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

Less than three weeks after North Korea-linked hackers used social engineering to infiltrate the crypto trading firm Drift, hackers with ties to the nation appear to have executed another significant exploit targeting Kelp, a restaking protocol connected to LayerZero's cross-chain infrastructure. This attack suggests an evolution in the tactics employed by North Korea-linked hackers, moving beyond exploiting bugs or stolen credentials to manipulating the fundamental assumptions underlying decentralized systems. The combined incidents of the Drift and Kelp exploits, which resulted in the theft of over $500 million in just over two weeks, point to a more organized campaign than a series of isolated hacks, as North Korea continues to escalate its efforts 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 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 input into the system, forcing it to rely on compromised data and approve non-existent transactions. 'The security failure is simple: a signed lie is still a lie,' Urbelis noted. 'Signatures guarantee authorship; they do not guarantee truth.' In essence, the system verified the sender of the message but not the message's accuracy itself. For security experts, this exploit highlights the manipulation of how the system was set up rather than a novel hacking technique. David Schwed, COO of blockchain security firm SVRN, emphasized, 'This attack wasn’t about breaking cryptography; it was about exploiting how the system was set up.' A key issue was the configuration choice of relying on a single verifier to approve cross-chain messages, a setup that, while faster and simpler, removes a critical safety layer. Following the exploit, LayerZero recommended using multiple independent verifiers to approve transactions, akin to requiring multiple signatures on a bank transfer. However, some in the ecosystem have disputed this recommendation, arguing that LayerZero's default setup was to use a single verifier. Schwed argued, 'If you’ve identified a configuration as unsafe, don’t ship it as an option. Security that depends on everyone reading the docs and getting it right is not realistic.' The impact of the exploit has not been contained to Kelp, as its assets are utilized across multiple platforms, leading to a ripple effect where problems can spread. 'These assets are a chain of IOUs,' Schwed explained. 'And the chain is only as strong as the controls on each link.' When one link breaks, others are affected, turning a single exploit into a broader stress event. In this case, lending platforms like Aave, which accepted the impacted assets as collateral, are now dealing with losses. The attack also reveals a discrepancy between the marketing of decentralization and its actual implementation. 'A single verifier is not decentralized,' Schwed said. 'It’s a centralized decentralized verifier.' Urbelis broadened this perspective, 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.' In practice, this means that even systems appearing decentralized can have weak points, particularly in less visible layers such as data providers or infrastructure, where attackers are increasingly focusing their efforts. This shift may explain the recent targeting by the Lazarus group, which has begun focusing on cross-chain and restaking infrastructure, the parts of crypto that facilitate asset movement between systems or allow assets 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 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 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.