What is Browser Hijacking?
Browser hijacking is a type of cyberattack where malicious software modifies your web browser's settings without your permission. Attackers typically do this to generate advertising revenue by forcing your browser to visit specific websites, often malicious ones, or to steal sensitive personal information like passwords and banking details.
Warning signs of hijacking:
If a browser has been hijacked, users may notice the following:
- Changed settings: Homepage, default search engine, or new tab page has been replaced with something unfamiliar.
- Unwanted redirects: When a user tries to visit a website or perform a search, they are automatically sent to a completely different, often ad-heavy or suspicious site.
- Performance issues: Web pages load much slower than usual, or the browser crashes frequently.
- Excessive pop-ups: Users are bombarded with an unusual number of pop-up ads, sometimes even when not actively browsing.
- New toolbars/extensions: Unfamiliar buttons, toolbars, or extensions appear in the browser that the user did not install.
How hijackers infect a device:
Most hijackers aren't "hacked" in the traditional sense; they are usually installed through user actions:
- Bundled software: They are often packaged as "optional offers" inside the installers of free software (freeware) or shareware.
- Malicious extensions: Seemingly helpful browser extensions (like file converters or coupon finders) may contain hidden hijacking code.
- Deceptive links: Clicking on links in phishing emails, social media posts, or pop-up "update" alerts can trigger silent downloads.
- Compromised websites: Simply visiting a malicious site can sometimes initiate a "drive-by download" containing a hijacker.
This is part of a series of articles about malware attack
In this article:
- How Browser Hijacking Works
- Browser Hijacking Warning Signs
- How Do Hijackers Infect Devices?
- How to Remove Browser Hijacking from a Browser: Step by Step
- 6 Ways to Prevent Browser Hijacking
How Browser Hijacking Works
Browser hijacking works by modifying browser settings, configuration files, shortcuts, extensions, registry entries, or policies that control browser behavior. Once installed, the hijacker establishes persistence so its changes remain active even after the user attempts to restore settings. Some variants continuously monitor browser configurations and automatically reapply malicious settings whenever they are changed.
More advanced hijackers inject scripts into webpages, intercept search queries, alter DNS or proxy settings, and redirect web traffic through attacker-controlled infrastructure. This allows attackers to display advertisements, collect browsing data, manipulate search results, or direct users to phishing pages and malware distribution sites.
Typical attack process:
- Initial delivery: The user installs bundled software, clicks a deceptive link, installs a malicious extension, or visits a compromised website.
- Execution: The hijacker is installed on the device and gains access to the browser environment.
- Configuration changes: Browser settings such as the homepage, search engine, new tab page, shortcuts, DNS settings, or proxy settings are modified.
- Persistence setup: The hijacker creates registry entries, scheduled tasks, startup items, browser policies, or helper programs that allow it to survive reboots and browser restarts.
- Traffic manipulation: Search queries and website requests are redirected through attacker-controlled services or advertising networks.
- Data collection: Browsing activity, search history, IP addresses, and other user information may be gathered for profiling or monetization.
- Monetization or exploitation: The attacker generates revenue through advertisements, affiliate fraud, forced traffic, data collection, phishing campaigns, or delivery of additional malware.
- Reinforcement: If the user attempts to restore settings, the persistence mechanisms reapply the malicious configuration and maintain control of the browser.
Browser Hijacking Warning Signs
1. Changed Settings
One of the most common signs of browser hijacking is unexpected changes to browser settings. You might notice your default search engine, homepage, or new tab page has changed to an unfamiliar site. These changes often occur without your approval, and attempts to restore your preferred settings may be undone after a restart or when the browser is relaunched.
Hijackers may also alter security or privacy configurations, lowering your browser’s defenses against further attacks. This can expose you to additional threats or unwanted tracking. If your settings revert despite attempts to fix them, it is a strong indicator that a hijacker is controlling your browser environment.
2. Unwanted Redirects
Another indicator of browser hijacking is being redirected to unfamiliar or suspicious websites, especially when trying to visit well-known pages. Instead of reaching your intended destination, you may be taken to search engines you have not chosen, ad-heavy landing pages, or phishing sites designed to steal your information.
These redirects generate ad revenue, collect data, or expose you to more malware. Frequent or persistent redirects should not be ignored, as they can indicate the presence of a hijacker interfering with your browsing activity.
3. Performance Issues
Browser hijackers often cause slowdowns in browser performance. Pages may take longer to load, tabs might become unresponsive, or the browser may freeze or crash more frequently than usual. These issues often result from injected scripts, excessive ads, or background processes running without your knowledge.
Over time, the impact on system resources can extend beyond the browser, causing general slowness across your device. If you observe a decline in both browser and system performance after noticing other hijacking symptoms, malicious software may be consuming resources.
