Protecting Against Brand Impersonation Attacks with Browser Detection and Response

By Tejeswara S Reddy, Security Researcher, SquareX

Brand impersonation attacks occur when threat actors create convincing replicas of legitimate websites, communications, or digital assets to deceive users into believing they are interacting with a trusted entity. As traditional security measures struggle to keep pace, browser detection and response (BDR) capabilities are emerging as a critical component in the fight against these tactics.

Early phishing attempts were relatively easy to identify through obvious red flags: poor grammar, suspicious URLs, or unprofessional design elements. Today’s brand impersonation attacks, however, have evolved dramatically:

• Pixel-perfect visual replication: Attackers now create exact visual duplicates of legitimate websites, down to the logos, color schemes, and layouts.
• Look-alike domains: Attackers register domains that appear nearly identical to legitimate ones, using homoglyphs (similar-looking characters), typosquatting, or adding terms like “secure” or “login” to domain names.

The browser is a complex application, akin to an operating system on its own. Attackers are exploiting various aspects of the browser and orchestrating attacks that render entirely on the client side. Existing security solutions like Secure Web Gateways as part of SASE/SSE solutions are unable to protect users against modern web threats that happen on the client side, and endpoint security solutions have no visibility into what happens in the browser during an attack.

Traditional security approaches face significant limitations when confronting modern brand impersonation attacks:

• Email security controls: Many attacks now bypass email entirely by leveraging social media, messaging platforms, or legitimate but compromised websites.
• URL Filtering and Blacklists: Reactive approaches like URL blacklists simply cannot keep pace with the rapid deployment and short lifespan of modern phishing sites. Research shows that the average phishing site exists for less than 24 hours before being taken down or moved to a new domain, making blacklist-based protection insufficient.
• Static Analysis: Static analysis of websites based on known signatures cannot effectively identify new or modified impersonation sites — there are far too many components that make up a web page now that don’t get picked up by static analysis.

The Browser-Based Detection Advantage

Browser detection and response solutions offer several critical advantages in addressing the brand impersonation challenge:

Real-Time Visual Analysis

Browser-based security solutions can analyze the visual elements of web pages in real-time, identifying unauthorized use of logos, brand assets, and design elements even when the underlying code has been modified to evade traditional detection methods.

DOM Analysis and Behavioral Monitoring

Browser extensions and security tools can monitor Document Object Model (DOM) manipulations and user interactions in real-time, identifying suspicious behaviors such as:

• Hidden form fields capturing additional data
• Keystroke logging through JavaScript
• Attempts to capture autocomplete data
• Form submission to unexpected domains

In-Context Detection

Unlike network-level solutions, browser-based detection occurs within the actual user experience context, allowing for more nuanced analysis of:

• The logical flow of user navigation
• Inconsistencies between visual elements and underlying code
• Behavioral patterns indicating deception
• Context-specific risk factors (e.g., financial transactions)

Real-World Case Studies

Case Study 1: The X Account Hijacking Campaign

In early 2025, a sophisticated phishing campaign targeted high-profile accounts on X (formerly Twitter). The attack was notable for several reasons:

1. Deceptive Communications: Users received emails impersonating official X notifications, such as security alerts or copyright violation warnings. These emails contained links leading to fake login pages designed to steal credentials.

2. Bypassing Security Filters: Attackers used Google’s AMP Cache (cdn.ampproject[.]org) to make malicious links appear legitimate, enabling them to bypass email security measures.

3. Session Hijacking: Using advanced techniques like Man-in-the-Middle (MitM) attacks with Evilginx, attackers intercepted authentication tokens during login, allowing them to bypass multi-factor authentication (MFA).

Traditional security measures failed to detect this campaign because the phishing emails appeared to be legitimate X notifications, and the use of AMP links helped evade filtering.

