_ Here's how it works: Anybody can ask a question Anybody can answer The best answers are voted up and rise to the top up vote 2 down vote favorite I opened bitcoin-qt after not mining for a couple months and found that I suddenly have no more bitcoins!And I see that there were 2 transactions that I did not authorize sending my coins to other addresses!Is there anything I can do to get my coins back?client security up vote 1 down vote Probably not.You can try to look at the addresses the coins were transferred to (or, if those were since sent elsewhere, at those addresses too) and see if you can figure out who they belong to.If the thief is somewhat competent, however, it's a good bet that he's made it very hard to track.If you can determine the identity, you might be able to take them to a court (small claims, civil, criminal...I don't know, and might depend on how many bitcoins were stolen, and where in the world you and your thief live) to demand the bitcoins (or equivalent value) back.

But as far as the Bitcoin protocol itself goes: no, you cannot reverse the transaction.To prevent this in the future, make sure that your computer is free of malware, always encrypt your wallet with a secure password, and consider using an offline wallet.bitcoin rsi's Securing your wallet page for other tips.pakai bitcoinAre you sure that the addresses don't belong to you, maybe in some online service you used and forgot about?ethereum file storageup vote 0 down vote No, sorry but "fortunately" you can't do anything, otherwise people could pay for goods and services and then get back the bitcoin used (it's called double spending).ethereal planets unity

The analogy with fiat money is when someone picks your pocket, asking your bank for a refund for the cash you had won't help.ethereum music industrySome best practices for achieving good security are: take care about system password for online wallet install official/trusted bitcoin wallet software use offline wallets if you hold many bitcoins (create the wallet with an off-line computer!)bitcoin кошелек iosdo not put many bitcoin in a single exchange because they control your money (mtgox), or wait for distributed exchange Your Answer Sign up or log in Sign up using Google Sign up using Email and Password Post as a guest Name Email discard By posting your answer, you agree to the privacy policy and terms of service.Browse other questions tagged client security or ask your own question.

Unknown hackers have released a large cache of files stolen from notorious Italy-based spyware firm Hacking Team, revealing that the company enabled its clients to hack computers and monitor cryptocurrency activity on those machines.According to a report by security news provider CSO, the trove of data included internal emails, payment invoices and product descriptions.Among the products listed in a slideshow prepared by CSO are computer monitoring programs that, among other capabilities, can view “cryptocurrency transactions”, naming bitcoin and litecoin specifically.The three products, which offer surveillance tools for the Mac OSX, Linux and Windows systems, enable licensees to monitor activity on a computer affected by the spyware.Users can capture files and email, record sound using the microphone and track the position of the device, among other functionalities.Hacking Team’s reputation stems largely from its association with repressive governments, to which it provides technology that enables hacking, mass surveillance and data collection.

The leaked files show that the company counts US agencies among its clientele – the Federal Bureau of Investigation, the Department of Defense and the Drug Enforcement Agency, in particular – as well as Saudi Arabia, Oman, Azerbaijan, Turkey, Sudan and other regimes.Employee Christian Pozzi later took to Twitter to denounce the hack, accusing those behind the release of lying and stating that the firm was working with law enforcement officials.Pozzi later deleted his account.Reports indicate that cybersecurity researchers analyzing the released files have already identified several significant exploits developed by Hacking Team.This is an archived post.You won't be able to vote or comment.I'm devastated, got hacked and lost 40.5 BTCs.Please, help me find who did it (self.Bitcoin)submitted by Hello guys.Really sad day, I had 40 BTCs in my PC's Wallet and tonight they flight.Don't know what happened, the PC was offline yesterday night so I guess that somebody must have copied it and emptied yesterday, it had a lot of different addresses because of changes and all were emptied, so I'm pretty sure I was keylogged and my wallet copied.

This is the hacking transaction: https://blockchain.info/tx/343d79c2917ad16911b435dfe67d5ac71920ad635a77ed67de324689cb38f557 All those addresses are from my wallet, main one is 1JXCsUGCoeiqACgxTRBDLB6wgRz31XiHaE , has coins from March 2013.I know that I've been stupid and that I should have had that on a cold storage, lesson learned.PS: Anyone up to try to find the hacker?π Rendered by PID 14007 on app-210 at 2017-06-24 10:42:37.016720+00:00 running 3522178 country code: SG.An early bitcoin adopter has made a plea for bitcoin consumers to migrate to more secure bitcoin storage systems after having 750 BTC (about $280,000 at press time) stolen from him while on vacation.Bitcoin entrepreneur Leo Treasure told CoinDesk his misfortune should serve as a cautionary tale for everyone.Whether they store bitcoins online, on hard drives or in cold storage, he implored users to switch to more secure multi-signature ('multi-sig') wallets as soon as possible.Though he holds little hope of ever recovering his bitcoins and isn't expecting the authorities to help, he is following the lead of others who have suffered bitcoin-related crimes and promising 50% of the stolen amount as a reward to anyone who can help recover it.

