Fifteen people were arrested in China last week for allegedly creating and selling hacks for online battle royale game “PlayerUnknown’s Battlegrounds,” developer PUBG Corp. said in a Steam update Friday.

Some of the cheating programs include a Chinese backdoor virus called a Huigezi Trojan horse, local authorities working with PUBG Corp. on the case said. Hackers can apparently control a person’s PC with this virus, scan their data, and extract information illegally. “The longstanding rumor that hacking/cheating programs extract information from users’ PCs has been confirmed to be true,” they said. “Using illegal programs not only disrupts others, but can end up with you handing over your personal information.”

Hacking is a big issue for “PUBG.” Anti-cheat company BattlEye has banned over 1.5 million accounts so far, it tweeted last December. It banned over a million more in January alone. “Unfortunately, things continue to escalate,” it said.

PUBG Corp. said it takes cheating in its game “extremely seriously.” “Developing, selling, promoting, or using unauthorized hacking/cheating programs isn’t just unfair for others playing ‘PUBG’ — in many places, it’s also against the law,” it said. “We’ve upgraded our security measures, improved our anti-cheat solutions, and recently even added a new anti-cheat solution on top of all that. In the meantime, we’ve also been continuously gathering information on hack developers (and sellers) and have been working extensively with multiple partners and judicial authorities to bring these people to justice.”

The 15 people arrested were fined approximately 30 million RNB ($5.1 million USD). Police are still investigating other suspects.