38C3 - Dude, Where's My Crypto? - Real World Impact of Weak Cryptocurrency Keys

[Translated by Pekka P]

(KYBS2004 course assignment at JYU.FI)

♪ (38C3 intro music) ♪

*clap*

Hey everyone,

it's an honor to be here,

and it's great to see so many familiar faces

and so many new faces.

I know it's 11 a.m. on the last day,

so I'm impressed to see so many people here.

And welcome to the chaos of everything.

I'm John Nolte.

I'll be speaking today.

Someone who's not on stage

but is in each and every slide here

is Christian, the lead researcher

for the MilkSAD team.

I'm going to be talking about the story of MilkSAD,

the story of researching cryptocurrency wallet theft

in 2023,

and very happy to do so.

Very honored to be here.

Here's some of their names.

You see them as names.

I see them as friends, as trusted colleagues,

ex-coworkers,

random people I've never met

on the internet.

The only thing we had in common for the most part

was we were all in the same Matrix channel

diving into a problem.

Listeners, beware.

I might not be 100% factual

with everything I say.

I am excited to be here,

a little nervous to be here.

And there's a lot of information to go over.

So, it's too much for a 30-minute talk,

too much for a 45-minute talk.

And there's just a lot of research that the team did.

It's well represented at MilkSAD.info.

You can see the talk notes,

slash 38C3.

You can scan this QR code.

Trust me, it's safe.

I hope.

Yeah.

And let's go over this talk.

We're going to get a little intro to cryptocurrency wallets.

Who here has ever heard of cryptocurrency?

Okay.

There's people that drank their herbamatas

and their coffee today.

It's nice to see some reactions.

We're going to talk about a theft

that happened about a year and a half ago

in July of 2023.

Then some of the additional work we did

and a lot of the ethical dilemmas and conflict

inside and outside of the team.

How many here are security researchers?

I'd like to know a little bit about the audience I'm addressing.

Okay.

So, there's a few.

So, there might be people who haven't been exposed

to discovering vulnerabilities in the wild

and all the things that can happen there.

So, I'll make sure to cover that.

And then we'll also just talk about the story

of people losing money on the internet

with magic internet money

and maybe ways to defend

against that type of thing.

So, to start,

let's talk about cryptocurrency wallets.

Okay.

Another question.

Who here has ever used a cryptocurrency wallet?

I feel so sorry for you.

It's so hard

and there's just a lot of stuff that happens when you set up a wallet.

A lot of things aren't well explained.

You just kind of go,

you install your app or run your software.

You get sometimes 12 magic words

or 24 magic words and you put them in your pocket.

You, you know, take a picture

and put that up on your cloud storage.

You know, really no one walks you through

what a safe way to do cryptocurrency wallet stuff,

you know.

So, it can be really confusing.

At the end of the day, what happens

is you're trying to capture some type of entropy.

You're trying to generate some type of random seed.

And from that seed, derive a bunch

of private keys and public keys.

A lot of cryptographic operations and cryptocurrencies based on asymmetric cryptography.

So, there's a public-private key pair.

Your public key, you can share to the world.

They can identify you by that key.

So, you know, be warned.

It is a tool to track that particular address,

that particular identity.

And then there's a private part.

And it really is like a private part.

Like, you don't really want to show that everywhere.

So, you know, there's these public-private keys.

And long ago, people were just generating single keys

and storing them, backing them up.

And it was quite a hassle.

So, the Bitcoin folks and community

came up with this improvement proposal, BIP39,

where they're like,

why don't we keep this little seed,

this magic little seed of entropy into words,

you know, mnemonics,

mnemonic seed phrases.

It's a lot easier to remember 12 words or 24 words

than it is to remember a bunch of random characters

that are maybe base 58 or base 64 encoded.

And so, BIP39 was a way to make things a little bit more human-readable

to keep a secret safe.

And from that secret, you could derive a bunch of private keys.

And BIP32 is the Bitcoin improvement proposal, number 32,

to have hierarchical deterministic wallets.

So, from an initial seed, you can derive

a large number of public-private key pairs.

And you can use those for all kinds of things.

