The history of gaming is a long and complicated one, but the last few decades have seen a transformation happening because of the video game industry—specifically, as a result of personal computers, video game consoles that have become more affordable over time, and due to the growth of video games with a whole range of player modes and storylines. Since they’ve spread into the average home, becoming more than just a past time for nerds to play in their basements, they’ve also been the subject of much enquiry, hand wringing, and frustration from concerned academics, parents, and politicians who wonder whether they are ‘corrupting’ young minds. Last week, a number of investigations found that there may have been some merit to those worries, just not in the way you might think.

Loot boxes and purchases within video games have become contentious for as long as they’ve been around—some argue that they waste people’s money, others argue that they’re a negative influence on young minds developing impressions about the world around them. One step further are the criminals and masterminds who are using virtual money to launder real money, which almost sounds like the plot of a particularly uninspiring video game.

The Counter-Strike: Global Offensive game, which was initially launched in 2012, had more than 18 million unique users per month. Run by the gaming company Valve, Counter-Strike: Global Offensive pits players against each other in two teams. The basic structure is that they have to protect certain objects, try and garner loot and winnings, while eliminating the other team at the same time. During this time, gamers could earn loot boxes, but in order to open them, they had to buy a key from Valve. But this was only possible through their internal Steam marketplace, using real money. Boxes and keys were tradeable on the Steam marketplace.

A Vice investigation found that the majority of transactions that were taking place in this way were actually part of a worldwide, completely real fraud network. As a result, nearly all of these transactions were identified as fraud-sourced, where criminals were using them as a money-laundering marketplace. Counter-Strike: Global Offensive was previously in the news for financial related misdeeds, when two very popular streamers encouraged their fans to bet on certain cosmetic upgrades and attributes in the game, without divulging that they would benefit financially as a result.

In order to launder money through a video game, a few different things have to happen. Cybercriminals hack into accounts, often unprotected or without two factor authentication, and are able to use strings of numbers of stolen credit cards to purchase in-app money. These items and currency can then be re-sold in an online grey market for a fraction of the price, but because it’s difficult to identify fraud before it happens or proactively stop these mechanisms, game publishers and those in the games companies themselves only become aware of these transactions after the fact, usually months later. At this point, it’s often impossible to catch the initial fraudster, who may be able to re-start this process (or already has).

Since then, Valve said it will be shutting down its online marketplace in order to stop such fraudulent practices from proliferating further, although it has also admitted that legitimate transactions may get caught up in this loop.

But loot boxes and gambling in video games have continued to be a source of suspicion. In January of this year, an article in Slate found that cybercriminals were using the in-game currency to launder money. This article found that such criminals were using stolen cards to buy V-bucks, the Fortnite currency, en masse, before they sold them in bulk amounts, and for cheaper, on the internet. These kinds of scams were happening around the globe, potentially made easier by the rise of platforms like Twitch, which enables video game players around the world to stream and play video games together, and also makes it easier for people to find new audiences around the world.

While Valve dealt with the problem quickly, and efficiently by shutting down the entire marketplace altogether, this might not have been so easy for smaller game developers, and it’s likely that they’ll see the ramifications in terms of user satisfaction. So, whether you are a gamer or not, watch out for your credit cards.