The Lazarus hacking group from North Korea is reported to have reverted to an old tactic to launder $23 million obtained during an attack in November. According to investigators at Elliptic, a blockchain research company, the funds, which were part of the $112.5 million stolen from the HTX cryptocurrency exchange, have been laundered through the Tornado Cash mixing service.

Elliptic highlighted the significance of this move, noting that Lazarus had previously switched to Sinbad.io after U.S. authorities sanctioned Tornado Cash in August 2022. However, Sinbad.io was later sanctioned in November. Elliptic observed that Lazarus Group appears to have resumed using Tornado Cash to obscure the trail of their transactions, with over $23 million laundered through approximately 60 transactions.

The researchers explained that this shift in behavior likely stems from the limited availability of large-scale mixers following law enforcement actions against services like Sinbad.io and Blender.io. Despite being sanctioned, Tornado Cash continues to operate due to its decentralized nature, making it immune to seizure and shutdown like centralized mixers.

Elliptic has been monitoring the movement of the stolen $112.5 million since HTX attributed the incident to Lazarus. The funds remained dormant until March 13 when they were observed passing through Tornado Cash, corroborated by other blockchain security firms.

North Korean hackers utilize services such as Tornado Cash and Sinbad.io to conceal the origins of their ill-gotten gains and convert them into usable currency, aiding the regime in circumventing international sanctions related to its weapons programs, as per U.S. government claims.

According to the U.S. Treasury Department, North Korean hackers have utilized Sinbad and its precursor Blender.io to launder a portion of the $100 million stolen from Atomic Wallet customers in June, as well as substantial amounts from high-profile crypto thefts like those from Axie Infinity and Horizon Bridge.

Researchers estimate that North Korean groups pilfered around $1.7 billion worth of cryptocurrency in 2022 and approximately $1 billion in 2023. The Lazarus Group, operational for over a decade, has reportedly stolen over $2 billion worth of cryptocurrency to finance North Korea's governmental activities, including its weapons programs, as stated by U.S. officials. The group itself faced U.S. sanctions in 2019.