Deniz A. - whose last name has not been released - told Bild newspaper in an interview on Wednesday that he and a friend hadn't set out to do anything wrong.
The 18-year-old says: "I'm sorry for everything I've done - I never thought it would go so far... we were only interested in the music."
Charges are yet to be filed.
Authorities say the two allegedly used a Trojan Horse malware to hack into the artists' computers for about 12 months before being discovered and earned more than euro10,000 ($13,240) in illegal sales.
The theft forced the advanced release of several singles, officials said Friday.
