Top 8 Browser Exploits and Attacks and How to Defend Your Organization

What Is a Browser Exploit?

A browser exploit is a malicious technique used by attackers to compromise web browsers. These exploits take advantage of bugs, unpatched vulnerabilities, insecure website code, or flaws in browser code to execute unauthorized actions. Attackers often deploy these exploits to infiltrate user systems, steal sensitive data, or install malware. The execution of such exploits typically happens without user consent or awareness.

Browser exploits are a significant cybersecurity threat due to the central role browsers play in modern internet usage. As they are the primary interface between users and the web, any weak link can expose private information. This threat is especially severe in enterprise environments. Therefore, securing browsers and staying informed about potential exploits is crucial for protecting both individual users and businesses.

This is part of a series of articles about browser security

In this article:

• What Can You Do Today to Prevent Browser Exploits?
• Why Do Browser Exploits Occur?
• 8 Types of Browser Exploits and Attacks
• How Modern Browsers Are Fighting Exploits

What Can You Do Today to Prevent Browser Exploits?

Web browsers are often the first line of contact with the internet, making them a frequent target for cyberattacks. There are several practical steps individuals and organizations can take today to reduce their exposure to browser exploits.

1. Ensure All Software Is Up to Date

Keep your browser, plugins, and operating system updated to the latest versions. Most exploits rely on known vulnerabilities that have already been patched by developers. Enable automatic updates wherever possible and routinely check that patches are applied. Outdated software significantly increases the likelihood of a successful exploit, especially when targeting widely known CVEs.

2. Always Use HTTPS

Ensure websites are accessed via HTTPS to protect data in transit from interception or tampering. Browsers today warn users about insecure (HTTP) connections, but users should still verify the padlock icon and domain before submitting sensitive information. Site administrators must enforce HTTPS using HTTP Strict Transport Security (HSTS) and correctly configure SSL/TLS certificates.

3. Only Use Extensions for Trusted Sources

Install browser extensions only from official web stores and well-known developers. Review permissions before installation—avoid extensions asking for more access than necessary. Regularly audit installed extensions and remove those that are no longer needed or seem suspicious. Organizations should use administrative controls to allowlist approved extensions and block others.

4. Use a Secure Browser

Use a modern browser that receives frequent updates, supports sandboxing, and enforces strong security policies like site isolation. Avoid outdated or obscure browsers that may lack adequate vulnerability management. For enterprise use, consider security-augmented browser solutions or dedicated enterprise browsers that enforce strong security configurations and organizational policies.

Why Do Browser Exploits Occur?

Vulnerabilities in Browser Software

Browser software vulnerabilities arise from coding errors, insufficient testing, or outdated architectures. These vulnerabilities often act as entry points for hackers. Browsers must handle complex tasks like rendering HTML, running scripts, and managing plugins, which increases the likelihood of security gaps. Attackers identify these loopholes to inject malicious scripts or gain access to system-level privileges, compromising the user environment.

Many vulnerabilities stem from delayed patch management. Developers may release fixes, but users sometimes fail to update their browsers promptly, providing an opportunity for exploitation. Additionally, third-party plugins and extensions that rely on old APIs can introduce risks, especially if poorly maintained or abandoned by developers.

Exploiting User Behavior

Attackers often exploit user behavior by manipulating trust and exploiting carelessness. Users are often targeted through phishing emails, misleading advertisements, or fake software updates that encourage clicking malicious links. These tactics manipulate victims into unwittingly activating browser-based exploits.

Social engineering also plays a significant role. Attackers craft scenarios where users unknowingly grant permissions or install harmful software. These behaviors lead to outcomes such as unauthorized data access or system infiltration, highlighting the importance of user awareness in preventing browser exploits.

The Role of Web Technologies

Web technologies like JavaScript, HTML5, and WebAssembly enable dynamic web experiences but come with security risks. Attackers exploit weaknesses in how browsers manage these technologies, executing malicious scripts or overloading system capabilities.

For instance, poorly sanitized inputs can lead to code injection attacks through JavaScript. In addition, modern site interactivity often involves various interconnected APIs, which attackers manipulate to bypass security restrictions. The balance between functionality and vulnerability requires careful attention from both browser developers and web application creators to minimize exploit potential.