If I have a wallet, I might want to receive money

with one address and send money with another.

I sometimes don't want to reuse my address.

And there's a number of reasons of why I might not want to do that,

one being privacy, another being security

and some elements of cryptography with non-swe use and whatnot.

But at the end of the day, the moral is,

with a simple seed, you can have a large number of private keys.

And that composed together is a cryptocurrency wallet.

There's software to help you do this.

And some of it is good.

Some of it is bad.

But today, I think most of it is just awkward for the regular user.

Another thing to note is,

in order to do this, you need randomness.

You need chaos from the universe.

You need to acquire that chaos somehow

and put it in your little bits and bytes

and package it in a safe, secure way.

And so, you know, cryptography needs this as a core primitive.

And if you don't have good randomness,

terrible things will happen, not to be too foreboding.

The problem is, computers are really bad at generating good randomness.

They're really great at following instructions.

They're really bad at doing random things.

They like to do what they're told.

You know, I don't know about new age quantum cryptography

or computers or whatnot. But, like, the computers I've been working with are pretty random.

Or not pretty random.

They're pretty just regular.

They do what you tell them, and that's what they do.

So there's a lot of reasons why you need randomness in your compute.

If you're making video games,

you want your characters to maybe start in random places.

If you're making API keys, maybe you want to,

you know, you don't want them to be predictable.

And so you need to have a good way to get random numbers.

There's good ways, and there's easy ways,

and there's these cryptographically secure ways to get random numbers.

They're used for different purposes.

Some are lightweight, fast, and don't require a lot of compute resources.

Others may take up more resources

but give you outputs that are not predictable

and don't reveal any of the inputs.

And so cryptographically secure PRNGs,

the pseudo-random number generators, are kind of the ideal in a lot of situations when you're dealing with generating keys for wallets.

So that's randomness.

And another thing to note is this is a talk about cryptocurrency,

but people use BIP39 mnemonic seed phrases to back up all kinds of things.

I don't know who here has heard of PGP.

Yeah, nice, nice, nice, nice.

So other places that would be like, what's that?

Well, it's pretty good privacy.

But there's ways to have, like, a 24-word mnemonic seed phrase

be used to derive PGP keys, which is pretty cool.

But anyways, the point there is, like, it's not just cryptocurrency.

Let's talk about the theft.

So I've never seen a bank get robbed

except in Hollywood movies.

And, oh, the slides aren't showing.

Did they just stop showing

or have they not been showing?

Okay, I'll do the good old plug it.

Okay.

Thanks for the call out.

So anyways, a theft.

Who's ever seen a robbery?

I haven't.

I hope you never have to.

But on Reddit, it kind of looks like this.

You just see someone, hey, my money's gone.

I think a bunch of other people's money's gone.

What happened?

And that's not where our journey started.

My journey started when I got a message from a friend

saying, hey, do you still have your Bitcoin?

I was like, what?

I don't know.

Let me go check.

So I have to go swim into my underwater cave,

feed the alligators, pop up, open the vault.

Yeah, it's still there.

Actually, it's not that hard.

You can just, if you know your addresses, you can just look.

But, yeah, my Bitcoin was there.

My money, you know, I don't know what money is,

but I like to think of Bitcoin as money that I like to use.

And I was like, dude, where's yours?

And they were like, it's not there anymore.

That sucks.

It's not, you know, you open your wallet and a dollar bill's there today.

And then tomorrow you look and it's not there.

You know, paper doesn't just evaporate.

Maybe it gets wet and disintegrates, but there's still remnants.

People put, like, ceramic disks in that stuff, you know.

And there's always a trace of where money went.

And on the blockchain, it's no different.

So, we saw that a bunch of money moved

and was consolidated.

And we knew two people in our social group.

You know, I don't have a lot of friends,

so this is like a large portion of my social network had been compromised.

And I was curious to understand how and why.

Maybe I'll never understand why, except for human greed.

But the how was very interesting for me,

because this is magic math,

and magic math is no different than regular math.

It just takes sometimes a little bit more for muggles like me to understand.

So, overall, we saw a 37-bitcoin move at this time.

And, you know, we saw that it wasn't just two people

that were in my friend's group.

