Octo2 Malware Uses Fake NordVPN, Chrome Apps to Infect Android Devices

Octo2 malware is targeting Android devices by disguising itself as popular apps like NordVPN and Google Chrome. This advanced trojan uses sophisticated techniques to evade detection, steal credentials, and enable remote access to infected devices.

Cybersecurity researchers at DomainTools have released their new research on Octo2, a new version of the notorious Octo malware family. Octo2 targets Android mobile devices and based on its activity, researchers believe that it will target users globally soon.

According to Steve Behm, Solutions Engineer at DomainTools, Octo2 represents a major change in cybersecurity threats. This updated version of the prolific Octo (ExobotCompact) family spreads rapidly due to its enhanced features, global adoption of its predecessor, and aggressive distribution tactics. 

Octo2 features improved remote access trojan capabilities, ensuring reliable communication and control over infected devices even in challenging network conditions. Moreover, its enhanced Anti-Analysis and Anti-Detection techniques can hinder security analysis and detection, making it more difficult to identify and neutralize the threat.

In addition, the use of DGA-Based C2 server generation algorithm (DGA) to create dynamic command and control (C2) server addresses adds a layer of complexity, making it harder for security systems to track and disrupt communication.

“We were eventually able to expand the original 9 domains and 7 TLDs to 269 domains and 12 TLDs first seen from August 22nd, 2024 to October 4th, 2024,” reads DomainTool’s blog post shared with Hackread.com ahead of publishing on October 10, 2024.

Currently Targeting Europe

Early samples of Octo2 have been observed in several European countries, including Italy, Poland, Moldova, and Hungary. However, given the global reach of the original Octo and the improvements in Octo2, its distribution is expected to expand rapidly. 

Attack Pattern – Disguised as VPN and Browser

The malware often disguises itself as legitimate applications, such as Google Chrome, NordVPN, or “Enterprise Europe Network,” to deceive unsuspecting users. It employs a dropper called Zombinder to deliver the malicious payload, prompting users to install a seemingly harmless plugin that is actually Octo2.   

For your information, Zombinder is another Android malware that was actively sold on the dark web in 2022. Its developers also offered a Windows version. At that time, Zombinder was found distributing the notorious Xenomorph banking malware, disguised as the VidMate app.

Once a device gets infected, Octo2 allows remote access to mobile devices, intercepting push notifications, harvesting credentials, and performing unauthorized actions, such as allowing for unauthorized login and access. The Conficker worm discovered in 2008 is one of the earliest examples of a DGA used by malware families and so far 50 malware families, including Zeus and Dyre, have been identified to be using DGA domains.

Abusing Domain Generation Algorithms

Octo2’s use of a DGA (Domain Generation Algorithms – Different from Registered Domain Generation Algorithms – RDGAs) to generate its C2 server address is a significant enhancement. This technique allows the malware to constantly change its communication endpoints, making it more resilient to takedowns and detection efforts. While researchers can identify the patterns used to generate these domains, the dynamic nature of the C2 infrastructure presents a massive threat.  

Domain Tools researchers warn users to be cautious of Octo2 malware and avoid downloading apps or software from third-party sites. For businesses, using threat intelligence is important. This includes advanced detection tools like sandboxing, monitoring DNS traffic for unusual activity, and using endpoint security solutions to spot malicious behaviour on infected devices. Regular DNS traffic monitoring can also help detect DGA-based malware.

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