Sometimes the easiest solution is the best solution. And in the case of phishing attacks intent of stealing credentials using a fake logon page, it appears that background inversion does the trick.

Plenty of security solutions use crawlers to spot phishing sites before allowing users to navigate to them. And one of the more identifiable aspects of legitimate logon pages to sites such as Office 365 is the background. So, it makes sense that anytime a background image traditionally associated with a well-known authentication process shows up on some other website, it’s a sign there may be something suspicious afoot.

Well, it appears the bad guys have figured this out and have used the simplest of techniques to avoid detection: inversion. By simply inverting the picture background image (see below) using Cascading Style Sheets (CSS) when a crawler visits, the bad guys avoid detection.

Original next to inverted background

Source: PhishFeed

But what about when a human visits? It’s obvious something’s wrong. No problem. The CSS code automatically reverts the image to its normal presentation when an actual user visits, making them feel they’ve arrived at the appropriate page.

This one is so tricky, no user will ever know just by looking at the familiar background. But through new school Security Awareness Training, users can be taught to be mindful of the website URL, making certain it’s actually the legitimate vendor’s logon page and not a lookalike website.