We saw many other people.

So, a team forms, you know.

And we're not like the Avengers.

We don't have fancy suits.

I work in a garage in my house.

And other people work all over the world.

The good thing is we did have people

who knew how they generated their keys.

They knew how they stored them.

They knew the security models they were up against were...

They took precautions, let's say.

They weren't just downloading an app, running something on an online computer.

They were very tight about the attack surface

and generated keys and air-gapped machines

that had never touched the light of the internet,

running minimal Linux operating systems.

And so, it was very curious.

What we discovered in our research

was the common denominator was a software called LibBitcoin Explorer.

And so, you know, you try and understand how your well gets poisoned

and you look upstream

and, you know, or downstream.

We stand upon the shoulders of giants

and sometimes those giants just rot and die.

And in this case, we discovered some rot

and we decided to take a closer look at this software.

Now, LibBitcoin Explorer is kind of a random software.

And one of the questions some people were asking is, like,

well, how did these people even start using this software?

Well, they tried to do things by the book, literally.

The problem with dead trees is they don't get updated

as often as digital bits and bytes.

And what's true yesterday is not always true today.

So, when a book says something, generate a random seed

using operating system random number generator,

and your operating system is Linux, you feel like you have some guarantees

with a thousand eyes, all bugs are shallow,

or whatever that saying is.

Unfortunately, this turned out not to be true.

The bxseed command from LibBitcoin generates wallets

via the Mersenne Twister,

and it's not just a little dance here.

We're talking, like, you know, just numbers and stuff.

But numbers can dance, too, if you look at them right.

Some of them wiggle.

Some of them squirm.

And in this case, with this variant of Mersenne Twister,

this whole MT19937,

I'd be curious if anyone knows what that number is.

It's a prime number.

2 to the 119th.

Anyways, 32 bits of initial state

was all that was allowed in this implementation for generating random numbers.

Now, 32 bits seems like a number,

but it's not a very – it doesn't allow for a lot of possibility, possible outcomes.

And when we saw this, our heads kind of exploded

because we were expecting 256 bits of chaos and entropy

entering our little random number generator.

So, to not see that was a shock,

and definitely we felt like we were on the right track.

And so, you know, again, these numbers,

32 bits is a little over 4 billion.

And 128 bits is a little over 360 –

340 undecillion, I guess.

It's like 10 to the 36.

I don't know.

Undecillion is an interesting word.

In British English, it means something different.

And it also – yeah, anyways, look it up.

Undecillion.

But, yeah, so once an attacker knows your master key,

it's game over

because this whole key derivation stuff.

Like, once they know the initial state of how you derived all these other keys,

they can just walk down your path and check

and see if there's any cherries left over.

In this case, cherries are cryptocurrencies, you know, assets.

And so, theft is trivial.

With 32 bits, you can rent a cheap box at Hetzner.

You can have a gaming computer brute force this

in a matter of days, if not less.

And also, it's – this is not just Bitcoin.

People were using this, you know, for Ethereum,

a bunch of other cryptocurrencies,

and, yeah, it's – you know, maybe people were using it

for PGP, too.

I don't know.

But, anyways, we're talking about cryptocurrency here.

So, what did we do?

We saw an active exploit.

And by we, I mean the Milkside team.

We saw that this was happening in the wild.

We knew that this was – there was some entity

that was moving money,

and it wasn't the entity that was originally owning that money

or owning that currency.

So, with active exploits, we wanted to expedite

the disclosure process and inform the public

so they could have an informed decision what to do with their assets.

Now, you know, it's a social norm to do 90 days.

With Google Project Zero, they kind of set a standard for this

for, like, seven days if you see active in the wild.

And that's what we did.

We filed a CVE.

We did a detailed public write-out.

We reached the – you know, reached out to the maintainers of the software

and told them before we were doing this to have a coordinated disclosure.

They didn't see the world as we saw the world,

and that's okay.

But when people's money is on the line,

we had to make a choice,

and we decided to make the choice that made us sleep peacefully at night.

We wanted to tell the people to protect them.

And the name – I love the name Milk Sad.

