Note: you will remain your current level and your commendations will stay where they are Also this wasnt found by me This was found by MBP on xbox chaos.

Requirements
You need a Package Manager of the Horizon/Modio variety.
You need exProfileEditor.
It also requires something like XB36Hazard's Halo 4 Profile Editor to fix the security on the gpd. Or you could fix it manually if you know how.
(If you have a modded xbox, you can skip all of this and go to the bottom section of the tutorial)

Tutorial

Profile Extraction

First, back up your profile.
If this does not seem to work, try recovering your profile before modding it. Test offline first, so that if you mess up it does not upload the incorrect data.


Open your profile in the Package Manager of your choosing.

Extract the following files (or every file, if you so wish) from your profile to a folder of your choice:

Account
4D530919.gpd
FFFE07D1.gpd
tile_32.png
tile_64.png

Extracting the settings files

In exProfileEditor, click 'Open Profile' and direct it to the folder you extracted those files to.

Click on 'Halo 4" under 'Games' on the right hand side. On the left side, click 'Entries' and then 'Setting' below it. Extract the 'TitleSpecific1' and 'TitleSpecific2' files.
[spoiler]
In case you aren't familiar with this program:
[/spoiler]

Editing the settings files.

Open up TitleSpecific1 in a Hex Editor of your choosing.

Go to the very end, and select the last 0x120 (288 decimal) bytes in the file. Overwrite it (in Hex Workshop, I have to do 'paste special' and check 'interpret as a hexidecimal string') with the following bytes:


Save the file.

That table briefly continues on to the next setting file.

Open up TitleSpecific2 and select the very first 4 bytes in the file. Overwrite it with:

[spoiler][/spoiler]

Save the file.

Saving the GPD

In exProfileEditor, click on TitleSpecific1, and at the bottom of the window you should see 'Inject'. Click 'Inject', and select the TitleSpecific1 file you just modified.

Repeat for TitleSpecific2.

Save the GPD (Select 'Save to local files'). The profile page will re-open, but you may close exProfileEditor at this point regardless.

Resigning the GPD

If you are using XB36Hazard's Halo 4 Profile Editor to resign, open the GPD in the tool, and immediately hit 'Save' to fix the security.

(Comment if you have another tool you could use to do this, I use a modified HaloSigner so it's not exactly my code to be posting).

Injecting the GPD

Back in your Package Manager, inject/replace the now modded 4D530919.gpd into the profile. Rehash and Resign, then put the profile back on your device (if it was not being edited from there, of course), and you're done.


Jtag/Rgh/Dev Method

While on the main menu of Halo 4, signed into your profile, open Ascension's "Advanced Poker".

Set the Offset 0xC274FD18, set the value type to Bytes, set the size to 292 and paste the following:

Poke.
[spoiler][/spoiler]

Change some armor colors or something (to make the gpd data actually save), then restart the game to check if it saved properly.

**Sorry if the memory offset isn't static, I assumed it was because multiple xbox's and profiles have had it in the same location.**

Disclaimer:

This does work online. There is no automatic detection/ban at this point in time, but I cannot predict what they may or may not detect/ban for in the future.

Use online at your own risk.