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 significant exploit has been attributed to them, 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, shifting from exploiting bugs or stolen credentials to manipulating the foundational assumptions of decentralized systems. The combined impact of these incidents points to a more organized effort by North Korea to siphon funds from the crypto 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 siphoned across the Drift and Kelp exploits in just over two weeks, highlighting the scale of the issue. The Kelp breach did not involve breaking encryption or cracking keys; instead, attackers manipulated the data input into the system, forcing it to rely on compromised inputs and thus approving transactions that never occurred. Urbelis noted, 'The security failure is simple: a signed lie is still a lie. Signatures guarantee authorship; they do not guarantee truth.' This exploit underscores a basic security flaw where the system checked the sender's identity but not the truthfulness of the message itself. 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. In response, 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, stating 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 impact of the exploit has not been limited to Kelp, as its assets are used across multiple platforms, leading to a wider stress event. Lending platforms like Aave, which accepted the impacted assets as collateral, are now dealing with losses. The incident also highlights a gap between the marketing of decentralization and its actual implementation. Schwed pointed out, 'A single verifier is not decentralized; it’s a centralized decentralized verifier.' Urbelis further emphasized, '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 that even seemingly decentralized systems 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 for moving assets between systems or allowing them to be reused but are complex and often under visible applications, making them attractive targets due to the large amounts of value they hold. 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.