(CNN) – A security firm believes a Russian teenager is responsible for the malware used in a cyberattack on Target.
The breach compromised the credit card numbers and the personal information of millions of Target customers.
In a statement published Friday, security firm Intercrawler said the malware was written by a 17-year-old with roots in St. Petersburg.
Experts said the first sample of the code was finished last March. Since then, more than 40 versions of the malware have been sold around the world, they said.
Cybersecurity experts warn the malware may have already infected other retailers and more breaches may happen as a result.