North Korea's Cryptocurrency Theft Tactics Are Evolving, with DeFi Being a Prime Target

Less than three weeks after hackers linked to North Korea used social engineering to breach the crypto trading firm Drift, another major exploit has been carried out against Kelp, a restaking protocol connected to LayerZero's cross-chain infrastructure. This attack suggests that North Korea-linked hackers are adapting their methods, no longer just searching for vulnerabilities or stolen credentials, but also exploiting fundamental assumptions built into decentralized systems. The combined impact of these two incidents points to a more organized effort by North Korea to hijack funds from the crypto sector, amounting to over $500 million stolen in just over two weeks. According to Alexander Urbelis, chief information security officer and general counsel at ENS Labs, 'This is not a series of incidents; it is a cadence. You cannot patch your way out of a procurement schedule.' The Kelp exploit did not involve breaking encryption or cracking keys; instead, attackers manipulated the data feeding into the system, forcing it to rely on compromised inputs and approve transactions that never occurred. The security failure lies in the system's design, which checked the sender of the message but not the message's accuracy. Experts view this as exploiting the system's setup rather than a new hacking technique. A key issue was Kelp's reliance on a single verifier to approve cross-chain messages, a configuration choice that removed a critical safety layer. In response, LayerZero has recommended using multiple independent verifiers, similar to requiring multiple signatures on a bank transfer. However, some argue that LayerZero's default setup was to have a single verifier, highlighting a gap between the marketed decentralization and its actual implementation. David Schwed, COO of blockchain security firm SVRN, noted, 'Security that depends on everyone reading the docs and getting it right is not realistic.' The impact has spread beyond Kelp, affecting lending platforms like Aave that accepted the impacted assets as collateral, turning a single exploit into a wider stress event. This exposes the chain of IOUs in DeFi systems, where the chain is only as strong as the controls on each link. When one link breaks, others are affected. The attack also highlights the gap between the marketed decentralization and its actual implementation, with Urbelis stating, 'Decentralization is not a property a system has. It is a series of choices. And the stack is only as strong as its most centralized layer.' This means even seemingly decentralized systems can have weak points, particularly in less visible layers. The shift in attackers' focus towards these layers, such as cross-chain and restaking infrastructure, may explain the recent targeting by Lazarus. These layers are critical, complex, and often hold large amounts of value, making them attractive targets. As Lazarus adapts, the biggest risk may not be unknown vulnerabilities but known ones that are not fully addressed. The Kelp exploit did not introduce a new weakness but showed how exposed the ecosystem remains to familiar ones, especially when security is treated as a recommendation rather than a requirement.