I felt very sad when I learned about this,

and people didn't lose just, you know, their milk money.

They lost their savings.

They lost a belief in the rigidity

of a cryptocurrency system.

And that's a hard thing to build back.

When we first discovered that the initial state

was reproducible,

that we could generate the same mnemonic seed phrase

over and over again by setting some parameters

and depending supposedly on, like, system entropy

and getting the same mnemonic seed phrase,

we were kind of stunned.

And we realized, you know, kind of what the problem was,

everything else after that was just diving into the problem,

fully understanding it,

fully documenting it,

and preparing public disclosures for that.

We also, again, like, we were curious about how the attackers did this

and how big this problem was,

and was it just us using this software?

Or were there other softwares out there,

cryptocurrency wallet implementations that had similar issues?

Again, you don't need advanced degrees in cryptography.

You don't need specialized hardware to do what we did.

You just need to understand how these numbers work.

And once you understand initial PRNG seed states

for these systems,

you can simply enumerate over all the potential address space

that you want to spend time deriving

and checking if that address had ever been used on the blockchain.

And if so, you can see that address was vulnerable,

and that money was vulnerable,

and maybe it was stolen, maybe it wasn't.

But voila, you get answers to how much money

moved through these weak wallet systems.

This was a lot of time to dive through all the aftereffects

of this attack and exploit,

and we can still spend hours, days, months, years

diving into everything.

You can be your crypto sleuth like ZachXBT

and trace where all the money went.

We didn't do that.

You know, we didn't find all the answers to all the questions.

And, yeah, there's a lot of other coins out there,

cryptocurrencies that we could have looked at that we didn't.

Bitcoin, Ethereum, Doge, XRP,

these are all, like, cryptocurrencies,

and these are all systems that were affected by this compromise.

We're also not alone here.

There were other researchers that were working on this problem,

and from them we drew inspiration, and, in some ways, collaboration.

I don't know who here, any Drake fans here?

Okay, I feel sorry for the one person that raised their hand.

So, TrustWallet, not like us.

They didn't like the users in some ways.

They made some mistakes,

and not just one mistake.

They made multiple mistakes,

which is sad for the downstream users,

sad for the team that built this product and built a reputation around trust.

If I say, trust me, bro,

you're going to trust me, I'm sure.

Maybe, you know.

But probably not.

I'm just a stranger on the Internet most of the time.

And it's just, again, this is in the wild.

These weren't vulnerabilities we found.

These are just out there.

You can look them up.

And in this case, the PRNG was seeded with time,

which is really not a good idea.

Unix time starts in 1970,

and we're in 2024.

So, like, no matter what,

it's just not a lot of years to go through,

which is why I always set my clock 100 years in advance.

My plots are measured in centuries.

And just for this meme, you know, I don't know what Drake is all about.

He just is a super predictable person, though.

And he just doesn't like the good stuff.

He's just not like us.

So, we avoid him.

We try not to be like him.

I'm sorry if he's your idol.

This is my opinion.

I'm not speaking on behalf of the Milksed research team or anyone else here.

And if I offend you, I apologize.

I just like to be honest with myself and the audience.

But, yeah, what the highlights, you know?

We're done with Drake.

There were nine wallets that we discovered

with lots of money.

So, in cryptocurrency land, they call them whales.

And these whales had quite the dork of a wallet.

67,000-plus bitcoins.

Went through these wallets.

At the time, that's about a billion dollars.

At 20,000 U.S. dollars per Bitcoin.

Today, that's five times as much.

I think Bitcoin hovers around $100,000.

In my world, one Bitcoin will always equal one Bitcoin.

And everything else is everything else.

But, again, this shows you that it wasn't just retail,

random people reading books.

This was people who were spending a lot of time and energy,

had a lot of assets involved and vulnerable,

which was quite impressive and surprising.

We don't know what happened with this money.

We don't know if these people or entities

that had control of these wallets moved them safely.

We kind of assumed they did.

We don't know if they knew what was happening here in 2020.

Mind you, we discovered this issue in 2023.

So, it was three years later.

But, yeah, just kind of crazy.

That's a lot of money to just float around the Internet and be able to be grabbed.

