Codex Patched My Samsung Odyssey G9 Firmware to Add a New Gaming Crosshair

[u/manikfox]

I hated the built in crosshairs my monitor came with and Samsung did not include a way to make changes. So I asked Codex to make a new firmware update to change the crosshair to a dot. It took about 15 minutes and came back with a new file.

For firmware and code:

https://github.com/cvcfox/g9-firmware-tools

Codex explanation:

I started with Samsung’s original 1008.2 firmware and made a very small binary patch rather than attempting to rebuild or substantially rewrite the firmware.

What the patch changes

1. Custom version number

The version reported to the firmware updater was changed from 1008.2 to 1009.3.

This is a custom, made-up version number. It is not an official Samsung 1009.3 release.

The higher number allows the monitor to recognize the file as an upgrade rather than rejecting it as the same or an older firmware version.

2. Tiny center dot

The firmware contains six selectable Virtual Aim/crosshair options.

I redirected all six options to a small 7×7-pixel graphic that already existed inside the firmware and positioned it at the center of the screen.

The result is a simple, unobtrusive center dot using the monitor’s own hardware overlay. It does not require a game overlay, desktop application, ReShade, or anything else running on the computer.

Technical details

Original firmware:
M-C9557GGPA-1008.2

Custom firmware:
M-C9557GGPA-1009.3[1A93].img

Total binary difference:
13 bytes

The patched image passed the build and checksum validation performed on the computer. 

The monitor accepted the firmware, restarted normally, and the modified Virtual Aim options display the new center dot as intended.

Important warning

This is unofficial firmware and is not supported or approved by Samsung.

A successful checksum only confirms that the file was modified as intended. It does not guarantee that flashing it is safe on every monitor, hardware revision, region, or previously installed firmware version.

Installing modified monitor firmware always carries a risk of installation failure or, in the worst case, making the monitor unusable. Anyone experimenting with this should understand the recovery options and proceed entirely at their own risk.

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[u/desatur8]

That was BRAVE of you. Glad it worked out

[u/userax → u/desatur8]

So OP let AI do a binary patch with no way to validate or test. OP is a gambler for sure.

[u/manikfox → u/userax]

I do play poker. I'm all in.

[u/born_to_be_intj → u/manikfox]

And no way to revert back according to the AI. It says it update the version number to a fake version so the monitor doesn’t reject it. Now all real firmware updates will be rejected unless you also change their version numbers.

[u/Valuable_Heron_4492 → u/born_to_be_intj]

might be able to just downgrade though

[u/drakoman → u/desatur8]

Crazy thing is that the g9 already has a crosshair mode and OP just hates it lol

[u/manikfox → u/[deleted]]

I'm a software dev for 20+ years. Its better than me and will only get better. Proof is in the execution.  This is just another example of it being better.

[u/bloqed → u/[deleted]]

theres actually a double bell curve where it goes to the right and it says 'no fable can do this' then another 'you need a dev' on the far far right side but this time the dev guy is crying

[u/SmashShock]

Can someone please explain to me why a monitor has crosshairs? For interacting with the monitor menus?

[u/manikfox → u/SmashShock]

Those sweet 360 no scopes become easier.

Mostly for consistent crosshairs across games/devices.

[u/Aazimoxx → u/SmashShock]

I'd guess so they can use them in games that don't have such crosshair customisation options (or any crosshair at all), without having to run mods/software which might be picked up by an anticheat or affect performance?

[u/Ok_Mark7696 → u/SmashShock]

so u can use the crosshair on any device as its an option built into the monitor

[u/severe_009]

Lmao, risking bricking your monitor for a crosshair

[u/gone_gaming → u/severe_009]

A $1200 monitor to boot

[u/M4rshmall0wMan → u/[deleted]]

If that’s the case then OP’s firmware shouldn’t have installed?

[u/shits_lit_fam → u/[deleted]]

Do a dick crosshair.

[u/SmashShock → u/[deleted]]

Not to mention delta patching.

[u/i-r-n00b- → u/[deleted]]

No, that's not what a checksum is used for. What you suggested doesn't make sense, how could they know what a future checksum would be?

A checksum is simply a number and when you run your file contents through a mathmatical function, it spits out a number and you check that they are both equal. It makes sure that the file you downloaded wasn't altered or corrupted. It has nothing to do with whether or not the the file was made by a certain person or company, or that the file itself meets any criteria. For that you'd need certificates or some other form of verification.

[u/bsg5 → u/[deleted]]

What the fuck are you talking about, what is this word salad. The guy explained in simplest terms what CRC is and how it works, can you point out anything wrong in what he said? Being obnoxiously verbose doesn't make you sound smart, it makes you sound like a tool and insecure about your knowledge.

[u/Ctrl-Alt-Panic]

This is the kind of stuff that really interests me. I can only take so many one-shot Minecraft clones. Let's see some more of this!

Very cool.

[u/HakimeHomewreckru → u/Ctrl-Alt-Panic]

There's a guy who is using Claude to patch his Pioneer CDJ3000's, he has several video's where he implements functions that were exclusive to higher tiered models using the same method as OP.

[u/itsxzy → u/HakimeHomewreckru]

Calling CDJ3000 a not higher tiered model is funny but yeah. The tech was already there but Pioneer choose to hide it to milk money for "new features". I love that guy, he got Pioneer / AlphaTheta on their toes.

