Here's the background. My youngest has had Minecraft for quite some time. Lately, he's been wanting to download "mod packs". If I understand this correctly, these are user generated data packs that add to the base Minecraft game. From a security standpoint (he uses the primary household computer), I'm not crazy about downloading user generated code onto my computer. Curious if any of the computer gurus on here have any info/feedback on this topic.
So the answer is that yes, adding mods is going to increase the security risk, but the amount by which it does it will vary a lot. It depends partly on how the mods are implemented -- for example, mods that simply add variety within the existing game rules (new levels, new skins, new weapons, things like that) are often just data files that are plugged into the game engine. The things you can do to the computer using these kinds of files are fairly limited, at least until someone finds bugs in the game engine that can be exploited this way. Some games (not sure if Minecraft is one or not) are implemented using an in-game language interpreter, which is more powerful (and thus riskier) than simple data files, but not as powerful (nor as risky) as installing native Windows DLLs.
Another risk factor is the source of the mods. Most games with large mod communities have one or more central repositories for those mods. A mod that is popular and retrieved from one of these repositories is less likely to represent a security risk than one that comes from a shadier source.
Nothing is 100% secure, if your machine is on the internet it can be attacked. That said, game mods do not seem to be a particularly common vector for such attacks at this point.
My son who is all things Minecraft and for that very reason we built him his own computer has had no issues with mods for Minecraft. In fact his computer has been trouble free since we built it more than a year ago.
I asked him about this and he recommended the "Technic Launcher" as the best way to mod Minecraft.
Another parent who's had no problems with the Minecraft add ons.
Get him a Raspberry Pi. You can play minecraft on it, its $35, and it if he grenades it, just pull the SD card out and reformat it.
Thanks, as always, you guys are awesome.