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Writer's pictureFrancis Borges

CovertCatch Malware: North Korean Hackers Using Linkedin for spreading Rustbucket Malware

Updated: Sep 17

North Korean threat actors have been detected using LinkedIn to target developers through bogus job recruiting schemes. Utilizing "coding tests" as an entry point for their attacks, these cybercriminals are deploying CovertCatch, a new strain of malware disguised as a Python coding challenge. This revelation comes from a recent in-depth report by Mandiant, a Google-owned cybersecurity firm, which sheds light on threats faced by the burgeoning Web3 industry.



North Korean Hacker


The Mechanics of CovertCatch


According to Mandiant researchers, the attack unfolds through an elaborate social engineering campaign:


  1. Initial Contact and Engagement: The attackers initiate a conversation on LinkedIn, posing as recruiters offering lucrative job opportunities. Following an initial chat and gaining the target's trust, they send a ZIP file under the pretense of a "coding challenge".


  2. Malicious Payload: The ZIP file contains the CovertCatch malware hidden as a Python coding test. When the unsuspecting recipient opens it, the malware is activated, setting the stage for the next steps of compromise.


  3. System Compromise: CovertCatch serves as a launchpad for the secondary payload, a piece of malware known as Rustbucket. This payload establishes persistence on the victim’s system by using Launch Agents and Launch Daemons, ensuring the malware remains operational even after a system reboot. This malware also acts as a data harvesting tool, allowing the hackers to exfiltrate data from the target machine.



A Broader Campaign Strategy


The exploitation of job-related decoys isn’t a new tactic for North Korean hacking groups. This method forms part of broader campaigns such as Operation Dream Job and Contagious Interview, where recruiting themes are used to gain trust of individuals and infiltrate systems.


In addition, these techniques have been linked to malware families like RustBucket and KANDYKORN. For example, in one incident reported by Mandiant, a malicious PDF masquerading as a job description for a "VP of Finance and Operations" at a prominent cryptocurrency exchange was used to drop RustBucket malware.


North Korean Rustbucket Malware

The Functionality and Impact of the RustBucket Malware


RustBucket, a backdoor written in the Rust programming language, is designed to:


- System Reconnaissance: Collect basic system information and communicate with a command-and-control (C2) server via a hard-coded URL.

- Persistence: It establishes persistence by disguising itself as a "Safari Update," ensuring it remains active on the system.


Through these sophisticated techniques, North Korean hackers gain a broad foothold, leveraging this access to conduct extensive reconnaissance, steal credentials, and perpetrate further attacks on targeted organizations.



Expanding Beyond Social Engineering: Supply Chain Attacks


Cybersecurity experts have observed that North Korea’s targets within the Web3 landscape go beyond social engineering, extending to software supply chain attacks. Notable incidents include attacks on 3CX and JumpCloud in 2023, where the attackers successfully infiltrated these platforms, affecting numerous users downstream.



FBI's Warning and Impersonation Tactics


Highlighting the severity of this threat, the FBI has issued warnings about tailored social engineering campaigns targeting the cryptocurrency industry. These operations frequently impersonate recruiting firms or familiar contacts, crafting highly personalized fake scenarios to increase their success rate.


The FBI notes that these threat actors conduct thorough pre-operational OSINT (Open Source Intelligence) research, referencing personal details, professional connections, or specific interests in their communications to build rapport. By creating a facade of legitimacy, they aim to lure victims into complacency before delivering malware.



Protecting Yourself and Your Organization


Given the elaborate nature of these attacks, here are some crucial steps to safeguard against such threats:


  1. Education and Awareness: Regularly educate staff about the risks of unsolicited job offers on professional networks.


  2. Verification Protocols: Implement stringent verification of unexpected job offers received online. This is especially important for those who may be down on their luck and desperately searching for a job, as these people may be quicker to engage with these hackers who are promising employment.


  3. Advanced Security Solutions: Deploy advanced security measures, including endpoint protection and network monitoring, to catch suspicious behavior.


  4. Regular Security Audits: Perform regular audits and updates to ensure all systems and software are secure and up-to-date.



Conclusion


The aggressive tactics employed by North Korean threat actors underscore the persistent and evolving nature of cyber threats. Their exploitation of trusted platforms like LinkedIn emphasizes the need for constant vigilance and robust online practices. Stay Safe!




Francis Borges










Francis Borges


Founder / Security Engineer

Dynacomp IT Solutions

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