The blockchain allows users to record transactions across a distributed network of computers. The server is secure, and transactions are permanent, making verification easy. Transactions are also conducted directly between users without needing an outside intermediary. A blockchain protocol will tell computers how to verify and aggregate transactions. In addition, the blockchain keeps a history of all transactions without users being able to change the data.
Cryptocurrency like bitcoin is the most standard type of blockchain technology. Many organizations use crypto currencies for large financial transactions. Some legal experts even allow their clients to pay for services with cryptocurrencies. Additionally, business and technology lawyers will no doubt encounter cryptocurrency or other technologies in some of their cases. Legal professionals’ interactions with blockchain include eDiscovery verification, tele-advocate services, medical records, healthcare databases, and smart contracts.
Table of Contents
What Is Blockchain?
Blockchain is a decentralized digital ledger technology that records transactions across multiple computers in a way that makes the data secure, transparent, and nearly impossible to alter once confirmed.
Instead of being stored in one central database (like a bank server), blockchain data is distributed across a network of computers called nodes.
Simple Definition
A blockchain is a chain of digital “blocks” that store transaction data, linked together using cryptography and secured by a decentralized network.
How Blockchain Works (Step-by-Step)
- Transaction Initiated
A user requests a transaction (e.g., sending cryptocurrency). - Transaction Broadcast
The request is shared with a network of computers (nodes). - Verification
Nodes validate the transaction using a consensus mechanism. - Block Creation
Verified transactions are grouped into a block. - Block Added to Chain
The new block is cryptographically linked to the previous block. - Permanent Record
The transaction becomes immutable and transparent.
Key Features of Blockchain
| Feature | Explanation |
| Decentralization | No single authority controls the network |
| Transparency | Transactions are visible on public blockchains |
| Immutability | Once recorded, data cannot easily be changed |
| Security | Uses advanced cryptography |
| Consensus Mechanism | Network agreement validates transactions |
Types of Blockchain
| Type | Description | Example |
| Public Blockchain | Open to anyone | Bitcoin |
| Private Blockchain | Restricted access | Enterprise supply chains |
| Consortium Blockchain | Controlled by group of organizations | Banking networks |
| Hybrid Blockchain | Mix of public & private features | Enterprise platforms |
Blockchain Hacking: Can Blockchain be Hacked?
| Attack / Risk Type | What It Is | Can It Hack Blockchain? | Typical Cost / Impact | Trusted Resource |
| 51% Attack | When a miner or group controls >50% of network hashing power | Yes — enables double spends & block reorgs on PoW chains | Impact: $10M+ (e.g., $61M on Bitcoin Gold) | CoinDesk — 51% attack risks https://www.coindesk.com/ |
| Smart Contract Exploit | Bugs in deployed contract code | Yes — drains funds/contracts behave incorrectly | Losses: $100K–$600M+ (DeFi exploits) | CertiK — Smart contract bugs https://www.certik.com/ |
| Sybil Attack | Fake identities overwhelm network | Sometimes — disrupts consensus/validators | Cost: Moderate (tokens or node costs) | MIT Press — Sybil attacks https://mitpress.mit.edu/ |
| Routing / BGP Hijack | Internet routing manipulation | Yes — delays blocks or isolates nodes | Cost: ~$1K–$10K (BGP manipulation services) | IEEE — BGP hijack study https://ieeexplore.ieee.org/ |
| Wallet Theft / Phishing | User keys stolen | Yes — steals funds, not core blockchain | Losses: $10K–$100M+ | Chainalysis report https://go.chainalysis.com/ |
| Consensus Flaws / Protocol Bugs | Design level vulnerabilities | Yes — chain reorgs, integrity issues | Impact: High if exploited | ETHSecurity research https://ethereum.org/ |
| Private Key Compromise | Leak/loss of user private key | Yes — direct theft from wallet | Losses: Highly variable | Ledger/MetaMask key risks https://ledger.com/ |
| Oracle Manipulation | Price feed tampering | Yes — DeFi contract mispricing | Losses: $1M+ | Oracle attack explained https://blog.chain.link/ |
| Social / Governance Exploit | Manipulating devs or upgrades | Indirect — can affect upgrade path | Impact: Medium | Ethereum research governance |
| Blockchain Bugs (e.g., replay attacks) | Protocol misuse | Yes — replays in forks | Impact: Moderate | Bitcoin wiki — replay protection https://en.bitcoin.it/ |
Estimated Impact / Cost Insights
| Category | Blockchain Layer | Typical Financial Impact |
| Protocol Attack (e.g., 51% or consensus bug) | Core chain | $10M–$100M+ depending on network & market cap |
| Smart Contract Exploit | Application layer | $100K–$600M+ (DeFi hacks) |
| User Wallet Theft/Phishing | User layer | $10K–$100M+ |
| Oracle Manipulation | Data feed layer | $1M–$100M+ |
| Defense Costs (Audits, Bug Bounties) | Preventive security | $50K–$2M+ per audit |
| Bug Bounty Rewards | Hacker rewards | $5K–$1M+ depending on severity |
Example: Large bug bounty programs like Immunefi and HackerOne pay up to $1M+ for critical blockchain vulnerabilities.
