“Good Enough” Emulation: Because Your Fuzzing Sucks and You’re Too Lazy to Fix It

Oh for fuck’s sake. Another day, another research paper from some wankers who think they’ve reinvented the goddamn wheel. This time it’s Talos Intelligence – those Cisco-backed bellends – who’ve decided that fuzzing multi-threaded applications isn’t quite painful enough, so they’ve come up with a “solution” that’s about as elegant as using a sledgehammer to crack a walnut. Except the walnut is a hypervisor and the sledgehammer is half a fucking emulator.

The problem? Multi-threaded code is a bastard. You fuzz it normally and you get more non-deterministic crashes than a Windows 95 box on a hot day. Every fucking thread is fighting over memory like seagulls over chips, and your fuzzer can’t tell if it found a bug or just the cosmic rays hitting the RAM at the wrong moment. It’s enough to make you want to strangle the last developer who thought “you know what this needs? More threads!”

So these geniuses – and I use that term with the same affection I reserve for printer manufacturers – decided to ignore the problem entirely. Their “brilliant” insight: just fuzz one fucking thread. I know, revolutionary, right? They call it “GoodEnoughEmulation” because apparently “Lazy Bastard Emulation” didn’t make it past marketing.

Here’s how this masterpiece of half-arsed engineering works:

First, they use Intel Processor Trace (PT) to stalk a single thread like a creepy ex, logging every basic block it touches. They build a “code forest” – which sounds like somewhere you’d dump the bodies of junior developers who’ve asked too many stupid questions. Then they extract all the memory reads and writes, creating a memory layout that looks like a Jackson Pollock painting but somehow works.

Next, they fire up Bochs – an emulator so slow it makes continental drift look frantic – but they only give it the code forest and memory snapshot. No syscalls. No other threads. No fucking reality whatsoever. It’s like putting a brain in a jar and asking it to do your taxes. But here’s the kicker: it actually works. The vulnerabilities don’t give a shit if the rest of the system exists – they just need the right code to execute and the right memory to corrupt.

They aimed this steaming pile of ingenuity at VMware Workstation’s network stack – because nothing says “weekend ruiner” like trying to crash a hypervisor. And wouldn’t you know it, they found six unique bugs. One of them was CVE-2024-22251, a stack-based buffer overflow that scored an 8.1 CVSS. That’s not just a crash – that’s a “remotely own the host machine while cackling maniacally” level of fuck-up.

The best part? This shitty half-measure approach actually beats full system emulation because it’s not busy emulating every goddamn thing under the sun. It’s focused. It’s lean. It’s like the difference between a surgical strike and nuking the site from orbit – except the surgical strike is performed with a rusty spork and a bottle of cheap whiskey.

Look, I’m not saying these researchers are heroes. They’re still the kind of people who think writing Python makes them a fucking systems programmer. But credit where it’s due – they’ve proven that sometimes “good enough” is exactly that. You don’t need to emulate the universe to find a buffer overflow. You just need to emulate enough of it to make the bug show its ugly face.

So next time some pointy-haired boss asks why your fuzzing isn’t finding bugs, tell them you’re using “GoodEnoughEmulation.” It’s not laziness, it’s a fucking research-backed methodology. And if they believe you, they’re too stupid to understand the answer anyway.

Now if you’ll excuse me, I’ve got a batch of junior security researchers to traumatize with my collection of crash dumps and broken dreams.

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Link: https://blog.talosintelligence.com/good-enough-emulation/

Anecdote: Just last week some tosser from marketing asked me why we couldn’t “just fuzz everything at once” to save time. I told him I’d get right on it, then redirected his laptop’s DNS to a server that only resolved to 127.0.0.1 and watched him try to “debug” why his “internet was broken” for three hours. He finally rebooted seventeen times before calling helpdesk, who I promptly told to escalate to “the ghost in the machine.” The ticket’s still open. Some problems, like multi-threaded race conditions, are best left unsolved.

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