Blockchain technology cyber risks and issues: overview [United Kingdom]

The Tulip Trading Case Changed Everything

In 2022, Tulip Trading sued 16 Bitcoin developers after a cyber-attack deleted private keys controlling $4.5 billion in digital assets. Their argument was blunt: the developers owed you a fiduciary duty to fix this. Issue a software patch. Get our money back.

The High Court said no.

But then, critically, the Court of Appeal said maybe. The case raised a serious issue to be tried.

Why this matters: The question of whether blockchain developers owe users a duty of care remains unsettled English law. And that's creating uncertainty for every organization deploying blockchain technology.

The practical upshot? If something goes wrong on a blockchain, it's currently unclear whether the developers who built it owe you anything.

Here's What Blockchain Actually Protects (And What It Doesn't)

What Blockchain Does Right

Blockchain technology is genuinely strong at what it does:

No single point of failure. Unlike centralized databases, a blockchain attack on one or a few nodes doesn't compromise the entire system. Other nodes maintain ledger integrity and keep processing transactions.

Immutability via distribution. Because every node holds an identical copy of the ledger, any attempt to alter historical transactions is immediately detectable. Consensus mechanisms continuously validate both new blocks and past transactions.

Cryptographic integrity. Public-private key encryption and cryptographic hash functions mean that tampering with data changes hash values that other participants immediately spot.

Resilience through transparency. It's harder to corrupt a blockchain with malware when thousands of participants can instantly see and verify changes.

What Blockchain Can't Protect

Now for the uncomfortable part. Most reported blockchain cyber attacks succeed by ignoring the blockchain entirely:

Private key theft. Hackers steal your keys, not your blockchain. Once they have your keys, they drain your accounts while the blockchain merrily records the transactions as valid. This is how cryptocurrency thefts typically happen, and the blockchain itself remains intact.

Wallet vulnerabilities. Digital wallet providers promise to manage your keys and minimize your risk. But their security depends on passwords, device authentication, and multi-factor controls that humans must properly use. One phishing email, one weak password, one compromised phone, and your assets are gone.

Oracle manipulation. Blockchains need external data (pricing, transaction details, real-world events). These "oracles" sit outside the blockchain's consensus validation mechanisms and are more vulnerable to tampering. Hackers can compromise an oracle and feed false information into your smart contracts.

Code vulnerabilities. In 2016, hackers exploited a coding defect in the DAO (built on Ethereum) and stole over $50 million in tokens. In 2024, two brothers were indicted for exploiting a vulnerability in Ethereum's transaction validation protocol to steal $25 million. The blockchain worked perfectly. The code didn't.

The edge is where attacks happen. Your interface with the blockchain, your wallet software, your private key storage, your authentication system, is the gateway for cyber-attacks. The blockchain itself is the least likely vector.

The Real Vulnerabilities You Need to Address

1. Private Key Management Is a Nightmare—And That's by Design

Blockchain's genius is that private keys can't be reproduced. This makes them theoretically secure. It also means if you lose your key, you lose everything forever. No reset link. No customer service. No recovery.

What you need to do:

• Understand exactly how your organization will manage private keys (on-premises hardware wallets? cloud-based custodians? multi-signature arrangements?)
• Implement role-based access controls for key management
• Use hardware wallets or cold storage for high-value assets
• Require multi-factor authentication for any key access
• Have a documented, tested process for key rotation and backup (without exposing backups)
• Consider custody solutions only from providers with robust cybersecurity practices and appropriate insurance

Red flag: If your blockchain implementation doesn't have a documented private key management policy, you're not ready to deploy.

2. Wallet Providers Are Trust Intermediaries; Treat Them That Way

Digital wallet providers (Coinbase, Kraken, hardware wallet manufacturers, etc.) are your human vulnerability point. They hold keys, manage authentication, and critically, they're profitable targets for hackers.

What you need to do:

• Conduct due diligence on any wallet provider or custody solution before you use it
• Understand their security architecture and disaster recovery procedures
• Verify they have cyber insurance and ask about claims history
• Implement governance controls so no single person can authorize key access
• Use device authentication (hardware keys, specific approved devices) in addition to passwords
• Require multi-factor authentication on all wallet access
• Monitor your wallet provider's security advisories and incident reports

Red flag: If a wallet provider can't clearly explain their security model or has experienced breaches, keep walking.

3. External Data (Oracles) Are Your Smart Contract's Weakest Link

Your blockchain is only as trustworthy as the external data feeding it. A corrupted oracle can inject false information into smart contracts before the blockchain ever sees it.

What you need to do:

• Use multiple, independent oracle providers (don't rely on one source)
• Implement circuit breakers that pause smart contracts if oracle data looks anomalous
• Monitor oracle data feeds for tampering or manipulation
• Build authentication between your smart contracts and oracle providers
• Document which oracles feed which contracts and why you trust them
• Consider using decentralized oracle networks (Chainlink, Uniswap) rather than single providers

Red flag: A blockchain implementation that relies on a single oracle provider is a single point of failure.

4. Code Vulnerabilities Are Real And They're Your Responsibility

Blockchain applications are code. Code has bugs. Some bugs are harmless. Some have cost tens of millions in stolen funds.