Treasure, a former computer science student and bitcoin entrepreneur from Perth, Australia, told CoinDesk he was traveling in Bali and didn't think connecting to public Wi-Fi could be a security issue as his bitcoins were stored locally.Upon reading about the 'Bash Bug', he checked one of his bitcoin addresses on the block chain and noticed an unfamiliar transaction.Once he synchronized the Bitcoin-Qt client on his MacBook, the 'sent' records confirmed the worst.A series of transactions leading to unfamiliar addresses had occurred from his wallet.It was no small hack – the amount stolen represented the majority of Treasure's bitcoin holdings, leaving him with only small amounts stored elsewhere.Treasure admitted that keeping such a large stash on his hard drive wasn't a good idea, but confessed to having the "could never happen to me" feeling of false comfort that precedes many a disaster, saying: "I feel like an idiot being so blasé about computer security and thinking I'd be alright [...] I'd just given a talk at the Perth bitcoin meetup saying how I was going to move all my coins over to multi-sig, but I didn't act quick enough."

, which quoted Gavin Andresen's comments in his State of Bitcoin Address in Amsterdam last May.In the article, CEO and co-founder of multi-sig wallet provider BitGo Will O'Brien wrote that despite Andresen's call over 99% of all bitcoins are still stored in single-signature addresses.Multi-sig addresses, he wrote are "the only viable solution for securing bitcoins".Multi-sig bitcoin addresses are the result of Bitcoin Improvement Proposal (BIP) 16, which was created in 2012 and implements something called 'pay to script hash' (P2SH) technology.Bitcoin addresses generated using P2SH begin with a '3' instead of the usual '1', and require multiple keys for their balances to be spent.The standard model is to require two out of three keys to spend from a balance – of those keys, one goes to the user, one to the service (exchange or wallet) provider and another to a trusted third party.A user may choose to keep the third key in a safe place instead.Therefore, the owner of the coins may access the balance even if the service provider is shut down or goes out of business (or is run by a malicious operator) and, just as importantly, a single device stolen or compromised by a hacker is not enough to steal the coins.

BitGo published a white paper on the topic of P2SH in 2013 and open-sourced its own code to build trust.Developer Ben Smith, who created multi-sig bitcoin wallet and social payment system Ninki, agreed this technology would solve a lot of problems.He said: "Multi-signature wallets combined with strong passwords and two-factor authentication massively reduce the attack surface, making these simple exploits a thing of the past."Unfortunately, security is often something people don't consider until after suffering an attack, and popular services are moving slowly to implement multi-sig.Besides, BitGo, Treasure cited FrozenBit (still in invite-only beta) and GreenAddress as examples of multi-sig wallet solutions.Another service, QuickWallet, was recently acquired by major Chinese exchange Huobi.The local-storage wallet Armory, often favored by more tech-savvy and security conscious bitcoin users, has a form of multi-sig called 'Lockboxes'.Treasure's involvement in bitcoin included importing 15 Lamassu ATMs to Australia, and his father Bret is a board member with the Bitcoin Association of Australia and chairman of the Australian Web Industry Association.

He was featured in the following Australian TV news report on bitcoin: Treasure's trip to Bali involved discussions with Bitcoin Indonesia founder Oscar Darmawan and other participants in the BitIslands project, which aims to turn Bali into a digital currency haven.He had obtained the majority of his bitcoins by taking out a AUD$20,000 loan.According to a Perth newspaper article, his own stash was in the 1,000 BTC realm.Treasure's remaining coins are in multi-sig wallets and Casascius physical coins.Treasure said he plans to move all of them to multi-sig alternatives once home again and on a machine he trusts: "I don't know if the hacker was only able to remotely get read access to my home directory (which had numerous unencrypted backups) or whether there's a customised root kit avoiding detection and logging my every keystroke.I'm buying a new computer and cloning my hard drive for evidence purposes.""Don't ever sweep cold wallets 'til you're absolutely sure there's no keylogger on your machine."