← 목록

Superior: Crypto and Credential Theft via Browser Extension Acquisition and Malicious Updates

devto 2026-08-31 원문 보기 ↗


1. Basic Information

2. Executive Summary

Threat actors published custom or acquired Chrome and Edge extensions in a harmless state to build a user base before pushing malicious updates. After the update, the extensions received encrypted JavaScript modules from a command and control (C2) server, stripped Content Security Policy (CSP) headers from web pages, stole cryptocurrency wallets, credentials, session data, and browsing history, and displayed ClickFix-style fake update prompts.

3. Attack Flow

Distribution via Abused Extension Trust

  1. Threat actors publish a harmless extension with practical features or acquire an existing extension with an established user base from its original author.
  2. Users install the extension, and the browser automatically updates it to newer versions by default.
  3. Threat actors publish a new version containing malicious code and distribute it to existing users. The change in extension ownership is not explicitly notified to users.

Module Retrieval and In-Page Execution

  1. The background service worker generates a unique installation UUID and establishes a WebSocket connection with the C2 server.
  2. The extension stores the JavaScript modules received from the C2 server in chrome.storage.local encrypted with AES-GCM, using a key derived from the extension ID and installation UUID.
  3. The extension registers dynamic declarativeNetRequest rules to strip Content-Security-Policy response headers from browsed pages.
  4. Content scripts set the malicious code as an event handler on a hidden DOM element, trigger the event, and execute the code in the main world of the web page.
  5. Depending on the target site and user activity, the extension intercepts wallet operations, steals recovery phrases, obtains credentials and session tokens, transmits browsing history, or initiates ClickFix redirection.

4. Threat Actor Positioning and Execution Locations

5. Visibility for Victims and Administrators

Victims

Administrators

6. Success and Failure Conditions

Success Conditions

Failure Conditions / Risk Mitigation

7. What Happens Upon Successful Exploitation

8. Observable Logs

9. Attack Success Assessment

10. Investigation Playbook

11. Defense and Detection Ideas

12. Facts / Inference / Hypothesis

Facts

Hypothesis and Inferences

13. MITRE ATT&CK Mapping

14. Unknowns and Additional Investigations

15. Impact on SOCs and Organizations

Organizations that leave Chrome and Edge extension management to users cannot rely on official stores and historical reputation alone to ensure security. Particularly on devices handling cryptocurrency, finance, administrative consoles, and recruitment or sales social media, organizations must conduct urgent inventories of known IDs, enforce allowlist policies, monitor changes to ownership, permissions, and versions, visualize WebSockets, and control shell execution originating from browsers.

16. Summary by Target Audience