Recently arrested in his home city, the youngster would allegedly download these apps from third-party download sites, modify them to include the Trojan, then reintroduced these trojanized versions onto the sites.
Once downloaded and run, the Trojan would secretly send 30 messages to a premium-rate number in exchange for receiving an SMS code for playing online lotteries. The Trojan would divert the message to the young man, who would then use the codes for playing.
The amount of money stolen from each of the 17,000 users who unknowingly downloaded the malware might not be huge, but the hacker's earnings would have been if he had managed to actually get his hand on the money. According to the Europa1 report (via Google Translate), he never won in those lotteries.
The man admitted to the crimes when he was arrested by the agents of the Central Office for the Fight against Crime Linked to Information Technology and Communication (OCLCTIC), saying that he was not motivated by the earnings, but by his love of computers.
According to the report, he has apparently never studied computer science, but wants to become a software developer.
He is not the first French national to be arrested for spreading SMS Trojans - in February, two men were arrested in Bobigny, a small town in the northeastern suburbs of Paris, for creating and spreading the Foncy Trojan.
Reading our newsletter every Monday will keep you up-to-date with security news.
Receive a daily digest of the latest security news.