On April 21, SlowMist Chief Information Security Officer 23pds warned that the Claude Desktop application was allegedly inserting a hidden backdoor file into user browsers without consent, intensifying concerns over AI-related software supply chain risks.
Hidden file in chromium-based browsers
According to the alert, the file is automatically written to all chromium-based browsers during installation of Claude Desktop.
The inserted file reportedly acts as a pre-authorized backdoor that, when combined with specific extensions, can enable full browser control. This could allow external parties to:
- Access browsing data
- Capture sensitive information
- Manipulate browser behavior without the user’s knowledge
Security researchers say the technique avoids overt permission requests or visible process changes, allowing operations to persist undetected for extended periods.
Part of a broader supply chain attack pattern
Security analysts describe the Claude Desktop case as fitting a familiar pattern of software supply chain exploitation, where attackers abuse trust in legitimate tools rather than relying on obviously malicious downloads.
Key traits of the current threat pattern include:
- Precise targeting of high-value data: crypto assets, privacy-related information, browser cookies, passwords, and digital wallet components
- Interference at multiple stages: development, distribution, or acquisition of software
- Use of trusted channels: phishing developer accounts, uploading harmful extensions disguised as legitimate, or buying reputable extensions and modifying them after purchase
In this instance, analysts say the installation workflow itself allegedly introduced code capable of silent execution, representing a variation on existing supply chain exploitation models.
AI tools as both attack vector and target
The incident highlights how integrated AI assistants and desktop tools are becoming deeply entangled with long-standing software supply risks.
Artificial intelligence platforms are now:
- A vector, when compromised to run malicious commands or code
- A target, as flaws in AI tooling can expose local files, browser data, and system-level resources
Documented cases such as the Claude Code privilege escalation flaw (CVE-2025-64755) have shown that misuse or exploitation of AI systems can lead to unintended access to local content and browser information.
Researchers warn that when AI systems gain direct control over computers or browsers, the margin for safe operation narrows sharply. Any exploited vulnerability can escalate from a single local weakness to full system exposure.
Severe extensions flaws and zero-click exploitation
Recent disclosures around the Claude ecosystem underscore how design choices in AI desktop architectures can magnify security impact.
- Zero-click remote code execution: Earlier this year, LayerX researchers uncovered a zero-click remote code execution vulnerability in Claude Desktop extensions that received a 10.0 CVSS score.
- A maliciously crafted Google Calendar event could trigger system takeover without further user interaction.
- The flaw reportedly affected more than 10,000 users.
- Lack of sandboxing: Unlike many browser-based plugins, Claude Desktop extensions often run outside a browser sandbox, with full access to the operating system.
- If compromised, an extension can potentially reach local files, stored credentials, and system commands, expanding the scope of any breach well beyond web activity.
- Command injection in official extensions: In November 2025, Koi Security reported critical command injection issues in three official extensions promoted by Anthropic for Chrome, iMessage, and Apple Notes.
- A malicious website could feed hidden instructions to the AI assistant.
- A normal user query could be turned into a command that executes hostile code, with the potential to steal session tokens, browser cookies, and SSH keys.
These findings underscore how subtle design decisions around permissions and isolation can convert convenience features into high-impact attack paths.
Malvertising and distribution-layer threats
Beyond core software and extensions, the surrounding ecosystem has also been targeted.
In March 2026, a malware campaign used Google Ads to redirect people searching for “install Claude Code” to a convincing clone of the official website. The counterfeit site then delivered malicious installation commands, demonstrating how:
- Paid ads can be abused to hijack traffic from users seeking legitimate AI tools
- Seemingly authentic download pages can be weaponized against those who follow typical “install from the official site” advice, if spoofing is successful
Direct risk to digital assets and browser integrity
For anyone managing cryptocurrency or other sensitive data on their machines, these developments show how browser and application integrity has become a central security concern.
Once an attacker gains control of the browser environment through a flawed extension or supply chain compromise, they can:
- Intercept or alter outgoing transactions
- Replace destination wallet addresses by changing clipboard contents at the moment of pasting
- Exfiltrate stored passwords, authentication cookies, or unencrypted private keys
- Monitor or alter web activity without visible indicators
Data from 2025 indicates that personal wallet compromises accounted for around $713 million in stolen funds, reflecting a shift toward targeting the user’s local environment instead of only centralized platforms.
At the same time, reports suggest software supply chain attacks doubled in 2025 compared with the previous year, with some analyses projecting global damage costs from such attacks reaching $60 billion by 2025.
Implications for trust in official software
Researchers view the Claude Desktop findings as part of a broader reassessment of what “official” and “trusted” software really mean in a supply chain context.
Key takeaways include:
- Trust in brand or origin alone is no longer sufficient, especially for tools with deep system integration or broad permissions
- AI-related products, due to their automation capabilities, can turn minor weaknesses into severe system-level threats
- Security models built around browser sandboxes and compartmentalization are strained when desktop AI extensions bypass these controls
The combination of AI autonomy, rich system access, and opaque installation processes raises the stakes for any security lapse.
Practical steps for higher-risk users
Those handling cryptocurrency, corporate credentials, or other sensitive information are being urged to adopt a more skeptical stance toward installations and permissions, particularly for AI assistants and their extensions.
Recommended practices include:
- Tighten application permissions
- Review permissions for all installed applications and browser extensions.
- Disable or remove components that are non-essential or not from a fully trusted and verified source.
- Limit extension footprint
- Keep only a minimal set of extensions, particularly in browsers used for financial operations or access to sensitive accounts.
- Avoid installing experimental or newly released extensions on systems that hold digital wallets or keys.
- Harden installation sources
- Download software only from the confirmed official developer domain, navigating manually rather than via ads or search results where feasible.
- Treat sponsored links and third-party repositories as high-risk, even if they appear legitimate.
- Audit AI-generated code and outputs
- Review any AI-generated scripts or commands before running them, especially those that touch file systems, shells, or package managers.
- Segment environments so that experimental AI code is not executed on machines holding production keys or wallets.
- Separate critical activities
- Use dedicated browsers or profiles for crypto and sensitive work, with minimal or no extensions.
- Consider air-gapped or hardware-based solutions for storing long-term private keys.
As AI-powered assistants become more deeply embedded in operating systems and browsers, the line between productivity tool and potential attack vector continues to blur, forcing traders and security teams alike to raise their scrutiny of even the most familiar applications.
Concerned about AI security and hidden backdoors? Learn how exchanges safeguard users in our security guide today.
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