Cake.

I like cake.

I hate when my cake has poison in it or razor blades.

If you ever eat an apple on Halloween, be careful.

Check it twice.

Some people are naughty.

Some people are nice.

And, in this case, Cake Wallet was not so nice.

You know, a lot of programming languages have, like, random SDKs.

It's just easy native library implementations where you can get randomness.

And, a lot of them don't have secure, cryptographically secure randomness

by default, which I find really awkward.

I think that's something we should talk about here.

Like, why don't we provide safe defaults

for all the programming languages as, you know, a primitive?

So, something to think about if you're developing languages.

Default to safety first, please.

And, yeah, we knew that this was insecure,

but a lot of people didn't know how or, you know, how to derive these addresses.

And, luckily, lead researcher Christian,

our knight in shining armor,

saw the puzzle and decided he needed to break it.

You know, he was kind of nerd-sniped by this.

And, a lot of us were not spending as much time

diving into Cake Wallet because we already were moving on to things.

But, the fixation Christian, you know, spent was well worth it.

He discovered that they weren't using 32 bits of seeding

when you expected 128 or 256.

They were actually using 20 bits.

You know, and 20 bits means I can almost do the calculations with my hands and toes.

But, I lost a lot of touch in my pinky toes

due to frostbite.

So, it would be difficult for me, but if you are talented

with all your digits, you can show me how to calculate stuff with them.

That would be super cool to do by nay.

But, 20 bits is not a lot.

So, easy to brute force.

And, Cake Wallet is a software product that a lot of people use.

It's great.

It has... It's not great.

I don't know.

I shouldn't say that.

It is what it is.

But, the cool thing about it is you can reach out to the users,

unlike open source projects, which is a little bit harder.

You know, you can send out something to the mailing list or not.

So, our team, Christian, reached out to Cake Wallet people,

and they're like, yeah, we'll throw a notification up,

and we'll tell people.

The problem is, people don't update their software.

They didn't get the notification.

They probably just set it and forget it, you know.

And, we waited six months

until we disclosed this issue.

Six months of just sitting there, hoping things were going to be good.

Two days after disclosure, the remaining funds

in those vulnerable wallets were removed.

We suspect they were removed by not the originators of those funds.

Sad times.

Sad times. Sad times.

So, back to our team and what we were up to.

There was a lot of debate, a lot of turmoil.

I would say, you know, I trust everyone that I worked with,

and you had to.

Because, when there's a big bag of money on the ground,

and anyone can just pull up and pick it up,

anyone in our team could have done this.

Anyone in the world who knew about this

could have done this, who reviewed the open source software.

And, you know, what do you do with that?

As a good Samaritan, you see

a 100-year-old note or something on the ground.

You might take it to the police station and say, hey, I found this money.

I don't know who it belongs to, but I'm sure they need it.

They want it.

But, in cryptocurrency land, how do you verify,

like, that indeed was the person that, you know,

how does anyone verify that that's their 100-year-old note?

It's kind of tricky.

Maybe there's CCTVs in the area.

You can see someone slip, you know, slip their glove,

and a dollar falls out or whatever.

But, in cryptocurrency land, it can be quite difficult.

And there's a lot of legal and tax implications.

And we come from many jurisdictions,

from Canada, the U.S., Germany.

I don't know where all our research team comes from,

but we definitely debated this, and it was a hot topic.

Another hot topic was, do we open source the code that we use to derive these addresses?

Do we share it with the world?

We're proud of the work we did.

We spent a lot of hours.

We spent a lot of time working together,

making sure we understood the scope of some of these issues.

And we didn't get unanimous consent

to release all the source code.

We had a lot of disagreements.

There's some people who live and die

by the open source sword in our social group, in our research team.

And to them, it was a tragedy to not share this with the commons.

And then there was others who just don't want to give people

who don't want to spend the time understanding the situation,

even if they have bad intent, easy resources to do this for cryptocurrencies

and extend it to other potential networks

that might not have been compromised in the initial attack.

So, again, it was a tricky situation.

We wanted to share some things with the public.

We didn't want to share everything with the public.

