Difference between revisions of "Exploits"

Latest revision as of 23:40, 9 January 2024

MCPX

LDT (Hypertransport) bus tap

See bunnie's adventures hacking the Xbox.

Visor hack

Exploits incorrect rollover of memory address. Microsoft's strategy for halting the system in the event of a "panic" event during the boot process (i.e., the hash for decrypting 2bl is incorrect) was to put the code to hide the MCPX ROM at the very end of the ROM itself, which is mapped to the top of addressable memory, and rely on the CPU to halt when the instruction pointer rolls over from 0xFFFFFFFF to 0x00000000. Incredibly, Microsoft missed that this behavior was specific to AMD's x86-compatible CPUs, which were used during the development process. In fact, the Intel CPU that ended up in retail units will happily continue execution at 0x00000000.

Visor's hack used Xcodes to write a jump into a location in flash memory at the very beginning of the address space and forced the MCPX ROM to panic by rewriting bytes at the end of 2bl. When the MCPX attempts to validate the 2bl, it will fail and attempt to "fall through" the memory space until the system halts, which never actually happens and the CPU will continue to execute the injected code that jumps into flash.

MIST hack

Exploits error in xcode interpreter security check. MCPX 1.0 contains code intended to prevent an attacker from using Xcodes to turn off the Xcode interpreter, which is normally accomplished by setting a bit in memory used by the PCI bus to set device configuration, directing the mapping of memory to the top of memory from the MCPX's ROM to flash. The interpreter will reject Xcode that attempts to modify data at this address, but neglects to consider the behavior of the PCI controller, which only utilizes the lower 24 bits of a memory address. Consequently, it is still possible to toggle the necessary bit and turn off the MCPX's secret ROM by using a "fake" address -- the desired address with the upper bits modified so that the interpreter's check will not catch that we are hiding the secret ROM.

A similar attack is possible by abusing the Xcode interpreter's ability to outputting the necessary code to hide the secret ROM to the appropriate I/O port, which the interpreter does not attempt to stop.

A20M# hack

A jumper wire hack to enable A20

Uses a legacy x86 feature (beginning with 286 CPUs) that relied on a gate on address line 20 (A20) to determine whether the code execution should roll over to the lower 64kb or continue on into higher memory addresses. This feature still existed in the CPU used in the Xbox. By pulling down the A20 gate, an attacker can effectively modulate an address so that the system will point to a location in memory below the addressed location. For instance, with the A20 gate pulled down, the address 0xFFFFFFFF would be translated to 0xFFEFFFFF, which on the Xbox would continue code instruction at a location in flash.

RC4 attack (MCPX 1.0 only)

Microsoft uses the last bytes of the decrypted 2BL to check the integrity of the 2BL. However, RC4 does not have any feedback which means changes in the 2BL will not reflect in the last couple of bytes which are checked. As such, the 2BL can be freely modified, as long as the last couple of bytes still match what the MCPX ROM expects.

This can be used to take over the 2BL entry point.

When the attack happens, the MCPX ROM is still visible, making this a very powerful attack.

This attack is described by Michael Steil in his Google talk, “Hacking the Xbox Security System.

TEA attack (MCPX 1.1 only)

TEA, which is only used in MCPX 1.1, can not be used as a hash in Davies-Meyer mode [1][2]. And yet, Microsoft used it that way.

The original attack uses the 5 bytes at 0xffffd400 (FBL entry point) which are E9 83 01 00 00. This is jmp 0xffffd588 (which is a jump within the flash region).

When flipping the highest bit of the operand DWORD (at 0xffffd400, mind your endianess) this will become: E9 83 01 80 00. This is jmp 0x7fd588 (which is a jump into the RAM region). For the attack to be successful, the highest bit in the DWORD at 0xffffd404 also has to be flipped.

The RAM can be controlled using the x-code command to write to RAM. So the idea is to copy a program from Flash to RAM using x-codes. Then the FBL / 2BL is modified to jump into said RAM region by flipping a bit of a jump operand (as described above). The 2 bit flips will not change the hash of FBL / 2BL as TEA is broken.

As such, the FBL verification will succeed, the MCPX ROM will hand control to the FBL which will then jump into the attacker controlled RAM.

When the attack happens, the MCPX ROM is still visible, making this a very powerful attack.

The TEA algorithm and exploit are also described in more detail in Bunnie's book (Page 109 and Page 142).

Dashboard

Audio hacks

Font hacks

Analysis of "Bert & Ernie" font-exploit.

Easter-egg exploit

Savegames

Savedgames can be used as an exploit method, but care must be taken for most games are verifying digital signatures of savedgames ^{[citation needed]} [3]

007: Agent Under Fire

Analysis of this savegame-exploit.

Frogger Beyond

Not much is known why this game was in the list, 22C3, page 85 The game isnt shown in the final presentation at 22C3 (neither are Mechassault nor SplinterCell).

In 2022, Artem Garmash published a blog post describing an approach to exploiting Frogger Beyond.

MechAssault

Exploit runs a modified version of Xbox Live Update to execute a paylaod.

Tom Clancy's Splinter Cell

Tony Hawk's Pro Skater 4

Grimdoomer discovered a savegame exploit in THPS4, shared it on Discord and was later included with the Rocky5 softmod installer. a video demonstrating the game trigger (custom skatepark)

10-4-2017 it's just shell code I injected into the game save/ granted this save is slightly more complicated than the others and requires a small "loader" that is just a memcpy basically it's literally as simple as a buffer overflow...I just looked for null terminated strings and fuzzed them then when I got a crash I looked in teh xbe to figure out what was going on. yeah it's literally just a stack overflow - grimdoomer

another website talking about his exploit. xbmc4xbox.org.uk

Attack ideas

Notes

• 17 Mistakes Microsoft Made in the Xbox Security System
• A list of some exploit implementations