Modern Browser Attacks: Why Perimeter Tools Are No Longer Enough

The browser has quietly become the most critical application in the enterprise — and the most targeted. With SaaS, cloud, and hybrid work redefining IT boundaries, browsers now handle proprietary data, credentials, and business workflows. Yet legacy security tools like firewalls, antivirus, and EDR were never designed to defend this new digital front line.

The shift from being an ancillary tool to becoming the main location of work means legacy security solutions, such as firewalls, antivirus, VDI, etc., are not equipped to provide the necessary level of protection needed to secure today's organizations. The browser, once an afterthought, is now the weak link that legacy defenses simply can't secure.

This article examines the modern browser exploitation playbook and details why legacy tools alone are no match for today's cybercriminals. By adopting a Secure Enterprise Browser (SEB), enterprises can complement their existing security tools, shore up their weak link, and future-proof themselves against AI-born attacks.

The Modern Attacker's Playbook

Adversaries evolve their tactics continuously, leveraging the latest technologies in AI, social trends, and cloud environments. This playbook details the most pressing attack strategies observed in today's ever-changing threat landscape.

Rapid, Chained Zero-Days

Browser producers like Google, Microsoft, and Apple are patching at record pace, but attackers continue to one up them by chaining exploits. Recent vulnerabilities such as CVE-2025-6554 and CVE-2025-10585 were exploited in the wild just days after being disclosed. These multi-stage attacks use drive-by downloads, memory corruption, and sandbox escapes to deliver code, steal data, and pivot deeper into enterprise environments.

Exploiting Trust and Scale with Malicious Extensions

Even as browser providers improve extension vetting, threat actors are adapting to ensure their malicious add-ons get approved for purchasing. The compromise of reputable developer accounts and plugin supply chains now enable attackers to weaponize legitimate extensions, impersonate some of the most popular tools available, and harvest SSO tokens without being noticed. Once again, endpoint detection tools, VPNs, and other legacy solutions do not have the visibility or context needed to stop these malicious extensions from striking.

Session Hijacking and Beyond

Instead of relying on phishing alone to steal credentials, sophisticated hackers will hijack browser sessions and tokens. This is usually done through malicious JavaScript injected via compromised ad networks or shadow IT. Attackers will then bypass MFA and maintain ongoing access, even as passwords change. New drive-by malware tactics exploit zero-day flaws in rendering engines, leveraging modern ad supply chains as the point of entry. This masks C2 comms within encrypted browser traffic.

AI-Powered Social Engineering

Generative AI (GenAI) has changed the social engineering game, aiding cybercriminals to create hyper-personalized campaigns that bypass traditional detection methods. GenAI has given way to deepfake voice cloning and video calls that are being weaponized for business email compromise attacks. LLMs can scrape information off of social media to help craft convincing spear-phishing campaigns to impersonate employees or executives, making it extremely difficult to verify.

Cloud-Native Attacks

Attacks that hijack cloud identity tokens or abuse API access allow adversaries to exfiltrate sensitive data and maintain workflow persistence directly inside SaaS platforms. This means they can bypass legacy security solutions that only focus on the endpoint. Today's security tools must bring the SaaS environment into focus since the endpoint is no longer the main path of attack.

Why Legacy Security Tools Aren't Enough

Legacy solutions struggle to keep pace with today's adaptive and sophisticated browser-based attack techniques, driven in part by the growth in AI technology. This leaves critical blind spots in enterprise defenses. This section examines the inherent limitations of traditional tools in the context of browser security and browser-based attacks, as well as the urgent need for proactive approaches.

Gaps In Visibility

Traditional tools like EDR and SWG are still valuable, but their architecture leaves them blind to what happens inside the browser. As the browser becomes the new OS, those blind spots become entry points. Extension traffic, in-browser scripts, and stolen session tokens are basically invisible to those tools, and users running BYOD or unsanctioned browsers introduce risk that IT teams can't even manage.

Perimeter and Policy Limitations

SASE investments focus on access. But attackers operating within active sessions can bypass these controls. For example, Modern protocols can complicate SSL inspection and SWG policies. SWGs can also struggle to granularly govern how data is used once rendered. Finally, many SASE controls do reach unmanaged devices, leaving a critical blind spot.

Delayed Responses to New Threats

Legacy endpoint detection tools mainly rely on signature updates to detect and deter attacks. This signature-based reliance causes delays in detecting emerging attack methods or even evolving variants of known malware.

Limited SaaS and Cloud Integration

Legacy DLP, conventional firewalls, SWGs, and more often struggle to shore up the dynamic cloud-native work environment of today's enterprise. They lack the necessary APIs and contextual awareness needed to secure data and user activity beyond the perimeter.

What Security Leaders Can Do Next

The first step to take is modernizing your browser stack. Adopting a Secure Enterprise Browser (SEB) purpose-built for the AI age is a necessity. Moreover, a browser-agnostic solution architected for granular policy, the management of extensions, and real-time threat protection, without introducing user friction should top your list. Besides an SEB, enterprises can take the following steps to improve their security posture and brace for tomorrow's browser-driven threats:

1. Manage Extensions: Create allow-lists and conduct regular audits to ensure no risky extensions or abused legitimate extensions make their way onto your devices.
2. Zero-Day Focus: Encourage browser updates organization-wide for all managed devices so new patches can be utilized immediately.
3. Browser Audits: Make quarterly browser posture reviews a compliance requirement to catalog plugins and check for shadow SaaS.
4. Ongoing Education: Train your staff on the latest attack techniques and highlight the risks of malicious extensions and phishing.
5. Security + IT Partnership: Ensure business and IT coordinating on patch enforcement, extension policies, and more are applied to all company-owned and BYOD endpoints.

Final Thoughts: A New Frontier of Cyber Resilience

As browsers now define enterprise risk boundaries, attackers will keep evolving. Adversaries are now leveraging AI-generated extensions, exploiting trust, and innovating within trusted contexts. Organizations that make browser security a board-level agenda, prioritizing real-time visibility, removal of legacy blind spots, and reducing user friction will usher in the next era of cyber resilience. As we begin to look to 2026, one truth has become clear: security is now a browser problem. Those who address it with innovation will shape a safer digital future for us all.

To speak with a browser security expert or learn more about browser-agnostic Secure Enterprise Browser (SEB) solutions, click here.

About the Author: Suresh Batchu is the COO and a Co-founder of Seraphic. Before joining Seraphic, he co-founded MobileIron, which went public in 2014 and was later acquired by Ivanti in 2020. He also served as an investor, advisor, and board member for CloudKnox, which was acquired by Microsoft in 2021. Suresh holds an M.S. in Computer Science from the University of South Florida and holds 46 patents in the areas of Networking, Security, Identity, and Mobility.