How Blockchain Improves Security Despite Risks
| Feature | Security Benefit |
| Decentralization | No single point of failure |
| Cryptographic Integrity | Immutable records |
| Consensus Mechanisms | Makes tampering costly |
| Open Source Audits | Community transparency |
Blockchain Hacking is Increasing
Recently, blockchain attacks have increased dramatically as hackers have discovered vulnerabilities exist. As of 2017, public data shows that hackers have stolen around $2 billion worth of cryptocurrencies. This recent activity makes it clear that, unfortunately, the blockchain is not tamper-proof, and users still need to be careful, especially when trading on the exchange.
Therefore, legal practitioners who contact blockchain should stay informed about the risks and new solutions. Furthermore, before using intelligent contracts or trading on a business, you should learn about previous attacks and relevant security measures.
However, it doesn’t seem like blockchain users should be too cautious as the technology is still very secure. Undoubtedly, the creators and admins will keep improving the security measures to reduce the hacking risk in the future.
Yes, Blockchain Can Be Hacked: 5 Ways It Can Be Done
| # | Attack Type | How It Works | Real-World Impact / Estimated Loss | Resource Link |
| 1 | 51% Attack | An attacker gains control of >50% of mining/hash power, allowing double-spending and chain reorganization. | Example: Bitcoin Gold suffered ~$18M+ in double-spend attacks. Estimated cost to attack small networks: $5,000–$100,000+ per hour (depending on hash rental). | CoinDesk – 51% attack explained: https://www.coindesk.com/learn/what-is-a-51-percent-attack/ |
| 2 | Smart Contract Exploit | Hackers exploit coding vulnerabilities in decentralized applications (DeFi protocols). | Example: Ethereum DeFi exploits have exceeded $600M+ in single attacks (e.g., Ronin Bridge). Audit costs for prevention: $50,000–$500,000+. | CertiK – Smart contract security: https://www.certik.com/resources/blog |
| 3 | Private Key Theft / Phishing | Users lose access when hackers steal wallet private keys via phishing or malware. | Global crypto phishing losses exceed $1B+ annually. Individual losses range $1,000–$100M+. Hardware wallets cost ~$5,000–₹15,000 ($60–$200). | Chainalysis Crypto Crime Report: https://go.chainalysis.com/crypto-crime-report.html |
| 4 | Oracle Manipulation | Attackers manipulate external price feeds used by DeFi smart contracts. | DeFi oracle attacks have caused $10M–$100M+ losses. Defensive oracle solutions can cost $20,000–$200,000 integration. | Chainlink – Oracle attack overview: https://blog.chain.link/what-is-a-blockchain-oracle/ |
| 5 | Sybil / Network Attack | Creating multiple fake nodes to influence consensus in weaker networks. | Lower-cost attack on small blockchains; may cost $1,000–$50,000 depending on validator requirements. | MIT Technology Review – Sybil attack explained: https://www.technologyreview.com/ |
Summary of Financial Impact
| Attack Category | Layer Targeted | Typical Financial Impact |
| 51% Attack | Core protocol | $10M–$100M+ |
| Smart Contract Hack | Application layer | $100K–$600M+ |
| Wallet/Key Theft | User layer | $1K–$100M+ |
| Oracle Exploit | Data layer | $10M–$100M+ |
| Sybil Attack | Network layer | Moderate disruption; varies |
Important Clarification
Blockchain itself (the core cryptographic ledger) is extremely secure, especially on large networks like:
- Bitcoin
- Ethereum
However, vulnerabilities usually occur at:
- The application layer (smart contracts)
- The user layer (private keys)
- The network layer (routing, Sybil attacks)
Why Large Blockchains Are Hard to Hack
| Security Feature | Why It Helps |
| Massive hash power | Makes 51% attacks extremely expensive |
| Decentralization | No single point of failure |
| Cryptography | Protects transaction integrity |
| Continuous auditing | Detects vulnerabilities early |
| Bug bounty programs | Incentivize responsible disclosure ($10K–$1M rewards) |
Conclusion
Blockchain hacks have recently drastically increased as hackers have discovered that vulnerabilities exist. Since 2017, public data displays that hackers have taken around $2 billion in cryptocurrency.