Almost 6,000 web shops are unknowingly harbouring malicious code that is stealing the credit card details of customers,suggests research.
The code has been injected into the sites by cyberthieves, said Dutch developer Willem De Groot.
He found the 5,925 compromised sites by scanning for the specific signature of the data-stealing code in website software.
Some of the stolen data was sent to servers based in Russia, he said.
Costly mistake
In a blogpost, Mr De Groot said the attacks exploited known vulnerabilities in several different widely used web retailing programs. Mr De Groot is co-founder and head of security at Dutch ecommerce site byte.nl