In the game World of Warcraft, you can play with the default interface. Over the past few years this has become much easier to work with than when the game originally came out. At times the default interface does not do as much which is where player created mods can be used to give the layout a bit more functionality. While most of these mods are safe to use, there are security and privacy issues that you should be aware of when using these mods.
Always download your mods from a trusted source. There are some who made these types of files that are malicious in nature. This means they are designed to ultimately steal your account’s login name and password. If you hear about a mod that makes the game better, do some research to make sure that it is really secure. If you download only from the trusted websites, this should not be a problem. Always read user comments on the mod to make sure there isn’t an issue with it that you need to be aware of.
Some mods take some of your information and share it with the world. For example, there are mods that take the race and class of your character on your server to show this data to others from server to server. This is harmless information to be shared. Some mods though show others when you are online remotely and show what your usual playtime habits are.
While these are not designed to be malicious, someone could use this data to know when you are home and what you are doing. When you install anything of this nature, be sure to read the fine print and get an understanding of what data is going to be shared by using this addon.
There really is not a reason to be completely afraid of these mods. You just need to be aware of some of the issues that are brought up about them.