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

Barely three weeks after hackers linked to North Korea used social engineering to breach the crypto trading firm Drift, another significant exploit has been carried out, 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 no longer just exploiting bugs or using stolen credentials but are now manipulating the fundamental assumptions underlying decentralized systems. The combined impact of these incidents suggests 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 fed into the system, forcing it to rely on compromised inputs and approve non-existent transactions. As Urbelis noted, 'The security failure is simple: a signed lie is still a lie. Signatures guarantee authorship; they do not guarantee truth.' In simpler terms, the system verified the sender of the message but not the message's accuracy. For security experts, this exploit highlights the manipulation of the system's setup rather than the introduction 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 the configuration choice of relying on a single verifier to approve cross-chain messages, which, although faster and simpler to set up, removes a critical safety layer. Following the incident, 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, stating 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 fallout from the exploit has not been contained to Kelp, as its assets are utilized across multiple platforms, leading to a broader stress event. '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, resulting in lending platforms like Aave, which accepted the impacted assets as collateral, now facing losses. This exploit also exposes a disparity 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 expanded on this, 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, 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 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 reveal a new type of weakness; instead, it demonstrated how exposed the ecosystem remains to familiar vulnerabilities, especially when security is treated as a recommendation rather than a requirement. As attackers accelerate their efforts, this gap is becoming both easier to exploit and more expensive to ignore.