Lemon Duck

Researchers from Cisco Talos have recently detected a Lemon Duck Cryptocurrency that is targetting different businesses within sectors like the government, retail, and technology.

The attacker uses various techniques to spread the malware all over the network, just as sending affected RTF files by using email, psexec, WMI, and SMB exploits. Moreover, these files also contain the infamous Eternal Blue and SMBGhost threats that affect the Windows 10 machines. 

Some variants also support RDP brute-forcing, and experts have identified that the attackers also use tools such as Mimikatz, as it helps the botnet increase the number of systems participating in its opening pool.

Lemon Duck

Lemon Duck is a botnet that has automatic spreading capabilities. Its concluding payload is a modification of the Monero cryptocurrency mining software XMR. Lemon Duck is one of the most complicated mining botnets with various impressive methods and techniques to cover up all its operations.

According to the reports, the security experts have recently seen a recovery in the number of DNS requests that are connected with its command and control and mining servers.

That’s why the security experts have decided to take a close look at its functionality by prioritizing previously less documented modules like the Linux branch and C# modules that are loaded by the specific PowerShell component.

This threat has been active since the end of December 2018, and there has been an apparent increase in its activity at the end of August 2020.

Infection vectors

According to the Cisco Talos report, Researchers recorded 12 independent infection vectors ranging from standard copying over SMB shares and tried to use the vulnerabilities in Redis and the YARN Hadoop resource manager and job scheduler. 

Not only this, but the Talos experts have also noticed a huge increase in the number of DNS requests connected with Lemon Duck C2 and mining servers, and it has been done at the end of August 2020.

GPUs used by Lemon Duck for mining

  • GTX
  • AMD

Modular Functionalities

In Lemon Duck, the modules that are included are the primary loader; it checks the level of user privileges and all the elements that are relevant for mining, like the type of the accessible graphic card. If these GPUs are not identified, then the loader will get download and run the commodity XMRig CPU-based mining script.

Moreover, other modules are included in the main spreading module, a Python-based module packaged using a Pyinstaller, and a killer module designed to impair known competing mining botnets.

Open-source PowerShell projects code included in Lemon Duck

  • Invoke-TheHash by Kevin Robertson
  • Invoke-EternalBlue PowerShell EternalBlue port
  • BlueKeep RCE exploit (CVE- 2019-0708) PowerShell port
  • Powersploit’s reflective loader by Matt Graeber
  • Modified Invoke-Mimikatz PowerShell module

Apart from this, the threat actors behind Lemon Duck want to make sure that their operation must be profitable. That’s why the Lemon Duck has checked all the infected machines for other known crypto miners and shuts them down accordingly.

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BALAJI is an Ex-Security Researcher (Threat Research Labs) at Comodo Cybersecurity. Editor-in-Chief & Co-Founder - Cyber Security News & GBHackers On Security.