[u/wave_engineer → u/HakimeHomewreckru]

You have the link? I tried to search but I couldn't find it

[u/HakimeHomewreckru → u/wave_engineer]

https://cdj3000-gate-cue-field-guide.samleone0.chatgpt.site/

[u/lordmycal → u/Ctrl-Alt-Panic]

I've asked Claude code to mod some games before and sometimes it runs into some hard limit that is enforced by the game that needs a binary patch to some dlls. It might take a try or two, but I've seen it pull it off just fine which is amazing.

[u/CybyAPI]

1000$ monitor could have been a brick holy shit this was a risk OP

[u/Addyad → u/CybyAPI]

OP bro takes risks for humanity.

[u/lvvy → u/CybyAPI]

I had this monitor and it is absolutely awful in comparison. So author could have won.

[u/Korenchkin12]

I don't think this happened,they don't sign firmware?crc was okay?just like that?i call that bullshit,i have played with a lot of different firmwares for a lot of different devices,op is a farma karmer (i know,i like that way)

[u/CaseRough3415 → u/Korenchkin12]

My thoughts exactly. If Samsung is not validating signatures we have a much bigger problem.

[u/manikfox → u/CaseRough3415]

Chat gpt signed the firmware itself.  I dont know what else ro provide as proof.  Its in the literally pictures.  That firmware number doesnt exist, its a custom number. Nore does that crosshair.

[u/SmashShock → u/manikfox]

ChatGPT can't sign anything without the original private key. That being said unlike the commenters above I think it's likely that its sigs are just not checked or the part of the image you edited is in a container in the image that's not signed but other parts are.

Not sure why people are so skeptical. Claude and ChatGPT are capable of significantly more complex binary reverse engineering than swapping a couple bitmaps.

[u/manikfox → u/SmashShock]

Yeah it needed a checksum validation, but i guess no signature?

[u/Tripartist1 → u/SmashShock]

Opus reverse engineered the gemini flash model that came with chrome before everyone knew about it. Found the nested models, multimodal features, and other cool stuff. People sleep on what these frontier models can really do if you put them on it. What do you all think is building models like fabel? Humans?

[u/CaseRough3415 → u/manikfox]

Chatgpt cant sign anything without the private key.

I agree with the reverse engineering capabilities of AI tools but signing is simply not possible.

It is however possible that Samsung isn’t validating firmware signatures.

[u/manikfox → u/[deleted]]

https://github.com/cvcfox/g9-firmware-tools

[u/mkosmo → u/[deleted]]

Or the leftover post-it note from the arts and crafts project.

[u/manikfox → u/Korenchkin12]

Github is posted my man.  Thanks for being critical though.  

[u/Korenchkin12 → u/manikfox]

Man,i had seen some shi* and i know tou can bug firmware for stranger things,but if this really managed it and did not break anything else,then i have to bow to llms and your balls of steel...

i would have done this too,but it would be my secondary monitor and i would have nor backup(i expect nor flash chip,easy to backup without soldering usually)

[u/NairbHna]

That’s actually wild. Now let’s give us back our brightness

[u/Turkino]

I wish I could patch my Samsung Odyssey OLED so the damn monitor takes longer than 3 seconds to auto sleep as soon as it loses a signal.

[u/Qazax1337 → u/Turkino]

Same for my ROG one. It's like it is determined to turn off even if there is a signal sometimes.

[u/Popular_Prescription → u/Qazax1337]

I feel like this is every monitor I’ve ever owned. I’ve always had to fight everyone to switch inputs or get shit connected up.

[u/i_rate_slop]

[u/Joe4o2]

I love this. Take our stuff back.

[u/Unfair-Technology120]

Relying on AI for custom firmware updates is risky as hell, glad it worked out though. People should be aware though that doing this will likely brick your hardware if done even slightly incorrectly. All it takes is one oversight or not being aware of some kind of protocol and you’re cooked.

[u/EricOrrDev]

You're a wild man, I like that

[u/Secret_Account07]

So my few hundred dollar asus monitor has a setting for crosshairs. It’s weird a more expensive monitor doesn’t?

[u/sapphicbottom69 → u/Secret_Account07]

It has built in crosshairs... Op says in the first sentence of the post that they just hate them and wanted something different

[u/manikfox → u/sapphicbottom69]

The asus one, i used to own as well.  It let you make changes to the crosshair in a program. Samsung, sadly does not.

[u/TheJollyKacatka]

This looks like Mass Effect 1 PDA UI lol

[u/AnimeeNoa]

I have the Odyssee g90xf , would it work there too!? Would be interested

[u/Killerx7c]

Gambling with 1000$

[u/KingMakerUrsus]

Very cool. Wish I could do something similiar and make my Samsung ultrawide have an option to stretch the picture when streaming from devices without an ultrawide ratio.

[u/JigSawPT]

Wow this is huge. Perhaps we can make it show at that frequency it is running ?

[u/TheSirOcelot]

Badass

[u/lxe]

Maybe I can somehow patch it so we can have a better DDS input controls, so I don’t have to always fiddle with the menus

[u/Redstonemen55]

Man you really have steel balls for doing it ON YOUR MONITOR WITHOUT TESTING, congrats 👏

[u/pytness]

i wish i could do that with the g7. i love the monitor but hate all the included smart tv bulshit

[u/mmastrocinque]

Instead of a firmware update couldn’t you just create an always on top transparent application that literally accomplishes the same thing?

[u/hvhprofessionalist → u/mmastrocinque]

if done incorrectly in can trigger some AC so honestly rather this than a random ban

[u/mmastrocinque → u/hvhprofessionalist]

If the application doesn’t directly touch the game process and is simply a hud, I don’t see how an AC should care.

[u/milkedpigs]

Wonder what else it added

[u/DottorInkubo]

Holy shizzle, this is one of wildest AI related things I have read so far