Mozilla Firefox add-on ecosystem has recently become the target of a sophisticated and dangerous attack. Over 40 fake cryptocurrency wallet extensions were discovered in the Firefox Add-ons Store, mimicking popular digital wallets such as Ledger, MetaMask, Trezor, and Rabby.
These malicious add-ons are designed with one purpose – to steal users’ seed phrases and drain their crypto holdings. Although Mozilla has since removed the fraudulent extensions, this event highlights an alarming trend in cybercrime where attackers abuse trusted browser environments to launch highly targeted scams.
The Attack Methodology
The fraudulent extensions imitated legitimate wallet interfaces, tricking users into entering sensitive credentials like seed phrases, private keys, and recovery passphrases. Once entered, these credentials were transmitted to attacker-controlled servers, giving cybercriminals complete access to the victims’ crypto assets.
Because these add-ons were published in an official browser store, many users mistakenly trusted them without verifying authenticity — a classic example of trust exploitation. Worse, the extensions were found to remain functional across browser restarts, increasing the likelihood of long-term data exfiltration and theft.
What Makes This Threat So Concerning
This incident is not just about individual users losing crypto; it’s a broader warning to organizations that allow employees to install browser extensions, use crypto wallets, or engage with DeFi applications on workstations or unmanaged devices.
The risks include:
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Credential theft leading to financial loss or insider trading liabilities
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Unregulated extensions introducing malware or backdoors
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Browser-based data leakage impacting enterprise systems
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Targeted phishing based on stolen metadata or login histories
As crypto adoption grows among enterprises – from fintech to investment firms to tech companies – malicious browser-based tools represent a new and dangerous threat vector.
Recommendations for Organizations
At COE Security, we advise security teams to take the following steps:
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Restrict browser extension installations through group policy or enterprise mobility management (EMM) tools.
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Whitelist only vetted wallet apps and browser extensions approved by your IT or security team.
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Regularly audit browser environments for unauthorized or suspicious add-ons.
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Deploy browser isolation and hardening policies, especially on devices with crypto access.
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Educate employees and clients about verifying wallet tools and avoiding seed phrase reuse.
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Monitor DNS and network traffic for indicators of command-and-control connections or unauthorized data exfiltration.
Conclusion
The rise of fake wallet extensions is yet another example of how cybercriminals are adapting faster than many enterprise defenses. Browser ecosystems are now legitimate attack surfaces – and organizations must treat them as such. Relying on the security of app stores or default browser warnings is no longer enough. Proactive controls, awareness, and governance are critical to securing digital assets and user trust.
About COE Security
COE Security empowers organizations to defend against evolving cyber threats through proactive, customized, and regulation-ready cybersecurity services. We support industries like:
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Financial services and crypto trading platforms
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Technology and fintech innovators
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Legal firms handling digital asset transactions
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eCommerce platforms with integrated crypto payments
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Government and regulators enforcing crypto compliance
We specialize in:
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Browser security hardening and zero trust endpoint management
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Threat hunting and malware analysis
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Crypto wallet and digital asset risk assessments
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Compliance with GDPR, ISO 27001, NIST, SEC, and FINRA guidelines
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Penetration testing and red teaming simulations
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Security awareness and phishing resilience training
COE Security transforms security challenges into strategic advantages – helping businesses stay safe, compliant, and competitive in the digital age.
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