101
Windows Defender Anti-virus Bypassed Using Direct Syscalls & XOR Encryption
(cybersecuritynews.com)
this post was submitted on 12 Apr 2025
101 points (95.5% liked)
Technology
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Anything like this for the typical home user?
Sure, bring back Crowdstrike, that went well...
Btw I wasn't aware XOR was encrytion...
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.
Apple had this undocumented function for screenshotting back on iOS 3.1, and kind of let you use it while waiting for better frameworks in iOS 4.0
At some point they started rejecting your app automatically if they found the symbol for that function in your app. I didn't want to leave my 3.1 users in the dust for no reason, so I did the same trick to obfuscate the symbol name before dynamically linking it in.
It worked right up until they stopped supporting iOS 3.1 completely.