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 target the crypto trading firm Drift, another major exploit has been carried out, this time against Kelp, a restaking protocol connected to LayerZero's cross-chain infrastructure. This assault suggests an evolution in the tactics employed by North Korea-linked hackers, who are no longer just seeking out bugs or stolen credentials but are instead exploiting the fundamental assumptions underlying decentralized systems. The combined impact of these two incidents points to a more organized effort than a series of isolated hacks, as North Korea continues to escalate its attempts 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.' More than $500 million was stolen across the Drift and Kelp exploits in just over two weeks. 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 thereby approving transactions that never occurred. 'The security failure is simple: a signed lie is still a lie,' Urbelis noted. 'Signatures guarantee authorship; they do not guarantee truth.' This means the system checked who sent the message, not whether the message itself was correct. For security experts, this exploit highlights the issue of exploiting how the system was set up rather than discovering a new hack. David Schwed, COO of blockchain security firm SVRN, stated, 'This attack wasn’t about breaking cryptography; it was about exploiting how the system was set up.' A key issue was a configuration choice, with Kelp relying on a single verifier to approve cross-chain messages, a choice made for speed and simplicity but one that removes a critical safety layer. In the aftermath, LayerZero has recommended using multiple independent verifiers to approve transactions, akin to requiring multiple signatures on a bank transfer. However, some have pushed back on this, noting that LayerZero’s default setup was to have a single verifier. Schwed emphasized, '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 has not been limited to Kelp, as its assets are used across multiple platforms, meaning problems can spread quickly. 'These assets are a chain of IOUs,' Schwed said. '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 wider stress event. Lending platforms like Aave, which 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. 'A single verifier is not decentralized,' Schwed said. '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.' This means 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 can be explained by this shift, as they begin to focus on cross-chain and restaking infrastructure, the parts of crypto that move assets between systems or allow them to be reused. These layers are critical but complex and often 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. As attackers move faster, this gap is becoming both easier to exploit and far more expensive to ignore.