We did allow people to look up to see

if they had compromised mnemonic seed phrases.

You could go to a website, provide a SHA-256 hash

of the seed phrase, and check to see

if it was in our database.

Obviously, that was even discussed internally,

because what if people put their entire seed phrase in there and then blame us for being compromised?

And that is a tricky, sticky situation.

But we did want to provide some type of public service

for people to check before they swept their funds.

But, yeah, some numbers,

lots of money through this.

This isn't money that was necessarily stolen.

This, and by money, I just mean Bitcoin,

or, you know, that's what we're looking at here.

But these are Bitcoins that move through compromised wallets that could have been stolen at any point in time.

And I just find that fascinating.

This is world-changing money.

This can fund your nuclear arsenal.

This can buy you many islands

or politicians or Twitters or whatever.

Actually, maybe not Twitters.

I don't know.

It depends on the price.

But, yeah, this is a lot.

And it was crazy to see so much of this asset

go through weak systems.

It just felt weird.

What can you do?

That's a good question.

As a developer, how can you protect yourself?

How can you protect the people you're building software for?

A lot of us are building software for people.

Sometimes people are building software for, like, robots

and stuff and non-peoples.

But that's also great.

You should still protect those entities as well.

Question everything.

My mom always told me to question authority.

And I carry that with me everywhere I go.

I really doubt everything I see.

And really have to strive for understanding

to feel confident and comfortable

to use technology that I would use in a secure system.

And when I'm building software, I always like to check it twice.

I like to get it externally audited.

And, you know, when you're using randomness,

make sure you're not just doing silly mistakes.

And this is a question of how we get people

to break this cycle of repeating the same mistake over and over again.

So, as the average user, if you entrust your money to software,

if you entrust critical things like your privacy to software systems,

demand security audits, you know, request them,

demand them, pay for them.

Do what you can to help the systems

keep your stack updated.

So, again, this is not a full enumeration.

These are just useful, you know, things I find useful.

One thing to note with the BIP39 setup mnemonic seed phrase

is if people added a password, which is part of the BIP39 spec,

a passphrase, to their setup, they probably wouldn't have been compromised

in the initial attack.

People, the attackers would have had to try and crack the password

in order to then enumerate all of the downstream addresses.

So, that was something interesting about this particular incident

is some people were protected just by adding that simple passphrase.

But, yeah, open source is great,

but it doesn't guarantee safety, as we all know.

In conclusion, chaos is required for some things

in compute and in life, as we know in the Chaos Congress.

There's often good chaos everywhere,

and you try to avoid the bad chaos.

Be careful.

It is used everywhere in passwords, session tokens, all this stuff.

Try not to let it happen to you.

Try to understand and do your research

and do what you can to build confidence in the technology you're using,

and that's for everything.

Where do we go from here?

Well, we spent a lot of work proving over 20,000 weak wallets

existed in the cryptocurrency space.

A lot of us have full-time jobs, families,

mouths to feed, breaks to take, you know, sleep.

And so, we're doing a bunch of other things,

but we're still very interested in this area,

and there's a lot of research and investigations that can still happen here.

So, we're constantly pushing out updates,

and by we, I typically mean Christian, but the lead researcher.

If you have anything interesting or, you know, comments or feedback

or you want to learn more,

always feel free to reach out to us.

And we're hosting a longer Q&A session

with the research team.

You know, I'm just a puppet here being pulled by the slides,

but if you want to meet more of us, please do so.

We'll be in Sol 6, which is, I think, a floor below us,

and love to see your faces,

love to talk to you about this problem

and find solutions that can really break the cycle

of bad entropy in good intended systems.

Also, shout-out to Mo at Millieways.

These slides and the template come from him,

and originally that was derived from the 38C3 design team,

and I just love the design.

So, thank you very much, everyone, for coming here

to listen to this talk,

and I'd love to field your questions for what I can answer

and for anything I can't,

I will just shepherd you downstairs to Sol 6.

John Nolte and the Milk Set team, thanks a lot for this research,

thanks a lot for the presentation,

thanks a lot for the disclosure.

Anybody coming up with questions?

I see some questions here.

However, hold on for a second.

