North Korea's Cryptocurrency Theft Strategy is Evolving, with DeFi Being a Prime Target

Less than three weeks after hackers linked to North Korea used social engineering to breach the cryptocurrency trading firm Drift, another major exploit has been carried out, this time targeting Kelp, a restaking protocol connected to LayerZero's cross-chain infrastructure. This attack signals an evolution in the tactics employed by North Korea-linked hackers, who are no longer just seeking out vulnerabilities or stolen credentials but are now exploiting fundamental assumptions built into decentralized systems. The combined impact of these incidents suggests a more organized effort by North Korea to siphon funds from the cryptocurrency sector. According to Alexander Urbelis, Chief Information Security Officer and General Counsel at ENS Labs, 'This is not a series of isolated incidents; it's a coordinated cadence. You cannot patch your way out of a procurement schedule.' More than $500 million was stolen across the Drift and Kelp exploits in just over two weeks, highlighting the scale and sophistication of these attacks. The Kelp breach 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 actually occurred. This exploit underscores a simple yet critical security failure: the system checked the authorship of messages but not their truthfulness. David Schwed, COO of blockchain security firm SVRN, noted, 'This attack wasn't about breaking cryptography; it was about exploiting how the system was set up.' A key issue was the configuration choice to rely on a single verifier to approve cross-chain messages, which, while faster and simpler to set up, removes a critical safety layer. In the aftermath, LayerZero has recommended using multiple independent verifiers to approve transactions, akin to requiring multiple signatures on a bank transfer. However, some have pushed back on this recommendation, arguing that LayerZero's default setup was to have a single verifier. The fallout from the Kelp exploit has not been contained and has affected broader DeFi systems, as assets used across multiple platforms can spread problems. 'These assets are a chain of IOUs,' Schwed said, 'and the chain is only as strong as the controls on each link.' When one link breaks, others are affected, leading to a wider stress event, as seen with lending platforms like Aave that accepted impacted assets as collateral and are now dealing with losses. The attack also highlights a gap between the marketing of decentralization and its actual implementation. 'A single verifier is not decentralized; it's a centralized decentralized verifier,' Schwed pointed out. Urbelis added, '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.' In practice, this means that even systems that appear decentralized can have weak points, particularly in less visible layers such as data providers or infrastructure, which are increasingly the focus of attackers. The recent targeting by Lazarus, a group linked to North Korea, of cross-chain and restaking infrastructure, underscores this shift. These layers are critical but complex and often sit underneath more visible applications, holding large amounts of value and making them attractive targets. As Lazarus continues to adapt, the biggest risk may not be unknown vulnerabilities but known ones that are not fully addressed. The Kelp exploit did not introduce a new kind of weakness; it showed how exposed the ecosystem remains to familiar ones, especially when security is treated as a recommendation rather than a requirement. As attackers move faster, this gap is becoming both easier to exploit and far more expensive to ignore.