New Medusa RAT Attacking Android Devices to Steal SMS & Screen Controls

A new variant of the Medusa malware family was discovered disguised as a “4K Sports” app, which exhibits changes in command structure and capabilities compared to previous versions. 

Researchers believe these changes are aimed at improving efficiency and strengthening the botnet.

The MaaS model used by Medusa allows for adaptations based on various factors, such as new affiliates seeking less detectable variants to target unexplored regions. 

The Medusa banking Trojan, first discovered in 2020, grants attackers remote access to devices through VNC and accessibility services, allowing them to perform real-time screen sharing, steal keystrokes, and launch overlay attacks for on-device fraud (ODF) such as account takeover (ATO). 

Medusa communicates with the attacker’s C2 server through a web socket connection, fetching the URL dynamically from social media platforms like Telegram for obfuscation and resilience against takedowns.

The malware also utilizes backup channels on social media for additional communication redundancy. 

A recent resurgence of Medusa malware campaigns, since July 2023, utilizes social engineering (smishing) to deliver droppers that side-load the malware onto Android devices in targeted countries (CA, ES, FR, IT, UK, US, TK). 

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This new variant leverages on-device fraud (ODF) but specific cash-out methods and transfer amounts remain unknown, while Medusa exhibits adaptability through its backend infrastructure, which can support multiple botnets with distinct functionalities. 

Cleafy discovered five active botnets that were distinguished from one another based on the types of decoys, distribution strategies, and locations that were targeted. 

Two Medusa botnet clusters were identified; where Cluster 1 targets Turkey, the US, and Canada and uses traditional phishing tactics, while Cluster 2 targets Europe and uses droppers besides phishing, as both clusters are reducing requested permissions to evade detection. 

Early campaigns requested permissions for cameras, microphones, locations, etc., but recent campaigns only request permissions for core functionalities like accessibility, SMS, internet, foreground service, and package management, which makes them stealthier and harder to detect.  

Researchers identified a new variant of Medusa malware with a streamlined command set, and 17 commands from the previous version were removed to reduce its footprint and improve stealth. 

Five new commands were introduced, including taking screenshots, uninstalling apps, and controlling the device screen with a black overlay, which allows attackers to mask malicious activities and potentially steal sensitive information. 

Some functionalities requiring permissions (e.g., sending SMS, getting contacts) are still present in the code but blocked by the system without permission grants, which suggests that the malware is adaptable and can be easily modified for future campaigns. 

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