8 Types of Browser Exploits and Attacks

Here are some of the common types of browser exploits threatening end users and organizations.

1. Cross-Site Scripting (XSS)

Cross-site scripting allows attackers to inject malicious scripts into web pages that are then executed in the browsers of unsuspecting users. These scripts typically run with the privileges of the user’s browser session, allowing attackers to steal cookies, capture keystrokes, deface websites, or redirect users to malicious domains.

XSS attacks are commonly categorized into three types: stored, reflected, and DOM-based. Stored XSS involves injecting code that is permanently stored on the server (e.g., in a comment or database), while reflected XSS is delivered via a URL or form submission. DOM-based XSS manipulates the document object model on the client side without involving the server.

How organizations can prevent it:

• Sanitize and validate all user input on both client and server sides
• Implement Content Security Policy (CSP) headers to restrict script execution
• Escape dynamic content in HTML, JavaScript, and URLs
• Use frameworks that auto-escape data (e.g., React, Angular)

2. Cross-Site Request Forgery (CSRF)

CSRF exploits the trust a website has in a user’s browser by tricking the browser into sending unauthorized commands to a web application. If a user is logged into a site like an email or banking service, an attacker can use social engineering to lure them into visiting a malicious site. That site sends requests that appear legitimate, such as transferring money or changing an email address, using the victim’s authenticated session.

How organizations can prevent it:

• Use anti-CSRF tokens for all state-changing requests
• Require re-authentication or confirmation for critical actions
• Implement SameSite cookie attributes to limit cross-origin requests
• Monitor and log unusual POST request behavior

3. Drive-By Downloads

Drive-by downloads occur when a browser or plugin is silently exploited to install malware without the user’s knowledge or explicit consent. These attacks typically use malicious scripts embedded in compromised websites or hidden within iframes and ad networks.

In drive-by attacks, the malware might exploit unpatched vulnerabilities in Java, Flash, PDF readers, or the browser itself to execute code on the system. The downloaded payload could be anything from spyware and ransomware to remote access trojans.

How organizations can prevent it:

• Regularly update browsers, plugins, and OS components
• Use browser-based sandboxing and script-blocking tools
• Disable or remove unused plugins like Flash and Java
• Scan and monitor web traffic for malicious code with endpoint protection tools

4. Browser Hijacking and Redirects

Browser hijacking modifies browser behavior without user approval, often by altering settings such as the default search engine, homepage, or new tab page. In many cases, users are redirected to phishing sites or pages loaded with intrusive ads that generate revenue for the attacker.

Hijacking can be initiated through malicious scripts, bundled software installations, or rogue browser extensions. Once hijacked, it may be difficult for users to revert settings, especially if registry values or system policies are changed.

How organizations can prevent it:

• Educate users to avoid installing software from unverified sources
• Use endpoint protection that flags unauthorized browser modifications
• Employ browser policies to restrict changes to default configurations
• Regularly audit browser settings via group policies or MDM tools

5. Clickjacking and UI Redressing

Clickjacking deceives users into clicking hidden or disguised elements on a webpage, often using transparent layers or misleading visual cues. For example, a malicious page might load an embedded frame containing a “Confirm” or “Purchase” button underneath a fake UI, so when the user thinks they’re clicking a harmless element, they’re actually performing a sensitive action. UI redressing extends this idea by manipulating the layout and styles to further obscure the true intent of on-screen elements.

How organizations can prevent it:

• Use X-Frame-Options or CSP frame-ancestors headers to prevent framing
• Implement visual verification for sensitive actions (e.g., CAPTCHA or 2FA)
• Design UI elements that are not easily obscured or mimicked
• Educate users on the risks of clicking unexpected popups or overlays

6. Zero-Day Browser Exploits

Zero-day exploits are attacks that target previously unknown vulnerabilities in browser code, often discovered and weaponized before developers have a chance to issue patches. Because they are unknown to security vendors and software providers, traditional defenses like antivirus tools and firewalls may not detect or block them. Zero-day attacks are typically used in highly targeted campaigns, such as surveillance or corporate espionage.

