Mobile banking trojans are evolving, and Hook v3 is a stark reminder of how sophisticated and dangerous these threats are becoming. Zimperium's zLabs research sheds light on just how advanced these attacks have grown, and what security professionals need to know to defend against them.
According to Zimperium's blog post, Hook Version 3 isn't your average banking trojan; it's packed with advanced features that make it one of the most formidable threats yet. The malware leverages multiple attack vectors, including overlays, phishing lures, real-time screen streaming, and distribution via GitHub, all supported by more than 100 remote commands.
This level of capability places Hook v3 at the cutting edge of mobile threat development.
Hook v3's sophistication aligns with a broader trend Zimperium highlights across its Mobile Banking Heists Report. Their 2023 findings show that 29 malware families targeted 1,800 banking apps across 61 countries—a stark increase from the previous year's figures. Notably, Hook was named among the most prevalent families, alongside GodFather and Teabot.
These families are not static threats: the report documents 10 newly discovered families and enhanced capabilities across the board—such as automated fund transfers, screen sharing, Telephone-based Attack Delivery (TOAD), and Malware-as-a-Service (MaaS) offerings.
Hook v3 exemplifies several striking trends:
Overlay and phishing techniques: By showing fake login screens, the trojan collects credentials effortlessly.
Screen streaming and remote control: These features enable real-time surveillance and manipulation, increasingly blurring the line between user and attacker control.
GitHub distribution: Leveraging a trusted platform for distribution boosts both credibility and reach.
Extensive remote command set (100+ commands): Provides granular control and enhanced automation for the attacker.
These advancements extend the reach and stealth of financial fraud, outperforming earlier generations that relied more heavily on simpler overlays or fake forms.
Nico Chiaraviglio, Chief Scientist at Zimperium, broke down the findings into three key areas.
1. Evolution into a hybrid: impact on mobile security mindset
"Hook v3 fuses ransomware, spyware, and banking malware functions into a single, highly modular trojan, effectively breaking down traditional threat category boundaries. Its new capabilities include full-screen ransomware overlays, fake NFC prompts, lock-screen bypass with deceptive PIN/pattern capture, transparent gesture-capturing overlays, and stealthy real-time screen streaming—all enabled via 107 remote commands.
Implications:
Multi-vector risk: Businesses and individuals can no longer compartmentalize threats—one infection can encompass financial theft, espionage, and extortion simultaneously.
Blurred lines between malware classes: Traditional defenses built for a single threat type may fail; organizations must adopt cross-category detection. This is pretty common in some industries and could expose end users or enterprises to significant risks.
Emphasis on proactive, on-device detection: Offline, real-time defenses (like on-device runtime protection) are essential to catch fast, stealthy, UI-level manipulations.
Elevated vigilance around legitimate-seeming triggers: Overlays mimic usable UI—requiring dynamic, behavior-based detection beyond signature matching.
2. GitHub distribution: risks even in trusted channels
Hook v3 is being distributed not just via phishing websites but also through GitHub repositories hosting malicious APKs (both Hook and Ermac variants), along with other malware like Brokewell and SMS spyware.
Enterprise takeaways:
Trusted doesn't mean safe: Platforms like GitHub can be weaponized; open-source assumptions must be reconsidered. Moreover, attackers are weaponising these platforms knowing enterprises trust them.
Need for stringent inbound code/app vetting: Even if an APK originates from GitHub, it must undergo rigorous security checks before approval or installation.
Policy and technical enforcement: Enterprises must enforce policies (e.g., disabling sideloading), utilize Mobile Threat Defense (MTD), and apply Mobile Application Vetting to block malicious overlays or hidden payloads.
3. Protecting financial institutions from Hook v3's advanced abilities
Hook v3's capabilities, screen streaming, credential harvesting, UI interaction, lock-screen bypasses, and overlays for phishing pose a direct threat to sensitive data flows and customer trust.
Strategic priorities:
Deploy on-device Mobile Threat Defense (MTD).
Leverage runtime protection to catch overlay and gesture-based attacks as they occur.
Harden banking and finance mobile apps to resist UI hooks, overlay injection, and accessibility abuse—through techniques like tamper detection, and runtime integrity checks.
Robust access controls and app vetting: Use strong authentication (e.g., MFA not reliant on SMS/overlay), vet all app installations (including BYOD scenarios), and restrict the use of accessibility services to trusted apps only.
User education and behavior monitoring: Train users to recognize signs of ransomware overlays, fake UI, and unexpected prompts. Pair with real-time analytics to flag atypical device activity.
Assume device compromise is possible, and mitigate via segmentation, least-privilege access, data encryption, and continuous validation, even before trusting device input."
The report offers strategic takeaways for cybersecurity teams.
Zimperium’s insights into Hook v3 make one thing clear: mobile banking malware continues to escalate in complexity and impact. With remote control, overlay deception, and evasive distribution methods, these threats are smarter and more dangerous than ever.
To remain resilient, security teams must adopt:
Proactive, on-device defenses
Real-time visibility into app and device behavior
Threat intelligence aligned with rapidly evolving attack vectors
A broad security posture that extends beyond banking to all mobile workflows
For more insights on this topic, attend the SecureWorld Financial Services virtual conference on September 25, 2025. See the agenda and register here.