4. Excessive Pop-Ups
An increase in intrusive pop-up ads is a common sign of browser hijacking. These pop-ups can appear even when you are not visiting ad-heavy sites and may display misleading warnings, fake prize notifications, or prompts to install additional software. Their goal is to generate revenue or trick users into further compromising their systems.
Pop-ups from a hijacked browser can also lead to more serious threats if clicked. Many contain malicious links or initiate downloads that deepen the infection. Persistent pop-up activity indicates that your browser may be compromised.
5. New Toolbars/Extensions
Finding new toolbars or extensions that you do not remember installing is another signal of hijacking. These add-ons often appear alongside other symptoms and are intended to collect data, inject ads, or provide attackers with control over your browsing session. They typically have generic or misleading names.
These unwanted extensions may resist removal or reinstall themselves after deletion, indicating a deeper infection. If your browser interface suddenly includes unfamiliar icons, menus, or toolbars, investigate their source and consider the possibility of a hijacker.
How Do Hijackers Infect Devices?
Bundled Software
Software bundling is one of the most common ways browser hijackers reach devices. Developers or distributors package unwanted programs together with legitimate applications, allowing multiple programs to install through a single setup process.
Users often accept the bundled software unintentionally because installation screens are skipped quickly or default settings automatically approve additional offers. In some cases, installers make these offers difficult to identify or decline, increasing the likelihood that a browser hijacker is installed alongside the intended application.
How to prevent:
- Download software only from official vendor websites and trusted app stores.
- Choose custom or advanced installation options instead of express settings.
- Review each installation screen carefully before proceeding.
- Decline optional software, toolbars, and browser extensions you do not need.
- Avoid software from third-party download portals that commonly bundle additional programs.
Malicious Extensions
Browser hijackers are frequently distributed through malicious browser extensions disguised as useful tools. These extensions may claim to provide features such as coupon finding, ad blocking, productivity enhancements, or search assistance while secretly modifying browser settings and monitoring user activity.
Once installed, they can change homepages, redirect searches, inject advertisements, and collect browsing data. Because extensions often request broad permissions, users may unknowingly grant access that allows the hijacker to control browser behavior.
How to prevent:
- Install extensions only from trusted developers and reputable sources.
- Review requested permissions before installation.
- Read user reviews and check the extension’s reputation.
- Remove extensions that are no longer needed.
- Periodically audit installed browser extensions for suspicious activity.
Deceptive Links
Deceptive links are commonly used to deliver browser hijackers through phishing emails, social media messages, online advertisements, and compromised websites. These links are designed to appear legitimate while directing users to malicious downloads or webpages that execute harmful scripts.
Some attacks rely on drive-by downloads that begin automatically when a user visits a page. Others exploit unpatched browser vulnerabilities to install unwanted software without requiring a direct download.
How to prevent:
- Avoid clicking links from unexpected emails or messages.
- Verify the sender before opening attachments or following links.
- Hover over links to inspect their destination before clicking.
- Ignore pop-ups that urge immediate downloads or software updates.
- Keep browsers and operating systems updated to reduce vulnerability exploitation.
Compromised Websites
Compromised websites can infect visitors with browser hijackers by hosting malicious code that exploits weaknesses in browsers, plugins, or operating systems. Attackers sometimes compromise legitimate websites and inject malicious scripts, making it difficult for users to recognize the danger.
When a vulnerable device visits the site, the malicious code may trigger downloads, redirect traffic, or install software without the user’s knowledge. Outdated browsers and unsupported plugins significantly increase the risk of these attacks succeeding.
How to prevent:
- Keep browsers, plugins, and operating systems fully updated.
- Use security tools that block known malicious websites.
- Avoid visiting suspicious or unfamiliar websites.
- Disable or remove unnecessary browser plugins.
- Enable safe browsing features provided by modern browsers.
How to Remove Browser Hijacking from a Browser: Step by Step
Removing browser hijacking in a business environment should be handled as an endpoint remediation task, not only as a browser reset. Admins should identify the source of the configuration change, remove persistence mechanisms, restore browser policies, and confirm that the hijacker cannot reapply itself after reboot or user sign-in.
1. Isolate the Affected Device
Start by isolating the affected endpoint from the corporate network if there are signs of active compromise, credential theft, malware delivery, or suspicious outbound traffic. If full isolation is not immediately possible, restrict the device’s network access while maintaining administrative control through approved security tools.
Before making changes, collect basic evidence for investigation. Record the affected user, hostname, browser versions, installed extensions, suspicious URLs, redirect destinations, recently installed applications, proxy settings, DNS settings, and any security alerts related to the device.
2. Identify the Scope of the Hijacking
Determine whether the issue affects one browser, multiple browsers, or the entire operating system. If only one browser is affected, the cause may be a malicious extension, altered profile, or browser-specific policy. If all browsers are affected, check for system-level changes such as proxy modification, DNS tampering, malicious startup entries, or installed unwanted software.
