A teenager may be behind the massive security breaches at Target and Neiman Marcus.
The cyber watch group Intelcrawler said the source of the breaches can be traced to malicious software developed by a 17-year-old hacker in Russia.
Intelcrawler said the first sample of the software was created in March 2013. Stores in Australia, Canada and the U.S. have been affected.
Intelcrawler also believes at least six more retailers may have been attacked with the same malware.
Millions of people may have been affected by the credit card data breach at Target between Black Friday and Dec. 15. It's unknown how many people were affected by the breach at Neiman Marcus.
Information from CNN contributed to this report.