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

Barely three weeks after hackers linked to North Korea exploited social engineering tactics to breach the cryptocurrency trading firm Drift, another significant exploit has been attributed to the nation, this time targeting Kelp, a restaking protocol connected to LayerZero's cross-chain infrastructure. This attack signifies an evolution in the tactics employed by North Korea-linked hackers, who are now exploiting fundamental assumptions underlying decentralized systems, rather than merely seeking out vulnerabilities or stolen credentials. The cumulative effect 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 pattern. You cannot resolve these issues merely by patching them; it's about addressing the procurement schedule.' The breaches of Drift and Kelp resulted in the theft of over $500 million in just over two weeks. The Kelp breach did not involve breaking encryption or decoding keys; instead, attackers manipulated the data input into the system, forcing it to rely on compromised information and thus approving transactions that did not occur. 'The security failure is straightforward: a signed lie is still a lie,' Urbelis noted. 'Signatures guarantee the sender's identity, not the truthfulness of the message.' In simpler terms, the system verified the sender but not the message's accuracy, making this exploit more about manipulating the system's setup than about using a sophisticated new hack. David Schwed, COO of blockchain security firm SVRN, stated, 'This attack wasn't about breaking cryptography; it was about exploiting the system's configuration.' A key issue was the use of a single verifier to approve cross-chain messages, a choice made for speed and simplicity but one that removes a critical safety layer. Following the incident, LayerZero recommended using multiple independent verifiers for transaction approval, similar to requiring multiple signatures on a bank transfer. However, some have argued that LayerZero's default setup was to use a single verifier. Schwed emphasized, 'If a configuration is identified as unsafe, it should not be offered as an option. Security that relies on everyone reading the documentation and getting it right is not realistic.' The impact has not been limited to Kelp, as its assets are utilized across multiple platforms, leading to a ripple effect. 'These assets are essentially a chain of IOUs, and the chain is only as strong as the controls on each link,' Schwed explained. When one link breaks, others are affected, turning a single exploit into a broader stress event. For instance, lending platforms like Aave, which accepted the impacted assets as collateral, are now facing losses. The attack also highlights a discrepancy 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 broadened the perspective, stating, 'Decentralization is not a property a system has; it's a series of choices. And the stack is only as strong as its most centralized layer.' In practice, this means that even systems appearing to be decentralized can have weak points, particularly in less visible layers such as data providers or infrastructure, which are increasingly the focus of attackers. This shift may explain why Lazarus, a group linked to North Korea, has recently targeted cross-chain and restaking infrastructure, components that move assets between systems or allow them to be reused. These layers are critical but complex, often underlying more visible applications, and they tend to hold significant 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 kind of weakness; it demonstrated how exposed the ecosystem remains to familiar vulnerabilities, 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 more expensive to ignore.