New PS2 exploit found, uses official Yabasic demo discs as its entry point

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The gaming community may be itching to read all the latest news about Sony's upcoming console, but that doesn't mean homebrew enthusiasts have left the previous generations behind just yet. In fact, one developer in particular (@CTurt, a name already familiar to those in the PS4 scene) has decided to go back a whopping 19 years to revisit the PlayStation 2 not for a quick nostalgia dive, but to crack it even further than it's ever been!

As a lot of you readers may know by now, Sony's best-selling console is by no means a stranger to hacks: a plethora of modchips, software exploits and other types of clever tricks to bypass the platform's security have popped up over the years, all of them with their own methods and pros/cons. However, most of them require either purchasing some pieces of hardware or having a pre-modded console at hand to later pass an exploit over to your own, which is by no means ideal for a multitude of reasons. But this is about to change starting today, as @CTurt has managed to find an exploit which only needs a PS2 Yabasic demo disk to work.

The exploit consists of two stages: the first overflows one of the interpreter's built-in functions and gains arbitrary code execution, while the second is a payload that launches an ELF from a medium available to the system (the repo includes one that loads the FIFA demo bundled with a specific revision of the disc, however, someone could technically choose whichever executable they want - even on a different/burned CD). Support for USB/HDD drives and loading ELFs over the network is also reportedly possible, but no compatible payload has been written for those yet. Everything said so far only requires a stock PlayStation 2 and an aforementioned Yabasic demo disk (something many European owners may already have as Sony originally included one with the consoles to avoid EU import taxes) so this should not only open up the doors to hacking & homebrew for many more people, but the exploit also works with late Slim models that don't support FreeMCBoot at all!

There are, however, a few things you should keep in mind. First and foremost, while everything is already in a working state and the code has been made public, it's not really that user-friendly yet: you need to compile the exploit yourself and, as previously stated, some otherwise useful payloads are still missing and will be added sometime in the future (other devs are welcome to make their own contributions!). Secondly, while most demo disks containing Yabasic are supported (serials PBPX-95204, PBPX-95205 and PBPX-95506), one of them is still not compatible as it uses a different executable version and the developer wasn't able to get their hands on it (serial PBPX-95520 - if you have it, please consider contacting the dev!). Lastly, those discs have only been produced for PAL consoles, so NTSC PS2 cannot take advantage of the exploit due to region locking.

Here is the usage guide included in the README:
Install the PS2DEV toolchain (really you just need a MIPS compiler), place your assembly payload in payloads/name.s and run make to build it into a Yabasic exploit.

On PS2, run the %lg patch corresponding to your disc first. EG: for PBPX-95205 that will be in out/patches-95205.yab.

Then you can run your payload (located at out/name.yab).

If your payload writes a value, you'll need to run the feEgG patch, and then you can run the debugger program to print it (both in out/patches-version.yab).

Feeling experimental? You can find PS2-Yabasic-Exploit's GitHub repo by clicking the source link below! You can also find out more about how the exploit works by reading the technical writeup here.

:arrow: Source
 
Last edited by RattletraPM,

raxadian

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Both of my PS2s are chipped, but one won't play DVDs movies. Can you make those models play DVD movies with this exploit?
 

Sakitoshi

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Both of my PS2s are chipped, but one won't play DVDs movies. Can you make those models play DVD movies with this exploit?
if the chip in question is a matrix or a clone of it you can press circle before turning on your ps2 and hold it until you see the cubes and smoke, that'll tell the chip to force dvd video or ps1 mode (depends if the disc is a dvd or cd).
 

smf

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Is there a simple payload that will boot an elf off usb?

Otherwise beyond it being a cool exploit, it's going to be pretty useless.
 

gamesquest1

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Well, you only have to do it once, run the FMCB (or FHDB) installer and off you go.

I guess you have to type it out manually, but it's not that long. I expected it to be more complex. No idea what he means by that patch though. I guess if you wanted to load homebrew with this, you would have to disc swap to a burned disc containing your .elf file. Unless someone can figure out a way to load directly from USB with the exploit, if that's even possible.
im assuming to make a usb loader it would require some trickery to basically code the usbmass storage feature....unless the yabasic demo already has that irx loaded for the usb keyboard support etc, not really all that clued up on how exactly the PS2 mass storage function works but i would imagine it would require the driver to either be already loaded or manually loaded into the system via yabasic, im just assuming the mass storage feature isn't already loaded else CTurt probably would've just had the sample load the elf via USB, so the other alternative would have to be a huge input of data to get mass storage function into yabasic which would require a lot more manually typing, unless you used some sort of arduino to auto type the entire code or spend a few hours inputting random data into yabasic hoping that you didn't screw up and leave out a number or bracket somewhere and have to start all over again, but at that point most people would probably be better off buying a pre-loaded FreeMCboot memory card
 
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nolimits59

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Pretty sure i have one of theses demo disc, anyone got the PS2 PAL Primal pack to tell me if it's a good demo disc for that exploit ? :)
 

Dax_Fame

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I love to read things like this about "classic" consoles... it's crazy to me to refer to the PS2 as classic now but it certainly is!

Keeping things alive :yayps3:
 

71r3n

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So wheres the deal?
I remember us using a burned disk, that u had to load before putting in the actual game and it worked.
 

ILuvGames

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raxadian

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Sorry your PS2 doesn’t play DVDs. Maybe you could set aside $20 and get a DVD player. They’re really cheap now.

One PS2 does and the other does not, and I do have a DVD player.
if the chip in question is a matrix or a clone of it you can press circle before turning on your ps2 and hold it until you see the cubes and smoke, that'll tell the chip to force dvd video or ps1 mode (depends if the disc is a dvd or cd).

Thanks, I will try it out.
 
Last edited by raxadian,

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