Cheating was when a player obtained extra items, earned extra coins, accessed unavailable or limited features, and so on, by way of third-party programs.
Cheating was strictly against the rules of Club Penguin, and any player that cheated got banned for 72 hours or forever, depending on previous offenses on the player's account. Using websites to find the location of a pin, a secret in a catalog, or a walkthrough for a game or party were not considered cheating. Club Penguin encouraged all secret agents, as well as every penguin, to report any suspected cheating.
Common cheating methods
Trainers were programs that were downloaded onto the player's computer. The player then plays Club Penguin through the program using addons and plugins to cheat Club Penguin. Many addons were client side, meaning that only the player using the program can see the hack. Players were unlikely to get banned for client-side hacks. Client-side hacks would include changing a penguin's name, color, size, or changing to mascot clothing.
Trainers were commonly used by players in the past, however, most have patched.
Follow bots, or "clones", were programs that caused "clones" of the player to follow them or (talk, throw snowballs at the same time etc.).
Adders were online or downloadable software that allowed the players who used it to get items on Club Penguin. These were the most common form of cheating, and players usually used these to gain extra items, coins, furniture, or igloos.
Known cheating/hacking incidents
- A hacking group known as "DERP" had taken down gaming sites such as EA.com, Battle.net and Club Penguin on/around December 30, 2013. 
- On April 28, 2014 the server Blizzard was hacked. Offensive postcards were sent to many players, and some innocent accounts were banned.
- In July 2014, players found an exploit which allowed people to add any item to their account. However, almost all have since been patched.
- On May 1, 2015, Club Penguin received a distributed denial of service attack from a user named "NULLROUT", resulting in many players not being able to login to the game for a few weeks.
- On June 28, 2016, a group of Clones took over Blizzard and many other servers for the next few weeks.