Executive Summary

A new Malware-as-a-Service (MaaS) offering named 'Stanley' is being advertised on Russian-language cybercrime forums, providing a turnkey solution for criminals looking to conduct phishing and data theft campaigns. The service sells malicious Google Chrome extensions and, crucially, guarantees their successful publication on the official Chrome Web Store. This bypasses a major hurdle for attackers and leverages the trust users place in Google's official marketplace. The extensions are designed to spoof websites and steal user credentials. The 'Stanley' MaaS is indicative of the ongoing professionalization of cybercrime, where specialized services are packaged and sold, enabling a wider range of actors to deploy attacks.

Threat Overview

'Stanley' operates as a classic MaaS platform, abstracting the technical complexity of malware development and distribution away from the end-user (the criminal). By focusing on malicious browser extensions, the service targets a lucrative vector for credential theft.

• The Product: Malicious Google Chrome extensions.
• The Functionality: Primarily phishing. The extensions can likely inject fake login forms into legitimate websites, intercept form submissions, or redirect users to attacker-controlled phishing pages.
• The Key Selling Point: A guarantee of publication on the Chrome Web Store. This suggests the service operators have found a reliable method to bypass Google's automated and manual review processes, possibly by using obfuscation, delayed execution of malicious code, or other evasion techniques.

This model democratizes cybercrime, allowing actors with minimal technical skill to purchase and deploy a sophisticated attack tool.

Technical Analysis

While the exact techniques used by 'Stanley' extensions are not detailed, malicious browser extensions typically abuse the powerful permissions they are granted to compromise user security. Common techniques include:

• Content Script Injection (T1176): The extension injects malicious JavaScript into web pages the user visits. This script can be used to create fake login prompts, scrape data from the page, or hijack the user's session.
• Intercepting Network Requests: The extension uses its permissions to inspect, block, or modify the user's web traffic, allowing it to steal credentials as they are sent to a legitimate website.
• Credential API Access: Abusing the browser's credential management APIs to steal saved passwords.

To bypass the Chrome Web Store review, the 'Stanley' operators likely employ techniques such as:

• Remote Code Loading: The extension initially contains no malicious code, but later fetches and executes it from an attacker-controlled server.
• Time-Delayed Activation: The malicious functionality remains dormant for a period after installation to evade sandboxed analysis during the review process.
• Obfuscation: Heavily obfuscating the malicious code to make it unreadable to automated scanners and human reviewers.

Impact Assessment

• For Users: Users who install these extensions are at high risk of having their credentials for various online services (email, banking, social media) stolen. This can lead to financial loss, identity theft, and account takeovers.
• For the Ecosystem: The success of a service like 'Stanley' erodes trust in official marketplaces like the Chrome Web Store. It also increases the overall volume of phishing attacks, as more criminals are able to participate.

Detection & Response

• For Users:

  1. Be Wary of Extensions: Be highly critical of any browser extension you install. Read reviews carefully and question why an extension needs the permissions it requests.
  2. Monitor Permissions: Regularly review the permissions of your installed extensions. If a simple utility extension is asking for permission to read all data on all websites, it is a major red flag.
  3. Use Security Software: A comprehensive security suite may be able to detect and block the malicious activity of such extensions.

• For Organizations:

  1. Extension Allowlisting: Use enterprise policies (e.g., Google Workspace policies) to create an allowlist of approved Chrome extensions that employees can install. Deny all others by default.
  2. User Training: Train employees on the dangers of browser extensions and how to spot suspicious permission requests.

Mitigation

1. Principle of Least Privilege: When installing any software, including browser extensions, only grant the minimum permissions necessary for it to function.

2. Enterprise Extension Management: In a corporate environment, centrally manage and restrict which browser extensions can be installed on company devices. This is the most effective defense.

3. Regular Audits: Periodically audit the extensions installed on your personal and work browsers. Remove any that are no longer needed or that seem suspicious.