How organizations can prevent it:

• Employ behavior-based security solutions that detect anomalies
• Use browser isolation to contain untrusted content
• Monitor threat intelligence feeds to react quickly to new CVEs
• Enforce least privilege access and application whitelisting policies

7. Exploiting Localhost APIs

Browsers sometimes communicate with local services through localhost interfaces for integrations with desktop applications like password managers or development tools. If these services do not verify request origins or authenticate users properly, a malicious webpage can send crafted HTTP requests to the local server.

Localhost API exploits can result in executing commands, accessing files, or injecting configuration changes. For instance, some attacks target developer tools like Elasticsearch or Docker APIs, assuming they are exposed without proper access control.

How organizations can prevent it:

• Enforce authentication and origin checks on all local services
• Use network segmentation to isolate browser and local service communications
• Restrict public exposure of developer and admin tools
• Log and alert on unusual localhost access patterns

8. Malicious Browser Extensions

Browser extensions can operate with wide-ranging access, often including permissions to read and modify content on all visited websites. Malicious extensions may be disguised as legitimate utilities (e.g., ad blockers, coupon finders), but once installed, they can inject scripts, track user activity, exfiltrate credentials, or display deceptive content.

Even well-intentioned extensions can become malicious if the developer account is compromised or the extension is sold to a third party with hidden motives.

How organizations can prevent it:

• Vet all extensions before allowing installation on enterprise devices
• Use browser group policies to enforce extension allowlists
• Regularly review extension activity for signs of abuse
• Educate users about the risks of installing unverified add-ons

Related content: Read our guide to secure browser extension (coming soon)

How Modern Browsers Are Fighting Exploits

Here are a few ways modern browser technology helps prevent exploits like the ones above. However, while browsers are more secure than they have been, they are still vulnerable to many types of attacks.

Built-In Browser Security Features

Modern browsers come with a range of built-in features to mitigate common security threats. These include mechanisms like Safe Browsing (used in Chrome and Firefox), which warns users about potentially malicious websites or downloads. Browsers also automatically block mixed content (HTTPS pages loading HTTP resources), reducing the risk of man-in-the-middle attacks.

Modern browsers isolate risky operations and implement permission prompts for access to the camera, microphone, location, and notifications. By default, they limit pop-ups, auto-downloads, and plugin execution.

Why users are still vulnerable:

• Despite built-in protections, users can override browser warnings or unintentionally approve risky permissions.
• Attackers often use social engineering to trick users into disabling safeguards or clicking through alerts.
• Browser features may not cover all threat vectors, especially those arising from third-party extensions or misconfigured websites.

HTTPS Enforcement and HSTS

Browsers increasingly enforce the use of HTTPS to secure the communication between the user and web servers. HTTPS prevents eavesdropping and tampering by encrypting data in transit. Many browsers now show warnings for HTTP pages, particularly when sensitive inputs like passwords are involved.

HTTP Strict Transport Security (HSTS) complements HTTPS by ensuring that once a site is known to support HTTPS, the browser refuses to connect via HTTP in future sessions. HSTS also blocks downgrade attacks where an attacker tries to redirect a user from HTTPS to HTTP to intercept traffic.

Why users are still vulnerable:

• Users can still encounter unencrypted HTTP sites, especially on less-trafficked or outdated domains.
• Not all websites implement HSTS, and many rely on third-party resources that may not be HTTPS-compliant.
• Advanced attackers may use DNS spoofing or SSL stripping techniques in unsecured networks to bypass HTTPS protections.

Content Security Policy (CSP)

Content security policy (CSP) is a browser feature that allows website owners to define rules for what resources (scripts, styles, images) can be loaded and executed on a page. CSP helps prevent cross-site scripting (XSS) and data injection attacks by blocking untrusted or inline scripts.

For example, a site can use CSP to allow scripts only from its own domain and known CDNs, while disallowing inline JavaScript and eval(). Browsers enforce these policies at runtime, preventing unauthorized code execution even if malicious input is injected into the page.

