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

Less than three weeks after North Korea-linked hackers used social engineering to breach crypto trading firm Drift, hackers with ties to the nation have carried out another significant exploit, this time 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 built into decentralized systems. The combined incidents of the Drift and Kelp exploits, which together resulted in the theft of over $500 million in just over two weeks, point to a more organized effort by North Korea to hijack 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 feeding into the system, forcing it to rely on compromised inputs and approve transactions that did not actually occur. As Urbelis noted, 'The security failure is simple: a signed lie is still a lie. Signatures guarantee authorship; they do not guarantee truth.' This exploit highlights a critical issue with the system's configuration, particularly its reliance on a single verifier to approve cross-chain messages, which, while faster and simpler to set up, removes a crucial 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 pushed back against this recommendation, arguing that LayerZero's default setup was to use a single verifier. David Schwed, COO of blockchain security firm SVRN, emphasized that '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 Kelp exploit has not been limited to Kelp itself; due to the interconnected nature of DeFi systems, problems can spread quickly. As Schwed explained, 'These assets are a chain of IOUs. 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. In this case, lending platforms like Aave that accepted the impacted assets as collateral are now dealing with losses. The attack also exposes a gap between the marketing of decentralization and its actual implementation. As Schwed pointed out, 'A single verifier is not decentralized. 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 that appear decentralized can have weak points, particularly in less visible layers like 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, often sitting beneath more visible applications, and they tend to hold large amounts of 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; instead, 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.