What you need to do:

• Conduct a security audit of any blockchain code before deployment (especially for smart contracts)
• Use formal verification tools to mathematically verify smart contract logic
• Implement staged rollouts rather than deploying entire systems at once
• Maintain continuous vulnerability scanning and patch management
• Keep abreast of emerging threats (quantum computing will eventually make current encryption obsolete)
• Have a vulnerability disclosure policy and incident response plan for code exploits
• Test your update/patch procedures before you actually need them

Red flag: Deploying unaudited smart contracts to handle significant financial transactions is gambling with your organization's assets.

5. Platform and Operating System Vulnerabilities Still Matter

Your blockchain runs on servers with operating systems. Those servers have hardware and software vulnerabilities just like any other computing environment.

What you need to do:

• Treat blockchain infrastructure like any other business-critical system
• Implement patch management across all servers and platforms
• Run vulnerability scans regularly
• Segment blockchain networks from general IT infrastructure
• Monitor for known CVEs affecting your hardware and software
• Keep detailed inventory of all components in your blockchain stack

The Regulatory Horizon: It's Getting Tighter

You're currently not subject to specific UK blockchain regulations. But that window is closing.

Network and Information Systems Regulations 2018 (NIS 2018): Blockchain operators may already fall within the definition of "relevant digital service providers" (RDSPs), triggering cybersecurity obligations.

NIS2 (EU Directive 2022/2555): The EU's updated directive imposes minimum cybersecurity standards on cloud computing providers. Since blockchain operators often use cloud infrastructure, this could apply to UK-based blockchain operators serving EU customers (extraterritorial effect).

Future UK legislation: As blockchain moves into high-risk sectors (finance, healthcare, supply chain), the UK government is increasingly likely to introduce minimum security standards. The government has already consulted on private permissioned blockchains for customs border processing and Land Register updates.

Translation: Start building cybersecurity practices now that will survive regulation later. If you wait for mandated standards, you'll be retrofitting security into already-deployed systems.

The Unresolved Question: Does Anyone Owe You Anything?

The Tulip Trading case left a legal vacuum: Do blockchain developers owe users a duty of care?

Currently in English law, the answer is: unclear.

The High Court said developers don't owe fiduciary duties because doing so would mean undivided loyalty to one user while disadvantaging others. The Court of Appeal said the question is serious enough to go to trial. And the Law Commission has proposed new legislation on digital assets (though not specifically addressing duty of care).

What this means for you:

• There's currently no legal obligation for blockchain developers to fix security issues affecting your assets
• If you suffer a loss due to blockchain code vulnerabilities, you may have no recourse against the developers
• This uncertainty makes private blockchains (where you control governance) safer than public ones (where developers are distributed and unaccountable)
• Until legislation clarifies this, assume you bear the entire risk, not the developers

Public vs. Private: A Security Lens

This changes your blockchain choice:

Public blockchains (Bitcoin, Ethereum):

• ✅ Massive security through distributed validation
• ❌ No central authority to fix bugs or security issues
• ❌ Developers owe you nothing (legally speaking)
• ❌ Better for you if you're just a user or investor
• ⚠️ Riskier if you're building applications on top

Private blockchains (permissioned networks):

• ✅ You control governance and can issue patches
• ✅ You can implement consistent authentication and controls
• ✅ Smaller, trusted participant base
• ❌ Depends on fewer validators—more vulnerable to 51% attacks if not carefully governed
• ❌ Higher operational overhead
• ✅ Better for sensitive transactions between known parties
• ✅ Better if you need to comply with data protection laws (easier to encrypt sensitive data)

Your Action Plan

This quarter:

1. Inventory your blockchain exposure. Are you currently using blockchain? Planning to? Map all blockchain applications, who operates them, and what they handle.
2. Audit private key management. If you're using blockchain, document exactly how you manage private keys. If you can't explain it in writing, it's not secure enough.
3. Evaluate wallet providers. If you use custody solutions, conduct formal due diligence on their security practices.
4. Security-audit your code. Any smart contracts you're deploying should be formally audited. Yes, it's expensive. The cost of a breach is worse.
5. Map your oracles. Document where external data enters your blockchain applications and how you validate that data.

Next quarter:

1. Prepare for regulation. Build documentation showing how your blockchain implementation meets the five UK AI regulatory principles (safety, transparency, fairness, accountability, redress) and NIS 2 requirements.
2. Develop an incident response plan. What happens if your oracle gets compromised? Your keys get stolen? Your code has a vulnerability? Have a plan now.

The Bottom Line

Blockchain itself is remarkably secure. The problem is everything around it—end users, keys, wallets, external data, code. And legally speaking, if something goes wrong, it's still unclear whether anyone owes you a remedy.

Build your blockchain implementations assuming:

• You bear all the security risk
• Developers won't fix problems for you (until law changes)
• The blockchain will work perfectly while everything at its edges fails
• Regulation is coming, and it will impose minimum security standards

Do that, and you're ahead of most organizations currently deploying blockchain.

Your Move

Are you currently using blockchain? What's your biggest security concern, private key management, smart contract code, external data feeds, or end-user vulnerabilities? Drop a comment.

And if you're building blockchain applications (especially smart contracts), have you conducted a formal security audit? That's the difference between innovation and expensive mistakes.

— Arunima

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