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submitted 1 month ago* (last edited 1 month ago) by atrielienz@lemmy.world to c/technology@lemmy.world

"According to the research published by Hackmosphere, the technique works by avoiding the conventional execution path where applications call Windows API functions through libraries like kernel32.dll, which then forwards requests to ntdll.dll before making the actual system call to the kernel."

Additional Information:

https://www.hackmosphere.fr/bypass-windows-defender-antivirus-2025-part-1/

https://www.hackmosphere.fr/bypass-windows-defender-antivirus-2025-part-2/

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[-] Cephalotrocity@biglemmowski.win 0 points 1 month ago

They also suggest organizations deploy additional security layers beyond Windows Defender, particularly solutions that can monitor behavior at the kernel level.

Anything like this for the typical home user?

[-] 0x0@lemmy.zip 4 points 1 month ago

Sure, bring back Crowdstrike, that went well...

Btw I wasn't aware XOR was encrytion...

[-] Zwuzelmaus@feddit.org 1 points 1 month ago

Btw I wasn't aware XOR was encrytion...

It's even better than ROT13, because you always need to apply ROT13 twice for getting the good results...

[-] Neverclear@lemmy.dbzer0.com 1 points 1 month ago* (last edited 1 month ago)

XOR cleartext once with a key you get ciphertext. XOR the ciphertext with the same key you get the original cleartext. At its core this is the way the old DES cipher works.

A bit of useful trivia: If you XOR any number with itself, you get all zeros. You can see this in practice when an assembly programmer XOR's a register with itself to clear it out.

[-] Quazatron@lemmy.world 1 points 1 month ago

That's how it was done in the old days to save a few cycles in Z80 assembly. XOR A instead of LD A, 0.

[-] InverseParallax@lemmy.world 1 points 1 month ago

I use that daily in my accelerator work.

Once you learn the trick, you just use it naturally.

[-] Malfeasant@lemm.ee 0 points 1 month ago* (last edited 1 month ago)

an x86 assembly programmer

Ftfy. not all CPUs have an xor register with itself instruction.

[-] QBertReynolds@sh.itjust.works 1 points 1 month ago

There are a lot more architectures than just x86 that are capable of XORing a register with itself (ie. ARM and RISC-V), and if you took OP to mean the accumulation register specifically, pretty much all CPUs going back as far as I can think have had that functionality.

[-] Malfeasant@lemm.ee 0 points 1 month ago

Yes, but it's not universal that xoring a register with itself is more performant than simply loading it with 0.

[-] QBertReynolds@sh.itjust.works 2 points 1 month ago

I never made that claim, nor did the person you corrected.

[-] Malfeasant@lemm.ee 0 points 1 month ago

Yes, but that's why x86 assembly programmers do it...

[-] QBertReynolds@sh.itjust.works 1 points 1 month ago

No argument there. It's also why it's done in ARM, 8080, SM83, z80, 6502, and basically every other assembly language. It's only not done in RISC-V because you can fold 0 into any instruction as an operand, therefore eliminating the need to clear a register before an instruction.

So why correct the person with a more narrow claim that makes it seem like xor being faster than loading zero is a rarity in CPU architectures? If I said "birds can fly", and your response was "eagles can fly. Ftfy. Not all birds can fly", it would be both true and utterly unhelpful.

[-] Malfeasant@lemm.ee 0 points 1 month ago

Hey look, I'm good at something.

[-] mbirth@lemmy.ml 0 points 1 month ago

Wasn’t there something a few months ago about Microsoft handing out secret API calls to developers of other antivirus products so they can quietly disable Defender during the installation of their product? Some guy had this reverse engineered from an installer…

[-] Brkdncr@lemmy.world 1 points 1 month ago

It’s not a secret. It’s a regkey. You need privs to do it though.

this post was submitted on 12 Apr 2025
2 points (75.0% liked)

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