Fraudsters are launching phishing attacks that use custom 404 pages to steal users’ Microsoft login credentials.

As reported by Bleeping Computer, the Microsoft security researchers who analyzed the phishing attacks observed that digital fraudsters had registered a domain and configured a 404 error page to display a fake Microsoft login form designed to look exactly like Microsoft’s official login page. Threat actors lifted various links from Microsoft’s official page, including those used to create a new account and to sign in to an existing record, and included them in their fake portal.

By configuring a 404 error page instead of creating a single landing page, the phishers afforded themselves and their campaigns a significant degree of flexibility. Microsoft’s analysts noted that these fraudsters can essentially pair their domain with an infinite number of phishing landing pages. The researchers also observed attackers randomizing their domains, which further increased the number of phishing URL possibilities available to them going forward.

Phishers’ Ongoing Use of Fake 404 Pages

This isn’t the first time that phishers have used fake 404 pages to realize their malicious intentions. Back in 2016, for instance, Sucuri came across one campaign that redirected those coming from a security service to a 404 error page to protect their attacks. Two years later, Bleeping Computer discovered that attackers were using login pages disguised as HTTP error pages to access a web shell and issue commands on the server.

More recently, in February 2019, Sucuri spotted attackers using fake 404 error pages and reCAPTCHA elements as part of their efforts to distribute banking malware.

How to Defend Against Phishing Attacks

Security professionals can bolster their defenses against phishing attacks by investing in a security awareness program that teaches employees look out for suspicious links, malicious email attachments and other phishing-related techniques. Organizations should also adopt a layered approach to email security in which they verify that their perimeter protection systems have spam detection services.