Real-world useful application for Bitcoin: Malware/Hacker Canary

[casascius]

I have thought of a very real practical use for Bitcoin, in fact it has come from the subconscious.  And it comes out as a valuable side effect from one of Bitcoin's greatest criticisms: the way they can be anonymously and permanently stolen.

tl;dr: The application: detecting if your machine has been hacked, even if antivirus catches nothing.

Whenever I use computers, I always assume they are "dirty" unless they have been mine all the way from the day the operating system was installed and I haven't allowed anybody to use it.  And even then, I still am suspicious of my own machines.  Of course, by "dirty" I mean they may be logging my passwords and activity, and/or giving someone remote access to my files.

And a "canary" is a reference to a canary in a coal mine - the sacrificial bird that dies first if the air goes sour, its death serving as a warning to the miners to get themselves out before they too succumb.

One thing I find comforting is when I load a small number of bitcoins on a machine connected to the internet, and observe that the bitcoins are not being stolen.  Or if I leave small change on a machine overnight, and find it still there in the morning (a pretty rare occurrence since I use paper wallets religiously, but there are occasions where something like 8.7 BTC is the change from a transaction, which just isn't enough for me to break out a paper wallet if I am in a hurry or whatever).

OK, I realize that it's not necessarily perfect: if someone has owned my machine and considers me a high-value target, or is after me specifically for something, they probably aren't going to tip me off by stealing my bitcoins if I potentially have something worth more to them on my network or machine.

But for the average target being attacked by the average bitcoin-aware attacker spreading general-purpose malware that, among other things, steals bitcoins - then leaving a few bitcoins there as a sentinel to see if they get stolen would probably be a FANTASTIC check against a useful percentage of typical malware and hackings that antivirus fails to catch.

All one need do is store the bitcoins on their hard drive in somewhere relatively easy to find (e.g. wallet.dat in the default location), and have a third-party service watching those coins on the block chain to see if they move.  The service could e-mail and text me if the coins suddenly move.  I would treat it as a sign that I need to unplug from the internet, back up and reformat my machine ASAP.

Nothing is certain, and that includes the ability of antivirus software to detect malware... but if I am on a machine I consider highly valuable, leaving bait of fifty dollars worth of bitcoins might be one of the best supplementary antivirus measures money can buy.  Best of all, if I never need it, it costs me nothing, and it hopefully it appreciates and pays dividends over time.  If my $50 antivirus appreciates to $400 and I still only need $50 worth of "hacker bait", that's still $350 I could pull out for free.  Yet if it depreciates, the loss of utility is minimal: it'll probably be stolen at $10 nearly as likely as at $50.

If I am just trying to protect myself against run-of-the-mill malware or a machine with nothing interesting on it, then even 1 BTC is plenty.

Same thing goes as reward money for hacking, say, an SQL server, to see if anyone has SQL injected their way in.  If I were to leave $1000 as bait in one of the tables of a database server, it would probably be tempting enough for the first hacker to want to monetize, especially if he thought someone else would find it soon if he didn't swipe it himself.  If a hacker breaks into a database, 1 BTC is probably not going to be worth blowing his cover for, but unless the hacker is certain that the data on that server is far more valuable - $1000 USD almost certainly will be overwhelmingly tempting.  And although I can't be absolutely sure of anything, seeing that $1000 not get stolen would be an anxiety reducer as long as it remained if I'm a sys admin.

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[pointbiz]

+1

I agree with your line of thinking. It's also how you can tell a paper wallet was not caught by malware. Send the paper wallet 1 BTC then wait a while. If it's not stolen then the probability it's safe goes up and you can send it more BTC.

Leave 0.01 BTC on your Android Wallet... I'm doing that. A malware app would steal that in a heartbeat.

BTC the natural anti-virus alert...

[pointbiz]

I just thought again about your bitcoin address and private key in the SQL db. Maybe in a table called 'Bitcoin'... stroke of brilliance!

[westkybitcoins]

Yep. I've already been doing it with a small wallet. So far, no thefts....

[cypherdoc]

thats really funny. 

i've been subconsciously doing that all along.  as we speak, i have about 16 BTC intentionally left on my laptop waiting for it to be stolen.

i just never thought about commercializing it.  how many computers and servers exist in the world today?

[dunand]

Not a bad idea. It reminded me something. Some people leave some change around the house to see if the babysitter will take it.

[casascius]

If this idea gets taken seriously, this would organically increase the utility and the demand for Bitcoin a lot.

[bitplane]

This is a really cool idea. User pays $10 for $5 worth of BTC, they get an installer that creates a wallet.dat in their user profile, they enter their email address and vault address, they get an email alert when the money moves.

This could be a viable and completely automated business, I hope someone makes it.

[istar]

I like your thinking, however it could get you into a false feel of safty.
The hacker would wait for you to use a wallet with much greater amount on.

