Zero-day vulnerability found in a Wordpress image utility

The problem lies in TimThumb, a utility that can allow a malicious PHP file to be written to a Wordpress directory

Hackers are exploiting a problem with an image-resizing utility called TimThumb that is widely used in many themes for the blogging platform WordPress, although some fixes have been made to the latest version.

Mark Maunder, the CEO of Feedjit, discovered the problem when his own blog started loading ad content when previously his blog contained no ads. He blogged about the problem, tracing it to an issue with the "timthumb.php" library, which is used within the theme he purchased for his blog.

"Since it's already in the wild and I just got hacked by it, I figure it's OK to release the vulnerability to the general public," Maunder wrote.

TimThumb is "inherently insecure" because it writes files into a directory when it fetches an image and resizes it. But that directory is accessible to people visiting the website, Maunder wrote. An attacker can compromise the site by figuring out how to get TimThumb to grab a malicious PHP file and put it in the Wordpress directory. The code will be executed if an attacker then accesses the file using a Web browser.

Maunder explained how to disable TimThumb's ability to load images from external sites, but the most sure-fire way to stop the problem is to remove TimThumb or limit its access to other websites. Aside from that, users should update to the latest version of TimThumb.

The developer of TimThumb, Ben Gillbanks, was the first to comment on Maunder's post. "I can't apologize enough for this oversight in the code and hope nobody has anything too bad happen to their sites because of my error."

Gillbanks recommended that people use the latest version of TimThumb. "There have been a stack of tweaks that will make the script harder to abuse," Gillbanks wrote.

Join the newsletter!

Or

Sign up to gain exclusive access to email subscriptions, event invitations, competitions, giveaways, and much more.

Membership is free, and your security and privacy remain protected. View our privacy policy before signing up.

Error: Please check your email address.

Tags data protectionWordpressExploits / vulnerabilities

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

Jeremy Kirk

IDG News Service
Show Comments

Cool Tech

Toys for Boys

Family Friendly

Stocking Stuffer

SmartLens - Clip on Phone Camera Lens Set of 3

Learn more >

Christmas Gift Guide

Click for more ›

Brand Post

Most Popular Reviews

Latest Articles

Resources

PCW Evaluation Team

Aysha Strobbe

Microsoft Office 365/HP Spectre x360

Microsoft Office continues to make a student’s life that little bit easier by offering reliable, easy to use, time-saving functionality, while continuing to develop new features that further enhance what is already a formidable collection of applications

Michael Hargreaves

Microsoft Office 365/Dell XPS 15 2-in-1

I’d recommend a Dell XPS 15 2-in-1 and the new Windows 10 to anyone who needs to get serious work done (before you kick back on your couch with your favourite Netflix show.)

Maryellen Rose George

Brother PT-P750W

It’s useful for office tasks as well as pragmatic labelling of equipment and storage – just don’t get too excited and label everything in sight!

Cathy Giles

Brother MFC-L8900CDW

The Brother MFC-L8900CDW is an absolute stand out. I struggle to fault it.

Luke Hill

MSI GT75 TITAN

I need power and lots of it. As a Front End Web developer anything less just won’t cut it which is why the MSI GT75 is an outstanding laptop for me. It’s a sleek and futuristic looking, high quality, beast that has a touch of sci-fi flare about it.

Emily Tyson

MSI GE63 Raider

If you’re looking to invest in your next work horse laptop for work or home use, you can’t go wrong with the MSI GE63.

Featured Content

Don’t have an account? Sign up here

Don't have an account? Sign up now

Forgot password?