Bitcoin Forum

It's been connected to the internet, if I turn the internet off, is there a way my BTC can be stolen without physically taking my pc?

No but if you have keylogger or malwares in your PC, there is a chance that your Bitcoins can be stolen once you connect to internet.

I think no
but someone can physically take your bitcoins either taking you wallet.dat file, or exporting private keys or other way

That's good then.

depends. where do you store your bitcoins? if it's on blockchain.info for example your coins are not safe, since it's an online wallet.

if you use electrum, bitcoin core or multibit - your coins are always safe. as safe as your local machine & passwords :)

Bitcoin armory, and electrum

Only using old fashioned things like CDs or DVDs or flash drives!

Are you still connected to a network? If another computer or device on your network is connected to the internet, you could still be vulnerable, though far less so than the most of us.

Why don't you just keep the wallet file offline instead? No point just having a laptop not being used just to keep your coins safe when you can just store them on a flash drive or cd.

Bitcoin transactions can only be started using your private key. If you have the private key, you can transfer bitcoins from one address to another. It doesn't matter if your internet is on or off, if you have the private key you can even move bitcoins without having direct access to the internet.  :)

Your bitcoins are literally on the blockchain. Your computer has the private key to move them. Recently someone posted a good analogy:

Imagine there are a group of lockers in a public place. Each locker has the following:

    A lock that requires a key
    A window to see inside
    A slot that money can be put in
    An identifying number


Thefts happend because of these reasons:

    Keylogger / Virus / Spyware from plugin, altcoin etc
    Sending to a website (bitcoin transactions are not reversable)
    Sending to a scammer (fake payment sites and fake investment sites)
    Leaking of private key
    Hacked exchange
    Hacked online bitcoin wallet
    

I recommend using a sd, cd, paper wallet or hardware wallet. A computer has so muchsoftware running on it that every program you install either knowingly or unknowingly could be dangerous.

They cannot do that if you encrypt your wallet.dat file.

My suggestion is a few USB's or paper wallets.  Either one works great as cold storage.  Just make sure they are stored in safe places.

I think having more then 1 is a big thing.  If you have one usb and it gets corrupted, you are out of luck most likely.

So stay with cold storage, have multiple, and you are on your way to a safe wallet.

no man..your btc will be safe if no one has physical access except you , provided you are offline ..
if any key logger is installed and you are offline no man can hack your stuffs but the scene can be different if key logger is installed and you gonna be online..

so better be offline and don't let anyone touch your pc..

if your pc is clean being connected or not will not make any difference, if you knwo that your pc is infected(usually something wrong happen in this case, like cpu usage too high, strange filename ecc...) then it is better to move your wallet in another storage(offline is better)

my point is that you can have a online safe computer, in my case i have a wallet that it is always online with some btc, no one has stole those bitcoin from my desktop ever, they are still here

it is just a matter of dealing well with security

[1]Yes it makes a difference. If your PC is disconnected a hacker can't gain access to it. While it is connected, he can. There are infections that can't be detected by anything, not by the average person nor software because of its complexity. However, a security researcher (or a group) might.
I'm going to assume that you haven't heard about The Mask (a.k.a. Careto); you should look into it. Luckily AV's can detect it now, however there are probably a lot of these out there (e.g. finfisher).
[2] If nobody has stolen your coins, that doesn't mean that they won't. Depending on your balance you might not be a likely target. We've seen a lot of people (over time) ask for help on the forums because their wallets were compromised.

I wouldn't use USB's. They are have quite huge vulnerabilities and are prone to failure.


I'd recommend paper wallets as well. If you really wanted to store your Bitcoins for a longer period of time I would suggest the following:
1) Buy a type of stone (e.g. marble)
2) Get your private key and engrave it into the stone(It would be risky to let someone else engrave it; if he's familiar with Bitcoin he could steal your funds)
3) Place the stone somewhere and cover it (I have a few ideas) or bury it
4) Download D-BAN: http://www.dban.org/
5) Overwrite your HDD 35 times
6) Put HDD in a Microwave
7) If you have the proper tools, melt the HDD

The last 3 steps might be exaggerating (7 overwrites should be fine) but this is how I would stash my (potential) billions. Just make sure whatever you do, you make backups.

