Common Bitcoin Attacks and How to Defend Against Them

Common Bitcoin Attacks

Most Bitcoin isn't lost to sophisticated cryptographic attacks. It's lost to social engineering, operational mistakes, and basic security failures. Here are the real threats and practical defenses.

Social Engineering Attacks

SIM Swap Attacks

An attacker convinces your mobile carrier to transfer your phone number to their SIM. They then reset passwords on accounts using SMS 2FA. Defense:

• Never use SMS-based 2FA for crypto accounts
• Use hardware security keys (YubiKey) or authenticator apps (Aegis, not Google Authenticator)
• Set a PIN/passphrase with your carrier for account changes
• Don't link your phone number to crypto accounts

Phishing

Fake websites, emails, and support channels that trick you into revealing seed phrases or signing malicious transactions. I've seen sophisticated phishing targeting Sri Lankan crypto users via Telegram and WhatsApp groups.

• Rule #1: No legitimate service will ever ask for your seed phrase. Ever.
• Bookmark exchange URLs — never click links from emails or messages
• Verify hardware wallet firmware through official channels only

The $5 Wrench Attack

Physical coercion — someone threatens you to hand over your Bitcoin. Defenses:

• Plausible deniability: Use a passphrase (25th word) to create a hidden wallet. Show the attacker the non-passphrase wallet with a small amount
• Multisig: You physically can't hand over funds that require keys in other locations
• Don't advertise: Don't tell people how much Bitcoin you hold

Technical Attacks

Clipboard Hijacking

Malware that monitors your clipboard and replaces Bitcoin addresses with the attacker's address when you copy-paste. This is extremely common.

• Always verify the full address on your hardware wallet screen before signing
• Compare the first AND last 8 characters of the address
• Use QR codes instead of copy-paste when possible

Fake Hardware Wallets

Tampered devices sold through unofficial channels that either have known seed phrases or modified firmware. Defense:

• Buy only from official manufacturer websites
• Verify the device's security seal and anti-tamper mechanisms
• Generate your own seed — never use a pre-generated one
• Verify firmware signatures

Dusting Attacks

Tiny amounts of Bitcoin sent to your address to track your spending patterns through chain analysis. If you spend the dust alongside your other UTXOs, the attacker can link your addresses.

• Use coin control (available in Sparrow and Electrum) to identify and isolate dust
• Don't spend dust UTXOs — leave them or consolidate them separately

Operational Security

• Use a dedicated device for Bitcoin transactions — not your daily browsing laptop
• Run your own node to verify transactions without trusting a third party
• Keep software updated — wallet software, firmware, operating system
• Use a VPN or Tor when transacting to prevent IP correlation
• Practice recovery before you need it — test restoring from backup

Security isn't a product you buy — it's a practice you maintain. The moment you think you're safe is when you're most vulnerable. Stay paranoid, stay humble, stay sovereign.

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