Admins should also confirm whether the browser is legitimately managed by the organization. A “managed by your organization” message is normal on corporate devices, but it becomes suspicious if unauthorized policies appear, settings cannot be changed, or unfamiliar extensions are force-installed.
3. Review Browser Policies
Check the active browser policies applied to Chrome, Edge, Firefox, or any other supported enterprise browser. Look for unauthorized policies that control the homepage, startup pages, default search provider, extension installation, proxy settings, DNS behavior, or update controls.
Remove only policies that are not part of the organization’s approved configuration baseline. In managed environments, this should be done through the correct management channel, such as Group Policy, MDM, Intune, configuration profiles, or browser cloud management. Avoid manual deletion unless the device is unmanaged or the policy source is clearly malicious.
4. Remove Suspicious Extensions
Review all installed extensions and compare them against the organization’s approved extension list. Remove extensions with unknown publishers, excessive permissions, vague descriptions, poor reputation, or behavior linked to redirects, injected ads, search manipulation, or data collection.
For extensions installed by policy, remove the policy that force-installs them before attempting browser-level removal. If the extension returns after deletion, investigate the policy source, endpoint management profile, registry entry, configuration file, or local persistence mechanism responsible for reinstalling it.
5. Remove Unwanted Applications
Inspect recently installed applications, browser helper objects, search tools, coupon tools, download managers, PDF converters, “safe search” utilities, and other potentially unwanted programs. Browser hijackers are often installed as part of bundled software and may not appear as obvious malware.
Uninstall suspicious applications using approved endpoint management tools or the operating system’s software removal interface. After removal, check whether related services, drivers, folders, scheduled tasks, or startup entries remain on the endpoint.
6. Check Startup and Persistence Locations
Review common persistence locations that may be used to reapply browser changes after reboot. These include startup folders, login items, launch agents, scheduled tasks, services, registry run keys, browser policy paths, shell extensions, and endpoint scripts.
Remove unauthorized entries that launch unknown executables, scripts, browser processes with unusual parameters, or helper programs from temporary directories, user profile folders, or untrusted locations. When possible, preserve suspicious artifacts for analysis before deletion.
7. Inspect Proxy, DNS, and Network Settings
Check whether the hijacker modified system proxy settings, browser proxy settings, DNS servers, DNS-over-HTTPS settings, hosts files, VPN profiles, or network adapters. Unauthorized changes can redirect traffic even after browser settings are restored.
Reset proxy and DNS settings to the organization’s approved baseline. Confirm that endpoints are using trusted DNS resolvers, approved secure DNS configuration, and sanctioned VPN or web filtering services. Review firewall and EDR logs for connections to suspicious redirect domains or advertising networks.
8. Reset Browser Settings
After removing the source of persistence, reset the affected browser settings. Restore the approved homepage, startup page, new tab behavior, search engine, content settings, notification permissions, and privacy settings. Remove unknown site permissions, especially permissions for notifications, pop-ups, redirects, downloads, and background sync.
If the profile appears heavily modified, create a new browser profile or delete the compromised profile after backing up approved business data such as bookmarks. Avoid restoring full browser sync data until malicious extensions and settings have been removed from the user’s synced account.
9. Clear Cache, Cookies, and Site Data
Clear cached files, cookies, local storage, and site data related to suspicious domains. This helps remove tracking artifacts, redirect scripts, and stored permissions that may continue affecting the browsing session.
In enterprise environments, admins can perform this through browser management tools, endpoint scripts, or user-profile remediation workflows. Make sure business-critical session data is considered before clearing all browser data.
10. Run Endpoint Security Scans
Run a full scan with the organization’s approved EDR, antivirus, or anti-malware platform. Include potentially unwanted application detection if that option is available. Review detections for adware, suspicious scripts, unauthorized browser extensions, credential stealers, and persistence tools.
If the scan detects malware beyond a simple browser hijacker, escalate the incident according to the organization’s incident response process. Consider credential resets, lateral movement checks, and additional forensic review if there are signs of data theft or broader compromise.
11. Reboot and Validate Remediation
Restart the endpoint and reopen the affected browser. Confirm that the homepage, search engine, new tab page, extensions, proxy settings, DNS settings, and policies remain clean after reboot. Perform test searches and visit common websites to confirm that redirects no longer occur.
If the hijacking returns, persistence is still present. Recheck policy sources, scheduled tasks, startup entries, installed applications, browser sync, and endpoint management profiles until the reapplying mechanism is identified and removed.
6 Ways to Prevent Browser Hijacking
1. Download Software Only From Trusted Sources
Prevent browser hijacking by downloading software only from official vendor websites or reputable app stores. Third-party download portals often bundle applications with adware, extensions, or hijackers that install during setup.
