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Randar: A Minecraft exploit that uses LLL lattice reduction to crack server RNG

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Re: Randar: A Minecraft exploit that uses LLL lattice reduction to crack server RNG

#31

Post by squigz »

chc4 wrote: post #15

LLL lattice reduction is the same algorithm that can be used for cracking PuTTY keys from biased nonces from the CVE a few days ago. 'tptacek explained a bit about the attack (and links to a cryptopals problem for it, which I can almost pretend to understand if I squint) https://news.ycombinator.com/item?id=40045377 In a similar vein, the SciCraft minecraft server had a creeper farm which used some sort of black magi…

> some sort of black magic

> which I can almost pretend to understand if I squint

This is me and all cryptography :D

Re: Randar: A Minecraft exploit that uses LLL lattice reduction to crack server RNG

#33

Post by reactordev »

timdierks wrote: post #23
dzdt wrote: post #9

Back in 1999-2000 there was an "International RoShamBo Programming Competition" [1] where computer bots competed in the game of rock-paper-scissors. The baseline bot participant just selected its play randomly, which is a theoretically unbeatable strategy. One joke entry to the competition was carefully designed to beat the random baseline ... by reversing the state of the random number generator and then predicting…

That's me! Thanks for pulling up the quote from long ago: > "With his obvious technical skill, and his "cheat early and often" attitude, Tim could have a promising career as an AI programmer in the computer games industry. :)" Instead took a path of security, authoring the TLS RFC and principal engineer in Google security. Thanks for the flashback.

So what you’re saying is, if you can’t beat em, join em? /s

I’m actually a bit relieved they have you on the team. Considering what they (Google) know about us all.

Re: Randar: A Minecraft exploit that uses LLL lattice reduction to crack server RNG

#34

Post by er4hn »

This appears to be a State Compromise Extension Attack (https://en.wikipedia.org/wiki/Random_number_generator_attack) which is something that PRNGs that are not CSPRNGs can be subject to.

At this point it feels like having PRNGs be defaults is just not that safe of a thing to offer in libraries. Like defaulting to allow TLSv1.0 or blowfish in 2024.

Re: Randar: A Minecraft exploit that uses LLL lattice reduction to crack server RNG

#35

Post by BarryMilo »

joshu wrote: post #26
dzdt wrote: post #9

Back in 1999-2000 there was an "International RoShamBo Programming Competition" [1] where computer bots competed in the game of rock-paper-scissors. The baseline bot participant just selected its play randomly, which is a theoretically unbeatable strategy. One joke entry to the competition was carefully designed to beat the random baseline ... by reversing the state of the random number generator and then predicting…

I submitted the optimally bad entrant the first year, cheesebot. https://web.archive.org/web/20180719050236/http://webdocs.cs...

I can't believe they didn't say anything about your solution! How did it work?

Re: Randar: A Minecraft exploit that uses LLL lattice reduction to crack server RNG

#36

Post by hot_gril »

cedws wrote: post #19
dzogchen wrote: post #18

I loved playing on 2b2t, until it got too popular all of the sudden when a YouTuber did a video on it. 2b2t (an anarchy servers in genral) are Minecraft the way it is meant to be played.

I haven't played Minecraft for many years but I'd argue the way it's supposed to be play is an old version from like 10 years ago with a tech modpack like Tekkit. Back then, there were open servers where communities built cities with no grief prevention because people trusted each other.

When I was a kid, I ran a public server with Logblock and anticheat but no other plugins, so it was basically vanilla for anyone who wanted to play nice. People loved it.

Re: Randar: A Minecraft exploit that uses LLL lattice reduction to crack server RNG

#37

Post by zzzzzzzzzz10 »

sebzim4500 wrote: post #22
pclmulqdq wrote: post #5

I have seen a lot of interesting and funny RNG issues, but this is one of the most sophisticated exploits for the least payout. A wonderful work of art.

If they had sold the items they could have probably made some money (maybe $1000s?). Still a small payout considering the amount of work, of course.

You can make much more by selling items on 2b.

This is not little payout, it sounds to me like one of the most significant exploits in anarchy minecraft history, possibly even more than nocom.

Re: Randar: A Minecraft exploit that uses LLL lattice reduction to crack server RNG

#38

Post by zzzzzzzzzz10 »

asddubs wrote: post #10
bee_rider wrote: post #7

Pretty cool exploit. The idea of a free for all bug abusing server is pretty neat, a whole ‘nother level of the game. I guess this is what “actually fighting” (rather than just using in-game battling mechanics) would look like if the metaverse really happened ever.

I also quite liked the idea of a true anarchy server (from a gameplay perspective), but on 2b2t in practice this looked like a lot of the n-word being said in chat, so I stopped playing.

You can avoid this using chatfilters. Players who spam slurs are not worth talking to anyway.

But I agree that there are far better anarchy servers than 2b around.

Re: Randar: A Minecraft exploit that uses LLL lattice reduction to crack server RNG

#39

Post by ryanisnan »

pclmulqdq wrote: post #5

I have seen a lot of interesting and funny RNG issues, but this is one of the most sophisticated exploits for the least payout. A wonderful work of art.

Indeed! I love seeing how the seemingly innocuous decisions by Mojang devs are being abused here, so freaking cool.

Re: Randar: A Minecraft exploit that uses LLL lattice reduction to crack server RNG

#40

Post by pclmulqdq »

zzzzzzzzzz10 wrote: post #37
sebzim4500 wrote: post #22

Earlier quoted context omitted.

If they had sold the items they could have probably made some money (maybe $1000s?). Still a small payout considering the amount of work, of course.

You can make much more by selling items on 2b. This is not little payout, it sounds to me like one of the most significant exploits in anarchy minecraft history, possibly even more than nocom.

RNG vulnerabilities are usually really bad in terms of the systems they compromise. It often means exposure of keys, huge numbers of jailbroken devices, or something similar. Making at most tens of thousands of dollars in Minecraft with one is sort of cute and fun in comparison.

Of course, I could be underestimating this by a lot.

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