North Korea's Cryptocurrency Theft Tactics Are Evolving, with DeFi Being Frequently Targeted

Less than three weeks after hackers linked to North Korea used social engineering to breach the cryptocurrency trading firm Drift, it appears that hackers tied to the nation have carried out another significant exploit, this time targeting Kelp, a restaking protocol integrated into LayerZero's cross-chain infrastructure. This attack suggests an evolution in the tactics employed by North Korea-linked hackers, as they are no longer solely focused on identifying bugs or exploiting stolen credentials but are now manipulating the fundamental assumptions underlying decentralized systems. The cumulative effect of these two incidents points to a more organized effort by North Korea to intercept funds from the cryptocurrency sector, rather than a series of isolated hacks. 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.' More than $500 million was siphoned off through the Drift and Kelp exploits in just over two weeks. 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 thereby approving transactions that never actually occurred. As Urbelis noted, 'The security failure is simple: a signed lie is still a lie. Signatures guarantee authorship; they do not guarantee truth.' In essence, the system verified the sender of the message but not the accuracy of the message itself. For security experts, this exploit highlights the manipulation of how the system was set up rather than the discovery of 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 a configuration choice, where Kelp relied on a single verifier to approve cross-chain messages, a decision made for speed and simplicity but one that removed a critical safety layer. In response, LayerZero has recommended using multiple independent verifiers to approve transactions, akin to requiring multiple signatures on a bank transfer. However, some in the ecosystem have contested this framing, arguing that LayerZero’s default setup was to have 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 aftermath of the exploit has not been contained to Kelp, as its assets are utilized across multiple platforms, leading to a wider impact. '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 disparity between the marketing of decentralization and its actual implementation. 'A single verifier is not decentralized,' Schwed stated. 'It’s a centralized decentralized verifier.' Urbelis broadened this point, saying, '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 to be decentralized can have vulnerabilities, 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, critical but complex layers that move assets between systems or allow them to be reused. These layers, often beneath more visible applications and holding significant value, have become 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.