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

Less than three weeks after hackers linked to North Korea used social engineering to breach the crypto trading firm Drift, another major exploit was carried out, this time targeting Kelp, a restaking protocol connected to LayerZero's cross-chain infrastructure. This suggests an evolution in the tactics employed by North Korea-linked hackers, who are now exploiting fundamental assumptions built into decentralized systems, rather than just looking for vulnerabilities or stolen credentials. The combined impact of these two incidents points to a more organized effort by North Korea to intercept funds from the crypto sector, amounting to over $500 million stolen in just over two weeks. 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 but rather manipulating the data fed into the system, forcing it to rely on compromised inputs and approve 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.' This highlights a critical issue with the system's setup, particularly its reliance on a single verifier to approve cross-chain messages, which, although 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 have argued that LayerZero's default setup was to have a single verifier, with David Schwed, COO of blockchain security firm SVRN, stating, '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 ripple effect where problems can spread. 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, such as lending platforms like Aave that accepted the impacted assets as collateral and are now dealing with losses, turning a single exploit into a broader stress event. This incident also reveals 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, 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 that appear decentralized can have weak points, especially in less visible layers like data providers or infrastructure, which are increasingly the focus of attackers. The recent targeting by the Lazarus group, which has begun focusing on cross-chain and restaking infrastructure, underscores this shift. These layers are critical but complex, often underlying more visible applications, and they tend to hold large amounts of 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 but showed how exposed the ecosystem remains to familiar ones, especially when security is treated as a recommendation rather than a requirement. And as attackers move faster, this gap is becoming both easier to exploit and far more expensive to ignore.