OP-Sign
Type	Hack
Category	Blocks
In-game description	“Enable this mod, place a sign and click it to get OP. Can also be used to run any other command. Only works on servers running Minecraft 1.8 - 1.8.5 without Spigot! Type .sv to check the server version.”
Default keybind	none

OP-Sign allows the user to execute commands like /op by simply placing a sign and then right-clicking on it. A server running Minecraft 1.8 - 1.8.5 without Spigot is required in order for OP-Sign to work.

OP-Sign was originally created by Alexander01998 on June 12, 2015¹⁾, three weeks after the OP-Sign exploit had already been patched through Minecraft 1.8.6²⁾³⁾. The initial version, released in Wurst 1.15, only worked in Creative Mode. Survival Mode support for the feature was added by Alexander01998 on September 19, 2015⁴⁾ and then released in Wurst 2.5.

The exploit behind OP-Sign was originally discovered by CrushedPixel on May 20, 2015⁵⁾⁶⁾⁷⁾, who also created the first mod to ever take advantage of the exploit⁸⁾. CrushedPixel quickly reported the exploit to Mojang in MC-75630⁹⁾ and Mojang patched the OP-Sign exploit on May 22, 2015¹⁰⁾, by releasing Java Edition 1.8.6. This all took place long before the OP-Sign hack was added to Wurst.

The easiest way to find servers that have the right Minecraft version is to use ServerFinder. After using ServerFinder, you should have a huge list of servers with green text showing their versions. Now simply look for one that has the correct version and join it. Now you need to get a sign, but don't place it yet.

You first need to turn on the OP-Sign hack. A new screen will show up that asks you to enter a command. By default, the command is set to /op YourName, which will give you operator permissions on most servers. After that, just click the “Done” button.

Finally, you need to place the sign and right click on it. You should now be an OP on that server. Contrary to popular belief, you do not need to click the sign multiple times. It's actually better to click it only once because that creates only one message in the server logs, making it less noticeable for the server owner.

If doing this did not OP you on that server, it's either a server with the wrong version (again: only Minecraft 1.8 - 1.8.5 will work), a server with Spigot installed or one of those strange servers that won't work despite meeting the requirements. Should this happen to you, please do not freak out and just try a different server.