, a company might set up a subdomain for use with an external support ticketing service, but later close its account and forget to delete the subdomain. Attackers could then create a new account with the same service and claim the company's subdomain, which already has the needed DNS settings, as their own, allowing them to set up a fake website on it.

Some of the subdomains exposed to this form of hijacking that were found by Detectify belonged to various types of organizations including government agencies, health services providers, insurance companies and banks.

The security firm created an online tool that can help organizations check if they have subdomains vulnerable to this attack. The tool requires users to first prove they have control over the domains they intend to scan by using several methods.

Some service providers use similar checks. For example, to use Google Apps with a custom domain name the domain administrator needs to upload a specific HTML file to the Web server hosting the domain, to add a TXT or CNAME record in their domain's DNS settings or to add a specific meta tag to their website's home page. All these methods are forms of domain ownership verification.

Join the newsletter!

Error: Please check your email address.
Rocket to Success - Your 10 Tips for Smarter ERP System Selection

Tags GitHubonline safetysecurityAccess control and authenticationherokuExploits / vulnerabilitiesDetectify

Keep up with the latest tech news, reviews and previews by subscribing to the Good Gear Guide newsletter.

Lucian Constantin

IDG News Service
Show Comments

Most Popular Reviews

Latest Articles

Resources

PCW Evaluation Team

Sarah Ieroianni

Brother QL-820NWB Professional Label Printer

The print quality also does not disappoint, it’s clear, bold, doesn’t smudge and the text is perfectly sized.

Ratchada Dunn

Sharp PN-40TC1 Huddle Board

The Huddle Board’s built in program; Sharp Touch Viewing software allows us to easily manipulate and edit our documents (jpegs and PDFs) all at the same time on the dashboard.

George Khoury

Sharp PN-40TC1 Huddle Board

The biggest perks for me would be that it comes with easy to use and comprehensive programs that make the collaboration process a whole lot more intuitive and organic

David Coyle

Brother PocketJet PJ-773 A4 Portable Thermal Printer

I rate the printer as a 5 out of 5 stars as it has been able to fit seamlessly into my busy and mobile lifestyle.

Kurt Hegetschweiler

Brother PocketJet PJ-773 A4 Portable Thermal Printer

It’s perfect for mobile workers. Just take it out — it’s small enough to sit anywhere — turn it on, load a sheet of paper, and start printing.

Matthew Stivala

HP OfficeJet 250 Mobile Printer

The HP OfficeJet 250 Mobile Printer is a great device that fits perfectly into my fast paced and mobile lifestyle. My first impression of the printer itself was how incredibly compact and sleek the device was.

Featured Content

Latest Jobs

Don’t have an account? Sign up here

Don't have an account? Sign up now

Forgot password?