MCBans.com:
It recently came to our attention that a list of approximately 1,000 Minecraft account names and passwords were made freely available on the internet. We believe this list consists of information collected by a group of malicious users from a well known "griefing team". How the information in this list was obtained is not sure, but we suspect they collected them through the use of hacked clients (that pretend to only give you extra features like flying or seeing through blocks but actually send your account information to the creators as well) or websites made to look like the official Minecraft site.
We urge you to change your passwords immediately at Minecraft.net. If you use the same password for anything Minecraft related i.e WoMRealms.com or on our forums please change them as-well to be on the safe side.
The official WoM Game Client is only distributed by us (WorldofMinecraft.com) and is available from the downloads section. Any other clients labeled "World of Minecraft Game Client" should not be trusted and are not legitimate.
On another note, please be careful when downloading plugins\addons for your server. You should only trust sites that are well known within the community.
Sources we trust:
WorldofMinecraft.com
MinecraftForum.net
Crafthub.net
MinecraftNews.net
McBans.com
If you have any concerns or problems, please feel free to reply with comment and I will try to help.