Would be even better if those stolen coins would not really move, they would only show an attempt to move them has been done or if they could be tracked down or the hacker could be tracked in someway. Perhaps that will be possible with the new client.

[TTBit]

This is similar to the 100 btc bounty I put up for a compromised casascius coin: https://bitcointalk.org/index.php?topic=52004.0

If an attack were to happen, there would be an incentive to publish the breach for 100 btc, users would stop accepting coins as payment, and owners of the coins would immediately redeem.

Question: How can this concept be expanded to know if someone is reading my email, or has logged into my bank account?

[deepceleron]

/*begin advanced wallet-stealer metacode*/
FileScan [(filename:*.bat); (filename:*.cmd); (starts: #!/bin/bash)]
 if BinScan (FileScan.Results): (string "--datadir" DirName)
  send (filesIn DirName where filesize < 10mb) to (backdoor)
 if BinScan (DirName/*): !"KeyA"
 install Bitcoin (encryption key keylogger version)
If (bitcoin.wallet.default.balance) < paltrysum
 leaveAlone

[casascius]

Question: How can this concept be expanded to know if someone is reading my email, or has logged into my bank account?

It probably wouldn't work.

If it looks like obvious bait, the mice aren't going to take it.

But if the mice are automated and programmed to smash and grab everything they see upon arrival, that's where it's going to work.  Example, you get malware that, upon installation, steals your passwords and bitcoins, and then proceeds to spy on you, or allows the attacker to run new payloads on your machine.

Depending on how many machines the attacker is infecting, the attacker might not have time to deeply scour your machine for more interesting stuff.  Maybe he will, maybe he won't.  And perhaps whatever you find interesting/important is not of value to your attacker.  The possibility he will take your bitcoins is decent enough, though, that there is really no harm in leaving them there.

I am not sure it leads to a false sense of security.  It is a heuristic, nothing more.  Antivirus software is the biggest offender when it comes to a false sense of security, someone thinking about baiting hackers with bitcoins has thought about this a little more.  No measure could possibly rule out an intrusion (short of staying offline), but it's also possible to employ reasoning and common sense.  

According to a speech given at a recent DefCon by a self-proclaimed malware author who claimed to have switched teams, these malware authors and the websites that trick users into getting infected receive as little as pennies per machine they infect.  Imagine that - you paid hundreds or thousands of dollars for your machine, and someone is willing to ruin it for under a dollar.  It is only worthwhile, presumably, because they are infecting machines in bulk.

Meanwhile, bitcoin-mining malware is proliferating.  An infection by such malware, too, is worth only pennies to whoever infected you.

If many machines are getting infected because the perps are willing to do it for small change, surely these same people wouldn't hesitate to swipe five or ten dollars from you.  Surely a lot of them must lack the time and/or sophistication to go mining on your machine for files that may or may not be interesting to them, especially if you don't have software on your machine that signals something they want (e.g. POS software suggesting you're a cash register and have credit card numbers)... and may very well be more than satisfied with several instant dollars.

[cypherdoc]

its almost like the carrot vs. stick approach.  many ppl believe its easier to get ppl to do something by offering them something of value. 

in this case i agree that most malware attackers would be more interested in getting whatever they can for the least amount of risk, ie, taking the btc's.  i think the temptation would be too great.  and as casascius said, most of this malware is automated anyways and won't discriminate.

as an aside, i think the obvious needs to be said:  you can't store USD's on your computer to accomplish the same thing.  they exist only in a bank, in physical form, or within a credit card # which really isn't the same thing.

[Zotia]

Is it possible to make a wallet that looks like it has money, but doesn't?  That would allow you to have a really good bait (such as thousands of BTC) without any risk.


For example:
-Make a fake wallet that has the public key of someone who is rich, but an invalid private key.
-Make a real wallet.  Modify the blockchain on your own computer to look like your wallet has money.
-Make a new (real) wallet.   Send real money to it.  Keep a copy of the blockchain once it gets the money.  Send the money to your real wallet.  Delete your blockchain data and use the data you backed up.  Don't let the blockchain be updated.


(Note: In all of these cases, you are using a "fake bitcoin client". If you want to actually use bitcoin, being able to use a "real bitcoin client" with a "fake bitcoin client" on the same computer is a problem that would need to be overcome).


Would any of these ideas be possible to do?

Would any of these ideas cause more work for the virus writer than for the anti-virus writer?

[casascius]

Is it possible to make a wallet that looks like it has money, but doesn't?  That would allow you to have a really good bait (such as thousands of BTC) without any risk.

For example:
-Make a fake wallet that has the public key of someone who is rich, but an invalid private key.

The event you're looking for is the theft of the money being published to the block chain, which you can't detect if you don't let happen.