We want to have a look at the internet.

Are there online questions?

Yeah, please.

The first question from the internet would be,

were all wallets using Mercy and Twister

to generate the seed at that point?

If not, how did the hackers identify the ones which did use it?

So, I don't know how the hackers identified the weak wallets in their systems,

but the answer to the first question is no.

They weren't all using Mercy and Twister.

You can look at the other implementations in our write-ups,

but yeah, there was a few implementations

and issues there.

Is there anything else from the internet?

Yes, we have one more.

The question is if this flaw is still out in the wild,

especially for non-Bitcoin cryptocurrencies.

Is the flaw still out in the wild?

Yeah, the software, you know,

once you publish the software version,

it's there forever, most of the time.

You know, there's people who archive all kinds of things,

so most things on the internet don't die.

What's dead can never die.

And as far as active exploits,

if you put money in one of these compromised wallets,

it'd be a fun game to see how fast it moves

by not your hands, not your system.

I assume now there's just people who are listening

or systems that are listening,

waiting for money to enter a weak wallet

and snatching that money immediately.

A fun game to play would be to see

if they pay more gas than the money's worth.

If they're sophisticated, they'll check that first.

If they're unsophisticated, they won't.

But yeah, it's definitely still active.

There's still these issues.

And there's, you know, systems that we haven't identified yet.

So that's still up in the open.

Okay, for everybody else in the room,

just line up at the microphones.

Therefore, microphone number three, please.

Thank you.

Great talk.

I would like to know whether this applies to Monero as well.

And have you looked into Microsoft Research Z3?

Answering second question first, I haven't.

I'd love to know what that is.

And so I'll mentally note that down,

but probably forget it.

So I'll try and write it down later.

But it's recorded.

So I'll just actually I'll just watch the recording.

But yeah, as far as Monero and other cryptocurrencies are compromised,

it's outside of the realm of cryptocurrencies.

It's more in the realm of the cryptographic implementation for the wallet is flawed.

And people were using these mnemonic seed phrases for all kinds of things, not just Bitcoin, not just Ethereum.

I don't know if we we didn't do any research in Monero.

So that's an interesting field for privacy coins.

I think we did see Zcash.

Not everyone like makes Zcash private, I guess.

So but but yeah, I would assume Monero

Monero wallets would be compromised

if they generated their their seeds with this software stack.

OK, thank you.

Thank you.

And again, microphone number three, please.

So using a non cryptographically secure pseudonym PRNG,

it's kind of a basic pentest finding.

At least that's what my experience in my professional deformation, I guess.

So I would be kind of scared when I see it

in software like like this, that's supposed to be all that that's supposed to be developed by competent developers.

Have people considered this to be a supply supply chain attack on the ecosystem?

I mean, a compromised supply chain, that's what happened here.

So, yeah, like the well was poisoned.

People trusted software and they stood upon the shoulders of giants

and they realized those giants didn't have a strong foundation

and everything they had kind of crumpled into dust.

So 110% supply chain problem,

definitely recommend having supply chain security solutions

to, you know, mitigate against this.

And that's where a lot of code review comes in.

But yeah, it was mostly like code review probably would have caught this.

It wasn't a fancy thing like no one compromised the build server

and there was a build release artifact published

that was at issue.

But the source code was clean, like SolarWinds or whatnot.

So, yeah, it was just bad code put into the system.

Flawed, I guess, code.

Maybe the, I don't know.

Yeah.

Okay.

Yeah, it's fair that I'm not that paranoid about it.

But yeah, shit happens.

Definitely be paranoid.

Every pull request is a potential input for compromise.

So, constant vigilance.

That's one of my favorite Harry Potter characters.

Mad-Eye Moody would say.

He was compromised.

Anyways, yeah, by a supply chain attack.

But yeah, cool.

Any other questions?

No, thanks.

Well, in here, microphones are empty.

What about the internet?

Some more questions from there?

No.

Anybody interested in anything particular here from John?

No?

Well, then, let's thank John again for this.

*clap*

♪ (38C3 outro) ♪

[Translated by Pekka P]

(KYBS2004 course assignment at JYU.FI)