ninjhax is an exploit by smea for the game Cubic Ninja. It was released on November 20th, 2014. It can be used on all 3DS firmware versions from 4.0 up to and including 9.2.0-20. It was partially patched in 9.3.0-X (only system flaws used by ninjhax were fixed, the game haxx itself was not affected).
ninjhax 2 was released on 18 July 2015, and works on any system version from 9.0.0-X up to 11.3.0-X.
When triggered, it will boot a 3dsx-file from the sdcard root called "boot.3dsx". This file is usually the Homebrew Launcher, which in turn can be used to launch other games/apps from the (micro)SD card. The launched application will run with user privileges on the ARM11 CPU. On system versions up to 9.2.0-20, one of the publicly known 3DS System Flaws can be chained to gain ARM11 kernel privileges or to take control over the ARM9 CPU. More recent system versions are limited to ARM11 userland homebrew until new exploits are disclosed.
Visit (dead link!) for instructions on how to install Ninjhax, and here for instructions on how to install Ninjhax 2!
ninjhax gives developers access to a number of services. These include :
Additionally, Old 3DS models (3DS, 3DS XL and 2DS) are given access to the following :
In contrast, New 3DS models (New 3DS, New 3DS XL) get access to :
System Call Access
The following system calls are usable by homebrew running using ninjhax:
Allowed systemcalls: 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08 0x09, 0x0A, 0x0B, 0x0C, 0x0D, 0x0E, 0x0F, 0x10 0x11, 0x13, 0x14, 0x15, 0x16, 0x17, 0x18, 0x19 0x1A, 0x1B, 0x1C, 0x1D, 0x1E, 0x1F, 0x20, 0x21 0x22, 0x23, 0x24, 0x25, 0x27, 0x28, 0x29, 0x2A 0x2B, 0x2C, 0x2D, 0x2E, 0x2F, 0x30, 0x31, 0x32 0x35, 0x36, 0x37, 0x38, 0x39, 0x3A, 0x3B, 0x3C 0x3D
At the moment, ninjhax only allows users to access 64MB of RAM, including on the New 3DS. This may change in the future.
While sound works on the New 3DS for homebrew running via ninjhax 2.0, at the time of the exploit's original release, there was no good way to use the DSP from homebrew, so sound output is not possible on the New 3DS using the old version. At the moment, there is also no known way of running code on the New 3DS's extra CPU cores under ninjhax, though it is possible to use 80% of the system core's time using APT:SetApplicationCpuTimeLimit rather than 30% as was the case on the Old 3DS.