Now if you want to secure multiple machines, you could skimp a bit so that some of the bitcoins are shared across the machines.  Suppose you have 10 servers and you want to put 1000 BTC bait on all ten, but still want to know which machine got stolen from if it it disappears.  You could generate 10 wallets, send one BTC to each of them, and then import a single private key worth 999 BTC into all the wallets (the same key into each wallet).  All of the wallets will appear to contain 1000 BTC, but 999 of it could only be stolen once, and then you would know which machine(s) got hit by looking at which wallet(s) had their 1 BTC stolen with it.

-Make a real wallet.  Modify the blockchain on your own computer to look like your wallet has money.
-Make a new (real) wallet.   Send real money to it.  Keep a copy of the blockchain once it gets the money.  Send the money to your real wallet.  Delete your blockchain data and use the data you backed up.  Don't let the blockchain be updated.

A hacker isn't going to be concerned with your copy of bitcoin or the blockchain (unless he is remote controlling your computer and feels the easiest way to steal your coins is to just use your copy of bitcoin to send himself the transaction).  Far more likely, it's going to be you accidentally installing malware (e.g. via a trojan or a drive-by download) that just swipes the wallet file and sends it to the attacker.  The block chain file is too big for the malware to send, and is full of public information anyway, there's no reason to steal that.

[cypherdoc]

Is it possible to make a wallet that looks like it has money, but doesn't?  That would allow you to have a really good bait (such as thousands of BTC) without any risk.

Yes, but it would serve no purpose.  The event you're looking for is the theft of the money being published to the block chain, which you can't detect if you don't let happen.

Now if you want to secure multiple machines, you could skimp a bit so that some of the bitcoins are shared across the machines.  Suppose you have 10 servers and you want to put 1000 BTC bait on all ten, but still want to know which machine got stolen from if it it disappears.  You could generate 10 wallets, send one BTC to each of them, and then import a single private key worth 999 BTC into all the wallets (the same key into each wallet).  All of the wallets will appear to contain 1000 BTC, but 999 of it could only be stolen once, and then you would know which machine(s) got hit by looking at which wallet(s) had their 1 BTC stolen with it.

but that wouldn't work so well b/c you are trying to protect all 10 servers at the same time.  once one server gets hacked, the protection on the other 9 gets stripped away leaving them exposed.  this is assuming that the MW is looking to steal other data besides just BTC's.

[casascius]

but that wouldn't work so well b/c you are trying to protect all 10 servers at the same time.  once one server gets hacked, the protection on the other 9 gets stripped away leaving them exposed.  this is assuming that the MW is looking to steal other data besides just BTC's.

The other nine servers will still have 1 BTC up for grabs, and you'll still know which server got hacked by seeing which of the ten 1BTC wallets got stolen.  At that point, if you want to throw more BTC into known shark-infested waters to make sure all the servers have a treat, you can bet they will probably get eaten, and it won't tell you much more than you already know.

Exposed is a misnomer - once the hacker is in, they're exposed whether the servers have BTC or not.  But now you know you've been hacked, which is 95% of the battle.

[ptshamrock]

what about creating an alternate blockchain with the same properties as btc ? Securitycoins

so you always can have a fake wallet there which is loaded with SecurityCoins but that is not visible to the intruder..
You still can check the movement of coins in the alternate blockchain..
you yourself know which is the real one and which is the bait.,.but the attacker can only find out by trying to move the money to his btc account..while he moves it in the worthless fakechain..


you get my thinking? sorry i am a bit unconctrated today to formulate my thoughts..mayb it was already considered..

[casascius]

what about creating an alternate blockchain with the same properties as btc ? Securitycoins

so you always can have a fake wallet there which is loaded with SecurityCoins but that is not visible to the intruder..
You still can check the movement of coins in the alternate blockchain..
you yourself know which is the real one and which is the bait.,.but the attacker can only find out by trying to move the money to his btc account..while he moves it in the worthless fakechain..

It would not work.  Coins from alt chains are not bitcoins.  The thief can't sell them as Bitcoins.  The Bitcoin network won't accept a transaction on them, nor recognize them as having any value.  From Bitcoin's perspective, they are functionally identical to a wallet with 0 bitcoins.

[cypherdoc]

but that wouldn't work so well b/c you are trying to protect all 10 servers at the same time.  once one server gets hacked, the protection on the other 9 gets stripped away leaving them exposed.  this is assuming that the MW is looking to steal other data besides just BTC's.

The other nine servers will still have 1 BTC up for grabs, and you'll still know which server got hacked by seeing which of the ten 1BTC wallets got stolen.  At that point, if you want to throw more BTC into known shark-infested waters to make sure all the servers have a treat, you can bet they will probably get eaten, and it won't tell you much more than you already know.

Exposed is a misnomer - once the hacker is in, they're exposed whether the servers have BTC or not.  But now you know you've been hacked, which is 95% of the battle.

assuming that the hacker will "accept" a mere 1BTC.  your reason for putting up 1000BTC to begin with implies that he wouldn't.