Feeds

Turing test challenges spam filters

Fuzzy PDF menace

The Essential Guide to IT Transformation

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. ®

Build a business case: developing custom apps

More from The Register

next story
14 antivirus apps found to have security problems
Vendors just don't care, says researcher, after finding basic boo-boos in security software
'Things' on the Internet-of-things have 25 vulnerabilities apiece
Leaking sprinklers, overheated thermostats and picked locks all online
iWallet: No BONKING PLEASE, we're Apple
BLE-ding iPhones, not NFC bonkers, will drive trend - marketeers
Only '3% of web servers in top corps' fully fixed after Heartbleed snafu
Just slapping a patched OpenSSL on a machine ain't going to cut it, we're told
How long is too long to wait for a security fix?
Synology finally patches OpenSSL bugs in Trevor's NAS
Israel's Iron Dome missile tech stolen by Chinese hackers
Corporate raiders Comment Crew fingered for attacks
Tor attack nodes RIPPED MASKS off users for 6 MONTHS
Traffic confirmation attack bared users' privates - but to whom?
Roll out the welcome mat to hackers and crackers
Security chap pens guide to bug bounty programs that won't fail like Yahoo!'s
Researcher sat on critical IE bugs for THREE YEARS
VUPEN waited for Pwn2Own cash while IE's sandbox leaked
prev story

Whitepapers

Implementing global e-invoicing with guaranteed legal certainty
Explaining the role local tax compliance plays in successful supply chain management and e-business and how leading global brands are addressing this.
Boost IT visibility and business value
How building a great service catalog relieves pressure points and demonstrates the value of IT service management.
Why and how to choose the right cloud vendor
The benefits of cloud-based storage in your processes. Eliminate onsite, disk-based backup and archiving in favor of cloud-based data protection.
The Essential Guide to IT Transformation
ServiceNow discusses three IT transformations that can help CIO's automate IT services to transform IT and the enterprise.
Maximize storage efficiency across the enterprise
The HP StoreOnce backup solution offers highly flexible, centrally managed, and highly efficient data protection for any enterprise.