Feeds

Turing test challenges spam filters

Fuzzy PDF menace

Securing Web Applications Made Simple and Scalable

Spammers have turned a widely-used anti-spam trick - fuzzy text that computers cannot recognise - to their own advantage, according to the head of an anti-spam software developer.

The distorted text images are arriving in PDF files touting German penny stocks, in yet another iteration of the pump-and-dump scam that's been around for a while now.

What's different from earlier image spam is not only that these are PDFs, which adds an extra layer of complexity to the task of filtering out spam, but the text inside is deliberately distorted to make it extra-hard for computers to recognise.

Neil Cook, European technology chief at anti-spam specialist Cloudmark, called it "a kind of Turing test for spam filters".

He added: "We've been seeing a lot of PDF stock spams for the last 10 days or so, and there was another spike last night. Images are particularly easy for humans to pick up, but particularly hard for computers.

"These ones are distorted too - it's the same technique that websites use to keep spammers off by making visitors type in distorted text during registration, and now the spammers are using it on us."

Cook claimed that Cloudmark's spam fingerprinting technology is holding off the unwanted PDFs for now, but said that new detection techniques could be needed if image spam continues to grow. ®

Mobile application security vulnerability report

More from The Register

next story
LibreSSL RNG bug fix: What's all the forking fuss about, ask devs
Blow to bit-spitter 'tis but a flesh wound, claim team
Manic malware Mayhem spreads through Linux, FreeBSD web servers
And how Google could cripple infection rate in a second
NUDE SNAPS AGENCY: NSA bods love 'showing off your saucy selfies'
Swapping other people's sexts is a fringe benefit, says Snowden
Own a Cisco modem or wireless gateway? It might be owned by someone else, too
Remote code exec in HTTP server hands kit to bad guys
British data cops: We need greater powers and more money
You want data butt kicking, we need bigger boots - ICO
Crooks fling banking Trojan at Japanese smut site fans
Wait - they're doing online banking with an unpatched Windows PC?
NIST told to grow a pair and kick NSA to the curb
Lrn2crypto, oversight panel tells US govt's algorithm bods
prev story

Whitepapers

Reducing security risks from open source software
Follow a few strategies and your organization can gain the full benefits of open source and the cloud without compromising the security of your applications.
Consolidation: The Foundation for IT Business Transformation
In this whitepaper learn how effective consolidation of IT and business resources can enable multiple, meaningful business benefits.
Application security programs and practises
Follow a few strategies and your organization can gain the full benefits of open source and the cloud without compromising the security of your applications.
Boost IT visibility and business value
How building a great service catalog relieves pressure points and demonstrates the value of IT service management.
Consolidation: the foundation for IT and business transformation
In this whitepaper learn how effective consolidation of IT and business resources can enable multiple, meaningful business benefits.