Multisig Failures Dominate as $3.1B Is Lost in Web3 Hacks in the First Half

Crypto investors lost around $3.1 billion to hacks in the first half of the year, with the first quarter alone topping all the losses of 2024, according to a report from security firm Hacken.

The most intriguing finding was that multisignature wallets, which require several people to sign a transaction before it is executed were frequently compromised due to user interface tampering and signer mismanagement.

The infamous first-quarter hack of centralized exchange Bybit resulted in a $1.46 billion breach when a compromised safe‑wallet interface tricked authorized signers.

It was the third quarter in a row in which the single largest hack originated from multisig lapses.

The first half also saw $300 million in rug pulls. Phishing and social engineering campaigns also contributed heavily, chalking up nearly $100 million. Smart contract vulnerabilities were negligible, accounting for less than 2% of total losses.

Smart contract bugs, for example the $223M Cetus overflow, attributed to the majority of attacks in the second quarter of 2025.

Access-control issues remain the dominant theme, responsible for over 80% of every stolen dollar this year.

Hacken urged a shift from reactive auditing to real-time operational defenses. Its report recommends the use of of AI-powered monitoring systems that continuously validate multisig transactions, detect deviations in signer activity and trigger automated safeguards.

It also recommends that both CeFi and DeFi projects treat signer protocols, multisig front-ends, and human workflows as security-critical infrastructure, bolstering them with automation, training and tighter governance.

UPDATE JULY 24, 13:49 UTC: Updates figure from $2 billion to $3.1 billon. Adds context in regards to second quarter of this year.