Twitter now blocking bad URLs, but imperfectly

The service doesn't filter URLs that have been shortened using Tinyurl or

Hoping to deal with a growing problem, Twitter has quietly introduced a feature to prevent users from posting links to malicious Web sites. But security experts say that it can be easily circumvented.

The feature was first noticedMonday by Mikko Hypponen, chief research officer with security company F-Secure.

When someone tries to post a link to a malicious Web site, Twitter pops up a short notification saying "Oops! Your tweet contained a URL to a known malware site," and, after a few seconds, deletes the post.

Twitter is using Google's Safe Browsing API to check for malicious links, a Google spokesman confirmed Monday.

F-Secure says it's recommended that Twitter start doing this because the site "is increasingly targeted by worms, spam and account hijacking," according to Hypponen's blog post.

A month ago, technology entrepreneur Guy Kawasaki's account was misused to post a link to a malicious Web site. In recent weeks users have been hit with links to fake, and sometimes malicious, "rogue" security software.

Security experts said Monday that while Twitter's filtering is a good first step, it still needs some work.

In tests, the feature blocked a URL that led to a phishing site, but it allowed the same link to post if it was shortened using services such as or

Because Twitter enforces a strict 140 character limit on each message, these URL shortening services are the most common way of posting links to Twitter.

The filter also permitted the phishing link when the "www" subdomain was stripped from the front of the URL.

Twitter did not return messages seeking comment.

It is not clear whether Twitter is filtering the malicious domains itself or using some other services such as Google's Safe Browsing API.

"This is a common problem with this sort of filtering service," said Chris Boyd, director of malware research with FaceTime Security Labs.

However, even if Twitter isn't blocking malicious URLS when they've been shortened, users still get some protection. That's because some of these URL-shorteners use the Google's API themselves., which is used to post more than half of all Twitter links uses the API to block people from visiting malicious sites, for example.

Boyd said it will probably take Twitter "a while" to get its Web filtering up and running properly, "but even some protection is better than none."

Join the Good Gear Guide newsletter!

Error: Please check your email address.

Tags securityURLstwitteranti-malwaresocial networks

Our Back to Business guide highlights the best products for you to boost your productivity at home, on the road, at the office, or in the classroom.

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

Robert McMillan

IDG News Service
Show Comments

Cool Tech

D-Link PowerLine AV2 2000 Gigabit Network Kit

Learn more >

Xiro Drone Xplorer V -3 Axis Gimbal & 1080p Full HD 14MP Camera

Learn more >

D-Link TAIPAN AC3200 Ultra Wi-Fi Modem Router (DSL-4320L)

Learn more >

Lexar® Professional 1000x microSDHC™/microSDXC™ UHS-II cards

Learn more >

ASUS ROG Swift PG279Q – Reign beyond virtual world

Learn more >

Crucial® BX200 SATA 2.5” 7mm (with 9.5mm adapter) Internal Solid State Drive

Learn more >

Gadgets & Things

Lexar Professional 2000x SDHC™/SDXC™ UHS-II cards

Learn more >

Lexar® Professional 1000x microSDHC™/microSDXC™ UHS-II cards

Learn more >


Learn more >

Family Friendly

Lexar® Professional 1000x microSDHC™/microSDXC™ UHS-II cards

Learn more >

Lexar Professional 2000x SDHC™/SDXC™ UHS-II cards

Learn more >

ASUS VivoPC VM62 - Incredibly Powerful, Unbelievably Small

Learn more >

Stocking Stuffer

Lexar Professional 2000x SDHC™/SDXC™ UHS-II cards

Learn more >

Lexar® Professional 1000x microSDHC™/microSDXC™ UHS-II cards

Learn more >

Christmas Gift Guide

Click for more ›

Most Popular Reviews

Best Deals on Good Gear Guide

Latest News Articles


GGG Evaluation Team

Kathy Cassidy


First impression on unpacking the Q702 test unit was the solid feel and clean, minimalist styling.

Anthony Grifoni


For work use, Microsoft Word and Excel programs pre-installed on the device are adequate for preparing short documents.

Steph Mundell


The Fujitsu LifeBook UH574 allowed for great mobility without being obnoxiously heavy or clunky. Its twelve hours of battery life did not disappoint.

Andrew Mitsi


The screen was particularly good. It is bright and visible from most angles, however heat is an issue, particularly around the Windows button on the front, and on the back where the battery housing is located.

Simon Harriott


My first impression after unboxing the Q702 is that it is a nice looking unit. Styling is somewhat minimalist but very effective. The tablet part, once detached, has a nice weight, and no buttons or switches are located in awkward or intrusive positions.


Latest Jobs

Don’t have an account? Sign up here

Don't have an account? Sign up now

Forgot password?