Read this topic if you want to secure your coins.
https://bitcointalk.org/index.php?topic=871213.0 (https://bitcointalk.org/index.php?topic=871213.0)

if my balance is still here(about 5 btc), this only mean that my pc is safe, and not infected, it's impossible that i have a wallet stealer, and still i have all my coins here, it does not make sense at all...

same thing for a keylogger or any other virus, none of the forum that i usually visit are compromised, my bank acount is also safe, this can only mean that my pc is 100% secure

just don't download trash(only signed file) and you're safe even online, hackers cannot connect to your pc magically, they need rootkit/rat ecc...so it is actually you that allow him to connect by installing those garbage



ah great now, plenty of newbie scammer are sending me pm , they want to try to scam those 5 btc i presume

It is actually recommended that you store your BTC on a computer that is offline most of the time.   A lot of us have cheap laptops that have a bitcoin wallet on them that are not connected to the internet.   It is much safer.

You can also use cheap old android cellphone to store your coins. You can turn on wifi or data packet,
only when you need to send or receive btc.

That largely depends on whether or not your system was already compromised when you decide to shut her down.  Shutting the computer down that contains your bitcoin wallet and coins won't save you boo if some unscrupulous hacker has already managed to get his hands on a copy of your private key.

No. Making such conclusions is wrong. You could be infected by a sleeping type of malware. Besides, I never said that you were hacked. I said that you weren't a likely target because of your low balance.
This isn't that true either. If they know your IP address then you might also be in trouble. Gaining your IP address isn't even hard. If you use Skype, they already know it.

my ip is dynamic, i'm not worried about that, being a target or not, they still need to find a way to infect me, which mean that they need that i download something or click on something, almost impossible

i think if you are really careful and know what your are doing, you are the best antivirus of your desktop, but i agree that such thing isn't advisable, average joe don't have the patience for something like this, they can not manage their own security

if there is a trojan or a keylogger in your pc, of course they will steal your data.
so even if your pc was off if they have you private key, decrypted. they can stole your money.
but if it's encrypted it will not stop them but just delay them.
and the most of trojans or keyloggers cannot be detectd by the most AVs (i'm got some victims of my keylogger the detection of AVs ar just 3 anti-viruss that detect it)
and the most of hackers or data stollers just stole passwords (especially paypal , banks) and credit cards numbers but i don't think about bitcoin private keys.

the important thing to remember is to keep the pc that has your wallet on, offline and never connect it to internet.
what i like to do, in order to secure my coins is to create an offline electrum wallet.
here a step by step guide that i bookmarked some time ago:
https://bitcointalk.org/index.php?topic=853288.0

well you need more than one antivirus, for example you can malwarebytes, also the free version of av isn't the same as the full version

anyway strong virus(like those that can hides themselves in any folder) are not a thing of everyday, it isn't that easy to be infected by those

Sorry, you think that you've got it figured out, but you don't. Opening a single email could be the ticket to your Bitcoin hell.

No. Having multiple antivirus software is a bad idea because they will counteract each other. They will start fighting over viruses, they will try to kill each other and sap your power. However, it is okay to have an AV and Malwarebytes.
Strong viruses aren't a thing of that you would encounter everyday, correct. However, this goes only for your average internet users.

You know that you can get your money back from Paypal or a bank? Good luck getting someone to send your Bitcoins back.

yeah i know, but i'm very careful everytime i open one, usually you need to download something there, also


it's funny how you always want to contradict me  :D, but you are wrong on malwarebyte, it can be used without any problem, along with others antivirus

to be even more safe you can buy a hardware-wallet:

https://bitcointalk.org/index.php?topic=899253.0

the thing that i wanna say that if anyone has physical access to your pc/laptop then the scene can be different..
its better to keep your wallet in offline in some portable hard drives.

or you can write your private keys in some place that no one would expect to find them, so they would not be subject to hardware failures

yes transferring your private keys to another place will be the best idea..or you can store all your coins to deep freezer...

it is better to sweep all your addresses into a new address that you create with your new wallet.
every wallet has this option to sweep addresses when you import, which means you send your coins to the new wallet instead of risking contaminating the new wallet.

That's good for you. Keep at it.

No. You're the one trying to be right all the time with false assumption, understanding and posting without backing up your words with facts/evidence.
How about actually reading my post before replying to me (hence the thread in meta)?

You should take this advice. Every time I've tried to move to a new wallet, I actually transfer everything to a single address (newly generated).

