Browser Extensions

Browser Extensions [T1176]

Information

• Name: Browser Extensions

• ID: T1176

• Tactics: TA0003

Introduction

Browser extensions, as defined within the MITRE ATT&CK framework (Technique ID: T1176), represent a tactic where adversaries exploit or manipulate browser extensions to execute malicious activities. Browser extensions are small software modules designed to enhance browser functionality, but attackers can leverage them to achieve persistence, execute arbitrary scripts, collect sensitive information, or redirect user traffic. Due to their integration into browsers, compromised or malicious extensions can provide adversaries significant access to user data and browser behavior.

Deep Dive Into Technique

Browser extensions typically operate within the browser's context, granting them extensive access to web page content, user interactions, cookies, browsing history, and network requests. Attackers exploit extensions through several technical methods:

• Malicious Extension Development:

  • Attackers create extensions that appear legitimate but contain hidden malicious functionality.

  • These extensions may pass initial browser store security checks through obfuscation or delayed activation techniques.

• Compromise of Legitimate Extensions:

  • Adversaries compromise legitimate extensions by exploiting vulnerabilities in their update mechanisms, repositories, or developer accounts.

  • Once compromised, attackers inject malicious scripts or payloads into extension updates, automatically affecting installed users.

• Sideloading and Social Engineering:

  • Attackers persuade users to install malicious extensions directly from third-party websites or via social engineering campaigns.

  • Users may bypass official browser store security checks by manually installing these extensions.

• Extension Manipulation:

  • Attackers manipulate existing extensions by exploiting vulnerabilities in their scripts or APIs to execute malicious code within the browser context.

Technical mechanisms commonly seen include:

• JavaScript injection to intercept or modify web requests and responses.

• Background scripts running persistently to monitor user activities and exfiltrate data.

• Content scripts injected into web pages to manipulate user interactions or steal credentials.

• Leveraging browser permissions to access sensitive browser data such as cookies, credentials, browsing history, and bookmarks.

Real-world procedures typically include:

• Credential theft via browser session hijacking.

• Data exfiltration through covert HTTP/S requests to attacker-controlled servers.

• Browser-based cryptojacking scripts running silently in the background.

• Manipulation of web content to redirect users to malicious or phishing websites.

When this Technique is Usually Used

Attackers use browser extensions across various stages and scenarios of cyber-attacks, including:

• Initial Access and Delivery:

  • Phishing campaigns tricking users into installing malicious extensions.

  • Malvertising campaigns delivering extensions through deceptive advertisements.

• Persistence:

  • Malicious extensions automatically load and execute upon browser startup, ensuring persistent access to user data and browsing sessions.

• Credential Access and Data Collection:

  • Extensions silently collect user credentials, session tokens, browsing history, and personal information for espionage, identity theft, or financial fraud.

• Command and Control (C2):

  • Extensions communicate with attacker-controlled servers to receive commands, updates, or exfiltrate stolen data.

• Impact and Manipulation:

  • Extensions alter web page content, redirect users to malicious resources, or inject malicious advertisements and scripts.

How this Technique is Usually Detected

Detection of malicious browser extensions typically involves a combination of endpoint monitoring, network analysis, and behavioral anomaly detection:

• Endpoint Detection and Response (EDR) Tools:

  • Monitoring browser extension installation events, updates, and modification activities.

  • Analyzing browser extension files and scripts for suspicious or malicious code patterns.

• Network Traffic Analysis:

  • Identifying anomalous outbound connections from browsers to unknown or suspicious domains.

  • Detecting unusual patterns of data exfiltration or beaconing behavior indicative of command-and-control communication.

• Browser Security Policies and Controls:

  • Implementing enterprise browser management tools to audit and control allowed extensions.

  • Using browser security extensions or built-in browser security features to detect unauthorized or suspicious extensions.

• Behavioral Analysis and Anomaly Detection:

  • Monitoring browser processes for abnormal CPU, memory, or network usage indicative of cryptojacking or data exfiltration.

  • Detecting unauthorized changes to browser settings, such as homepage or search engine modifications.

• Indicators of Compromise (IoCs):

  • Presence of unknown or suspicious browser extension IDs.

  • Unusual browser behavior or frequent redirections to unknown websites.

  • Detection of suspicious JavaScript code patterns, such as obfuscated scripts, unusual API calls, or unauthorized data access attempts.

  • Unexpected network connections or DNS queries to known malicious domains or IPs.

Why it is Important to Detect This Technique

Early detection of malicious browser extensions is critical due to their potential severe impacts on systems, networks, and user privacy:

• Credential Theft and Identity Fraud:

  • Attackers can steal credentials, session cookies, and sensitive personal information, leading to identity theft, financial fraud, or unauthorized account access.

• Data Exfiltration and Espionage:

  • Malicious extensions silently exfiltrate sensitive corporate or personal data, resulting in data breaches, regulatory compliance issues, and reputational damage.

• Persistent Access and Lateral Movement:

  • Extensions provide persistent, stealthy footholds, allowing attackers prolonged access to user environments, enabling lateral movement and deeper compromise.

• Resource Hijacking and Performance Degradation:

  • Cryptojacking extensions consume system resources, degrading system performance and increasing energy consumption.

• Manipulation and Redirection:

  • Attackers redirect users to phishing sites, malicious downloads, or fraudulent advertisements, increasing exposure to further attacks and malware infections.

Given these significant risks, organizations must prioritize detecting and mitigating malicious browser extensions to protect users, sensitive data, and overall cybersecurity posture.

Examples

Real-world examples demonstrate how attackers leverage malicious browser extensions in cyber-attacks:

• Mega.nz Chrome Extension Compromise (2018):

  • Attackers compromised the legitimate Mega.nz Chrome extension by injecting malicious JavaScript code.

  • Malicious code stole login credentials and cryptocurrency wallet private keys from users.

  • Impact: Over 1.6 million users potentially affected, highlighting risks associated with compromised legitimate extensions.

• Nigelthorn Malware Campaign (2018):

  • Attackers distributed malicious Chrome extensions through Facebook messages linking to fake YouTube pages.

  • Extensions stole social media credentials, propagated malware, and performed cryptojacking operations.

  • Impact: Over 100,000 users infected, significant data theft, and unauthorized cryptocurrency mining.

• DataSpii Leak (2019):

  • Multiple browser extensions, including "Hover Zoom" and "SpeakIt!", collected and leaked sensitive browsing data.

  • Data included URLs, page titles, and personal information, sold to third parties.

  • Impact: Millions of users affected, highlighting privacy risks from seemingly benign extensions.

• Razy Malware Campaign (2019):

  • Malware installed malicious browser extensions in Chrome, Firefox, and Yandex browsers.

  • Extensions intercepted cryptocurrency wallet addresses and redirected cryptocurrency transactions to attacker-controlled wallets.

  • Impact: Financial losses for users and organizations, demonstrating direct financial theft via malicious extensions.

These examples underscore the critical importance of closely monitoring and managing browser extensions to prevent severe cybersecurity incidents and data breaches.