As organizations shift to browser-based applications and cloud-first workflows, attackers are likewise redirecting their focus from traditional malware to stealthier, more deceptive techniques. Two rising threats, malicious browser extensions and drive-by attacks, are silently compromising users without the need for downloads or triggering obvious red flags.
Let’s explore how these threats work, real-world examples, how to defend against them, and what cybersecurity professionals need to know.
Browser extensions are small software modules that customize and enhance browser functionality. However, attackers can exploit them to:
Most of the time, malicious browser extensions can gain access to compromise extensions using legitimate means, often by simply publishing an extension to the store. An attacker may publish a malicious application that masquerades as a productivity tool, security add-on, or a plugin that has entertainment value. However, once the extension is installed, it may execute malicious commands that carry out nefarious tasks such as the following:
1. Stealing data: Disguised as legitimate tools, these extensions can harvest usernames, passwords, browsing history, cached session tokens, and credit card data, then exfiltrate it to attacker-controlled servers.
2. Session hijacking: Attackers can use malicious browser extensions to intercept web sessions and even manipulate these, allowing them the ability to take over online accounts and sensitive applications.
3. Fraudulent advertising and click hijacking: Malicious extensions have many capabilities that can inject unauthorized ads and redirect searches. Malicious browser extensions can also modify affiliate links to generate fraudulent revenue or redirect revenue to attacker’s accounts.
4. Account takeover attacks: If an extension has access to authentication cookies and session tokens, attackers can impersonate users on sensitive websites or other web resources.
5. Persistence mechanisms: Attackers may try to add in built-in mechanisms to avoid detection. These may include disabling browser security settings, using encrypted command-and-control communications, or automatically reinstalling the extension if it gets uninstalled.
Security has often been described as “layers of an onion” or multi-layered approach. Organizations must adopt practices and methodologies along with the right technology tools to bolster security when it comes to browser extensions and SaaS apps. Note the following:
1. Continuous risk assessmentMonitoring all browser extensions used in the organization is a vital step to securing browser extension use. In addition to a simple inventory of extensions used in the environment, organizations must perform effective risk assessments. These risk assessments should include the permissions requested by each extension, known security vulnerabilities, and track all updates to the extension that could have malicious intent.
2. Automated extensions policies and enforcementRather than suggest that users should only install recommended extensions, companies need to introduce and enforce strict policies around which extensions users can and cannot install.
3. User education
Cybersecurity awareness training should include browser hygiene and help users identify suspicious browser extensions to avoid installing extensions from untrustworthy sites. Training should cover:
Malicious browser extensions and drive-by attacks are often overlooked due to their subtlety and dependence on user behaviour. However, their impact can be severe ranging from account compromise to full endpoint takeovers.
As browsers become the de facto operating system of the modern workforce, it’s critical for individuals and organizations to treat browser security as seriously as OS-level defenses.
Stay vigilant, review what’s running in your browser, and remember: sometimes the simplest click is all it takes.
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