Another good option if you're willing to spend some money:

if you have 0.0001 btc of course your safe cause no one will work hard to stole your money.
but if it's 5 BTC even if your ip is dynamic or you have a cisco guard firewall. or DDos protection system or anything else.
the problem is your post,  this post got 500 views maybe anyone will try to get your ip address.
if a hacker know that he will get 5 BTC (1100$). you know!!

those 5 btc are here since bitcoin was 1000(so there isn't even the excuse of "you are just not a good target", hacker has stole a much lower amount than that), and none has ever stole them, like i said they can't simply attack your desktop without your "permission"

i agree. of all the "my bitcoin was stolen" stories that i have heard so far, almost all of them was the person's fault. like clicking on a phishing email, opening a suspicious link like fake blockchain.info address, having keylogger, using Tor,...
all of these can be prevented by taking necessary precautions. like having a good and up to date antivirus or using offline wallets,...

It is not hard for a malware to get into your computer without your permission.


Don't compare Blockchain.info. Bitcoins lost through Blockchain.info is very big and no, many of them were *not* due to users' faults.

depends on where u are storing your btc, if its on a pc - wallet , it will be safe as long as u reconnect ur pc, otherwise I Suggest u use an online wallet to store your cash and email encrypt it for extra protection! now days can even get mobile verification

I think you meant "safe as long as u don't reconnect ur pc". It can be safe even if he connects internet as long as he knows how to secure his computer from malware.


Storing Bitcoins on an online wallet is worse than storing it in a local wallet.

i have seen a thing that is "NSA put virus to harddisks for reaching it from far away" its not about internetless pc but i just wanted to write

seeing how they are still here, i think it's easy to assume that it must be hard for them to violate my computer, simply visiting website is hardly any dangerous, unless you run some random script, and without downloading anything, i can't see how in the hell they could violate my machine

i'm actually interested about this, can a malicious user gain the control of your machine, without the need for him to send virus/trojan/malware/rat/rootkit/(website scrypt)ecc...and hoping that you click or install them or that you visit some obscure website?

i'm talking about a direct attack to your desktop, like a ddos, but with also the possibility for him to take control of your machine, i think not, but maybe i'm wrong

if you are referring to the reusing of the "R values" by blockchain.info . i have to say, it could be easily avoided if the simple rule of "always use every address once" was followed, it could have been prevented.


i have experienced a "TCP SYN Flood attack" which is a kind of DDoS attack. the attacker needs your IP to do this kind of attack AFAIK. besides i wasn't doing anything out of the ordinary.

i must add that the attack was simply blocked by my dear AntiVirus (Eset Smart Security) and i blocked the attacker's IP afterwards, just to be safe.

Reusing addresses are alright except it compromises privacy. Reused 'R values' were exposed due to Blockchain.info wallet's bug, not user's fault.

or your bitcoin keys already being leaked from the last time you connected to the internet, it would be safer if the PC was never connected to the internet.

at some point you have to connect your pc to the internet, whether you want it or not. just make sure before you do anything, your pc is clean and safe. then you don't have to worry.

I put my bitcoin on my mobile and I don't really connect on the internet much using my mobile. So I think it is secure. Plus, I don't let other people touch my mobile and I don't carry it much on the public. I only open it once I have an incoming payment just to check. This phone is an option phone. My wife and I share the same phone for contacts and she got this non-android mobile she uses as it lasts for a day or two.

that is what i said, it was blockchain.info fault and it was unforgivable.
all i am saying is, everywhere you look it is recommend that you should use every address just once, and this simple act could have prevented their losses.

you must back up private key before you shutdown
you can back up on Hardisk external or Flashdisk
cause we not know after shutdown PC we can turn on it, or some one steal your PC

it depends on whether the security of the site is secure enough and the procedures implemented so that they don't know your private key, either partially or fully. Example, greenaddress.it. They require at least 2 signatures and they cant steal it by using the only private key they have.
The backup part is kind of mandatory for everyone, regardless of the uptime. Stealing your PC is also easy if its turned on, main part is securing your private key. The only concern is that SSD have the potential to lose data if they are of the poor grade or stored at high temperature after a long time.

according to me there are 2 ways a person can steal your bitcoins
1) having acces to your computer while you are connected to internet
2) physically accessing your computer to do a theft
a person can also steal your data if you have stored it in cloud service.

We can back up not in 1 place to safe it, iam using online cloud too like google cloud and i encrypt it before upload