Wii U system flaws

PPC userspace exploits

RenderArena use-after-free

Present in system versions: 2.0.0-5.1.0

Public in libwiiu: Yes

An iframe is removed from its parent in a beforeload event and freed, but accessed for a vtable call later. Using Javascript, a vtable pointer is sprayed, occupying the frame's previous memory. A forged vtable referred to by the pointer is also sprayed. When WebKit attempts the virtual call, it goes to the forged vtable, which starts a ROP chain. More information here.

JSStringJoiner heap overflow

Application: Internet Browser

Present in system versions: 5.1.1-5.3.1 (possibly older versions, too)

Publicly exploited in: : libwiiu (5.3.2 only)

When joining an array of strings, the lengths of the strings are summed to calculate the needed storage space. This summation is vulnerable to an integer overflow, which enables a heap overflow. As a result, a sprayed value from Javascript ends up as a vtable pointer, which can be used with a forged vtable to start a ROP chain. More information here.

PPC kernel exploits

OSDriver race attack

Present in system versions: 2.0.0-5.4.0

Publicly exploited in: : libwiiu

The Cafe OS kernel implements a structure called an OSDriver, which can hold a 0x1000-byte cross-process data area. Accessing this data area is done through the CopyToSaveArea() and CopyFromSaveArea() syscalls. However, no lock on the OSDriver is held during the copy, allowing the save area to be freed and reallocated while the copy is taking place. With all 3 PPC cores, it is possible to copy over an OSDriver structure, and create a save area that points at the syscall table, giving PPC user mode code access to it. More information here.

IOSU module exploits

ioctlvhax - ioctlv TOCTOU

Present in system versions: ???-5.2.0

This flaw technically is in the kernel, but it can be used to exploit a usermode module. It allows changing an ioctlv vector buffer address entry after it has been validated by the kernel. Any module not checking the number of ioctlv vectors is vulnerable. More information here.

IOSU kernel exploits

IOS_CreateThread unchecked memset

Present in system versions: ???-latest

This system call will fill the stack of the newly created thread with a predefined constant (0xFA5A5A5A) without validating the passed stack address.