North Korean State Hackers Exposed in JumpCloud Attack: A Deep Dive into UNC4899 and Their Modus Operandi

In a significant cybersecurity development, the recent JumpCloud hack has been attributed to North Korean nation-state actors affiliated with the Reconnaissance General Bureau (RGB). This attribution comes following an operational security (OPSEC) blunder that exposed their actual IP address. This article delves into the details of this sophisticated attack and explores the tactics, techniques, and procedures (TTPs) employed by the threat actor group UNC4899.

Identification of Threat Actor UNC4899

Mandiant, a prominent cybersecurity firm, has attributed the activity to a threat actor it tracks under the name UNC4899. This group likely shares overlaps with clusters already being monitored as Jade Sleet and TraderTraitor. UNC4899 has built a reputation for targeting the blockchain and cryptocurrency sectors, displaying a history of attacks that aim to compromise these industries.

Overlap with APT43 Hacking Crew

UNC4899 also overlaps with APT43, another hacking crew associated with the Democratic People’s Republic of Korea (DPRK). Earlier this year, APT43 was unmasked as conducting a series of campaigns aimed at gathering intelligence and siphoning cryptocurrency from targeted companies. The connection between UNC4899 and APT43 further substantiates North Korea’s active involvement in cyber espionage and financial theft.

Modus Operandi of the Adversarial Collective

The Adversarial Collective, including UNC4899 and APT43, employs a sophisticated modus operandi to conceal their origins and evade detection. They utilize Operational Relay Boxes (ORBs) along with L2TP IPsec tunnels and commercial VPN providers to disguise their true point of origin. Commercial VPN services act as the final hop in their attack chain, making it extremely challenging to trace their activities back to North Korea.

Details of the JumpCloud Intrusion

The intrusion against JumpCloud took place on June 22, 2023, as part of a highly targeted spear-phishing campaign. The attackers successfully leveraged unauthorized access to breach fewer than five customers and compromised less than 10 systems. This attack was executed through a software supply chain attack, underscoring the sophistication and careful planning of the threat actors.

Incident Response and Mandiant’s Findings

Mandiant’s investigation into the JumpCloud attack was initiated after a cyber attack against one of JumpCloud’s affected customers, an undisclosed software solutions entity. The investigation uncovered a malicious Ruby script named “init.rb,” which was executed via the JumpCloud agent on June 27, 2023. The targeting of four Apple systems running macOS Ventura versions 13.3 or 13.4.1 underscores the ongoing efforts by North Korean actors to develop malware specifically designed for the Apple ecosystem.

Initial Access and Insertion of Malicious Code

The attackers gained initial access by compromising JumpCloud and inserting malicious code into their command framework. In at least one instance, the malicious code was a lightweight Ruby script executed via the JumpCloud agent. This foothold allowed the adversaries to move laterally within the network and execute their sophisticated attack chain.

Second-Stage Payload and Deployment of Additional Malware

The malicious script, “init.rb,” was engineered to download and execute a second-stage payload called FULLHOUSE.DOORED. This payload acted as a conduit to deploy additional malware, including STRATOFEAR and TIEDYE. After the deployment of these payloads, the threat actors meticulously removed traces of their activities to cover their tracks and avoid detection.

Financial Motivation of DPRK Actors

Both UNC4899 and APT43 have suspected ties to financially motivated DPRK actors. This suggests that North Korean operators are actively implementing supply chain attacks as a means to generate illicit financial gains. The targeting of the blockchain and cryptocurrency sectors aligns with the regime’s ongoing interest in exploiting these lucrative industries.

The attribution of the JumpCloud hack to North Korean state hackers highlights the ongoing cyber threat posed by the DPRK. The use of sophisticated tactics, techniques, and procedures (TTPs), connections to other hacking groups, and the ongoing development of customized malware for specific platforms demonstrate the extent of their capabilities. It is crucial for organizations to strengthen their cybersecurity measures to defend against targeted attacks like these and safeguard sensitive data and assets.

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