Why users are still vulnerable:

• CSP must be correctly implemented by the website developer, and misconfigurations are common.
• Many sites allow unsafe directives like unsafe-inline or overly broad source lists, weakening policy effectiveness.
• Attackers can also exploit CSP bypass techniques or target areas of the site not covered by the policy.

Browser Sandbox and Isolation Technologies

To limit the impact of exploits, modern browsers employ sandboxing and process isolation. Each tab, extension, or rendering task runs in a separate, restricted environment, isolated from the rest of the system. This prevents a compromised process from affecting other browser components or accessing critical system resources.

For instance, Chromium-based browsers use site isolation to separate different origins into different processes. This architecture mitigates attacks like Spectre and limits the spread of malicious activity within the browser.

Why users are still vulnerable:

• Sophisticated exploits, especially zero-days, can escape sandboxes or exploit inter-process communication flaws.
• While isolation limits damage, it doesn’t prevent initial exploitation or data theft from within a compromised process.
• Users running outdated browsers or using non-isolated extensions are particularly at risk.

Private Network Access (PNA) Protections

Private network access (PNA) is a security feature that prevents public websites from making requests to local or private IP addresses (like 127.0.0.1 or 192.168.x.x) unless explicitly allowed. This blocks common exploits that attempt to reach internal systems via browser requests.

Browsers implementing PNA require CORS headers and preflight requests for such access, protecting internal APIs or services (e.g., routers, local dashboards) from being targeted by scripts on malicious websites. This reduces the attack surface for exploits targeting localhost or internal-only services.

Why users are still vulnerable:

• Many local services lack proper CORS headers or token-based access control, leaving them open to exploitation if PNA policies are not fully enforced.
• Older browsers may not support PNA at all, and some enterprise applications intentionally weaken PNA for compatibility.
• Attackers can also exploit timing gaps during initial browser requests.

Extension and Plugin Security

Browsers have tightened controls around extensions and deprecated legacy plugins. Modern extension architectures (e.g., Manifest V3 in Chrome) limit background script access and enforce permissions transparency. Users must explicitly approve requested permissions, and browsers notify them when extensions attempt sensitive actions.

Additionally, browser stores review extensions for malicious behavior, and automated tools scan for suspicious patterns. Legacy plugins like Flash and Java applets are now disabled by default or removed entirely, closing off entire categories of high-risk exploits.

Why users are still vulnerable:

• Malicious extensions can still slip past browser store reviews or become compromised after installation through updates.
• Users often grant overly broad permissions without scrutiny.
• Attackers may exploit legitimate extensions through vulnerabilities or by purchasing and weaponizing abandoned projects.

Eliminating Browser Exploits with Seraphic Enterprise Browser Security

Seraphic’s enterprise browser security platform takes a fundamentally different approach to protecting against browser exploits by creating an isolated, secure browsing environment that prevents malicious code from ever reaching the endpoint. Rather than relying on signature-based detection that can miss zero-day exploits, Seraphic’s solution operates on the principle of isolation and containment. When users access web content, all potentially dangerous elements are processed in a secure, remote environment, with only safe, rendered pixels delivered to the user’s device. This architecture ensures that even the most sophisticated browser exploits cannot execute on corporate endpoints or access sensitive enterprise resources.

The platform’s advanced threat detection capabilities continuously analyze web content for malicious patterns, suspicious JavaScript behaviors, and exploit techniques in real-time. Unlike traditional security solutions that may allow initial compromise before detection, Seraphic’s proactive approach prevents exploitation attempts from succeeding in the first place. The system maintains complete visibility into all web-based activities while providing detailed analytics and reporting that help security teams understand their threat landscape and adjust policies accordingly.

Seraphic’s solution seamlessly integrates into existing enterprise security stacks without requiring changes to user workflows or browser configurations. Employees can continue using their preferred browsers and web applications while remaining protected from drive-by downloads, malicious advertisements, weaponized documents, and other browser-based attack vectors. The platform scales to support organizations of any size, providing consistent protection across distributed workforces, remote employees, and bring-your-own-device (BYOD) environments where traditional endpoint security may be limited or unavailable.

Learn more about Seraphic Security’s award-winning solutions here.