Verify the publisher and review installation prompts carefully. Avoid cracked software, unofficial installers, and pirated applications. Choose custom or advanced installation options to identify and decline bundled software.
Verify digital signatures and checksums when downloading security-sensitive tools or enterprise software. Review URLs carefully and avoid links from pop-ups or unsolicited emails.
2. Control Which Browser Extensions Can Be Installed
Install browser extensions only when necessary and from trusted developers. Many hijacking incidents begin with malicious or poorly reviewed extensions that request excessive permissions.
Organizations can use browser management policies to limit approved extensions. Individual users should regularly review installed add-ons and remove unfamiliar ones. Pay attention to permissions that allow reading browsing activity, modifying webpages, or changing search settings. Monitor extensions for unusual behavior after installation. Remove extensions that are no longer needed.
3. Use Application Control and Allowlisting to Block Unauthorized Code
Use application control and allowlisting to prevent unauthorized software, scripts, and browser components from executing. Browser hijackers often rely on users running unapproved installers, malicious scripts, or bundled applications that bypass basic security controls.
Allowlisting technologies such as Microsoft AppLocker, Windows Defender Application Control (WDAC), or third-party endpoint protection tools can restrict execution to approved applications only. This reduces the risk of malicious browser extensions, helper objects, startup programs, and installers running on endpoints.
Block unsigned executables, unauthorized PowerShell scripts, and software launched from temporary or download directories. Restrict scripting engines and command-line tools that attackers commonly abuse to modify browser settings or establish persistence.
4. Keep Browsers, Operating Systems, and Security Tools Updated
Keep browsers, operating systems, and security software updated to prevent browser hijacking. Updates include patches for vulnerabilities that attackers exploit to install malware or execute malicious scripts through compromised websites and deceptive advertisements.
Outdated software increases exposure to drive-by downloads and exploit kits that target known weaknesses. Enable automatic updates to apply patches quickly. Regular updates also improve antivirus and anti-malware detection.
Keep browser plugins and supporting software current, or remove them if no longer needed. Outdated PDF readers, media components, or browser helper objects can introduce vulnerabilities.
5. Use Managed Browser Policies
Managed browser policies allow administrators to control browser behavior and enforce security settings across devices. These policies can prevent unauthorized changes to search engines, homepages, extensions, and other configurations targeted by hijackers.
Organizations can use browser management tools from vendors such as Google Chrome or Microsoft Edge to enforce approved settings and disable risky features. Centralized control reduces the likelihood of users installing malicious extensions or altering protections. Managed policies can enforce safe browsing features, restrict access to dangerous websites, and apply security updates.
6. Apply Least Privilege Access and Deny by Default
Apply least privilege access by giving users only the permissions required for their tasks. Browser hijackers often rely on elevated privileges to install software, modify registry settings, change browser configurations, or establish persistence mechanisms.
Restrict local administrator access on workstations and servers. Standard user accounts reduce the ability of malicious installers, scripts, or extensions to make system-level changes. Administrative privileges should be granted only when necessary and monitored closely.
Use Deny-by-Default security controls to block unapproved applications, scripts, and browser modifications unless explicitly allowed. This approach reduces the attack surface and limits opportunities for hijackers to execute unauthorized code.
How Airlock Digital Browser Extension Control Helps Prevent Browser Hijacking
Because malicious browser extensions are one of the most common ways attackers seize control of a browser, controlling which extensions are allowed to run shuts down this attack path directly. Airlock Digital extends application control to the browser layer with Browser Extension Control, securing browsing environments across Chrome, Edge, and Firefox by allowing only trusted extensions to run. This reduces the risk of malicious add-ons compromising sensitive data or introducing vulnerabilities such as ransomware or malware, and supports a Zero Trust approach in which unapproved or modified extensions are blocked before they can alter settings, redirect traffic, or harvest data.
Key capabilities of Airlock Digital Browser Extension Control:
- Trusted extension allowlisting: Define and enforce which browser extensions are approved based on specific properties, including Extension ID, so only vetted add-ons can run.
- Untrusted extension blocking: Automatically prevent unapproved or modified extensions from executing, closing off the malicious extensions that hijackers rely on.
- Phishing and credential-theft mitigation: Block extensions designed to steal credentials or sensitive data, reducing exposure to data theft.
- Typo-squatting prevention: Restrict users from accidentally installing unapproved extensions that imitate legitimate ones.
- Centralized management: Monitor and control browser extensions across all endpoints from a single, unified console.
- Comprehensive reporting: Gain visibility into extension usage and ensure compliance with organizational policies.
To see how your organization can proactively shut down browser-based threats, learn more about Airlock Digital Browser Extension Control.