Thursday September 18, 2025

HOOK ANDROID BANKING TROJAN WITH RANSOMWARE AND SPYWARE CAPABILITIES

Advisory ID: NCC-CSIRT-2025-014

Summary: 

A sophisticated and dangerous Android banking trojan, known as "Hook," is being actively distributed to target users of banking, financial, and cryptocurrency applications. Hook is designed to steal credentials and Personally Identifiable Information (PII) through overlay attacks and has evolved to include capabilities for full remote device takeover, data exfiltration, and ransomware-like features. The primary infection vector is social engineering, tricking users into installing malicious applications from unofficial sources. 

Damage/Probability: High/Critical

Product(s): 

Android Mobile Devices and Applications (Banking, Financial, and Cryptocurrency Apps)

Version(s): 

All versions of Android OS (targeted via malicious apps) 

Platform(s): 

Android OS

Description: 

The Hook trojan operates by masquerading as a legitimate application, such as a utility tool, system update, or a popular app. Once installed, it persistently requests the user to grant it powerful permissions, specifically targeting Android's Accessibility Services.

Upon receiving these permissions, Hook gains the ability to:

  • Perform Overlay Attacks: When a user opens a targeted banking or financial app, Hook displays a fake, identical-looking login screen over the real app. The user unknowingly enters their credentials into this malicious window, which are then captured and sent to the attacker's server.
  • Act as a Remote Access Tool (RAT): Attackers can establish a remote connection to the infected device, view the screen in real-time, simulate screen taps, log keystrokes, and navigate the device's user interface.
  • Intercept Communications: The malware can read SMS messages, allowing it to bypass Two-Factor Authentication (2FA) codes sent via text.
  • Exfiltrate Files: Hook can browse the device's file system and steal sensitive documents, photos, and other personal data.

Impacts: 

A successful infection by the Hook trojan can lead to severe consequences, including:

  • Direct Financial Loss: Unauthorized access to bank accounts, leading to theft of funds.
  • Data Breach: Theft of sensitive personal information, including login credentials for multiple services, contacts, and private files.
  • Identity Theft: The stolen information can be used to impersonate the victim and open fraudulent accounts.
  • Complete Device Compromise: Attackers can gain full control over the device, using it for further malicious activities.
  • Ransomware Attack: The trojan can lock the device's screen and demand a ransom payment for its release.

Solutions: 

All Android users are strongly advised to adopt the following security measures to protect against this threat:

Immediate User Actions:

  • Restrict App Sources: Only install applications from the official Google Play Store. Disable the "Install from unknown sources" option in your Android settings.
  • Scrutinize Permissions: Be extremely cautious of any application requesting Accessibility Service permissions. These permissions grant extensive control over your device and should only be given to fully trusted applications from reputable developers.
  • Enable Google Play Protect: Ensure this built-in security feature is active on your device.
  • Update Regularly: Keep your Android operating system and all installed applications updated to the latest versions to ensure you have the most recent security patches.
  • Practice Phishing Awareness: Do not click on suspicious links or download attachments from unknown senders in emails, SMS, or messaging apps.
  • Use a Mobile Security Solution: Install a reputable antivirus or anti-malware application from a known security vendor.

If an Infection is Suspected:

  1. Immediately disconnect the device from all networks (Wi-Fi and Mobile Data).
  2. Boot the device into Safe Mode to prevent third-party apps from running and attempt to uninstall the malicious application.
  3. If the malicious app cannot be removed, a full factory reset is the most reliable method to ensure the malware is completely eradicated. Note that this will erase all data on the device.
  4. After securing your device, immediately change the passwords for your banking, email, and other critical online accounts from a separate, trusted device.

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