Browser security extensions like SquareX provided an extra layer of protection. SquareX’s brand impersonation policy automatically blocks access to fake websites that attempt to mimic trusted brands, preventing users from interacting with phishing pages. This proactive defense mechanism significantly reduced the risk of credential theft by stopping users from unknowingly entering their information on fraudulent sites.

Demonstration: SquareX Prevents the X Account Hijacking Attack

Case Study 2: The Insidious Phishing Technique

In 2025, attackers devised a stealthy phishing technique that exploited how users quickly scan URLs. The attack was notable for several reasons:

• Deceptive URL Structuring: Phishing links were crafted to look like legitimate domains by embedding trusted brand names within subdomains. For example, a fraudulent URL like microsoft.com.en.us.microsoft-365.linkanaccount.com/login could mislead users into thinking they were on an official Microsoft page, while the real domain (linkanaccount.com) controlled the site.

• Brand Impersonation: Attackers used misleading subdomains to mimic trusted language codes and structure URLs in a way that made them appear legitimate at first glance.
• Advanced Evasion Techniques: Traditional security measures struggled to detect these phishing attempts because they did not involve obvious domain spoofing but rather subtle URL manipulation.

Standard security tools often failed to prevent these attacks since users were tricked into clicking on what appeared to be trusted links. However, SquareX’s BDR solution effectively mitigated the threat:

• Immediate Phishing Site Detection: As soon as a user attempted to access a phishing page, SquareX identified the brand impersonation attempt and blocked access before credentials could be entered.
• Enhanced Security Team Visibility: SquareX provided full tracking of phishing attempts, allowing security teams to analyze how users landed on scam sites.
• Detailed Attack Graphs & Reports: Security admins could review in-depth visualizations of attack paths and identify high-risk behaviors.
• Attack Vision Playback: SquareX’s Attack Vision feature enabled a full playback of the phishing attempt, helping teams understand the tactics used and further strengthen security operations.

By proactively detecting and blocking these deceptive phishing URLs, SquareX significantly reduced the risk of credential theft and improved overall cybersecurity resilience.

Demonstration: How SquareX Prevented this impersonating subdomain trick

Implementing Effective Browser-Based Protection

Organizations looking to enhance their defense against brand impersonation should consider a multi-layered approach:

1. Deploy Browser-Based Security Extensions

Enterprise-grade browser extensions can provide real-time protection by:

• Analyzing page content for unauthorized brand usage
• Monitoring form submissions and credentials entered on suspicious sites
• Alerting users to potential brand impersonation attempts

2. Behavioral Analysis and Machine Learning

Modern solutions leverage machine learning to improve detection accuracy by:

• Establishing baselines of normal user behavior
• Identifying anomalies in website structure and behavior
• Learning from previous attack patterns
• Adapting to new threat vectors as they emerge

The Future of Brand Impersonation Protection

As we look ahead, several trends will shape the evolution of browser-based brand impersonation protection:

Browser-based detection will increasingly become a key signal in zero trust authentication decisions, with suspicious visual or behavioral patterns triggering additional verification steps before allowing access to sensitive resources.

Organizations must adopt a multi-layered approach that combines traditional security controls with browser-based detection, continuous monitoring to effectively combat the growing threat of brand impersonation. By moving security closer to the user experience, we can build more resilient defenses against even the most convincing impersonation attempts.

Learn More

SquareX is the industry’s first Browser Detection and Response (BDR) solution that helps organizations detect, mitigate and threat-hunt client-side web attacks targeting employees happening against their users in real time. See more in our brand impersonation video below:

Protecting Against Brand Impersonation Attacks with Browser Detection and Response was originally published in SquareX Labs on Medium, where people are continuing the conversation by highlighting and responding to this story.

*** This is a Security Bloggers Network syndicated blog from SquareX Labs - Medium authored by Engineering @ SquareX. Read the original post at: https://labs.sqrx.com/protecting-against-brand-impersonation-attacks-with-browser-detection-and-response-ba65ab8661a3?source=rss----f5a55541436d---4