Category: Malware Delivery
Malvertising in the browser
Malvertising is when malicious ads deliver scams, phishing, or malware—often by redirecting users to a harmful site after a click (or sometimes on ad load).
Quick answer
Ad networks and real websites can become involuntary distribution channels, so even “normal browsing” can lead to credential theft or malware delivery.
For drive-by content and risky downloads, isolation keeps untrusted web execution off the endpoint and makes each browsing session disposable.
When you need this
- You’ve seen indicators of this threat in your environment.
- Users frequently click unknown links as part of daily work.
- You need a control that reduces risk without relying on perfect user judgment.
Last updated
2026-01-29
How it usually happens in the browser
- An attacker buys ads or compromises an ad supply chain to insert malicious creatives or scripts.
- Users click an ad (or the ad triggers a redirect in some scenarios).
- The browser is redirected to a phishing page, scam checkout, fake support page, or an exploit/download prompt.
- Attackers rotate domains frequently to evade blocklists and keep campaigns live.
What traditional defenses miss
- Reputation changes fast: a domain can be clean yesterday and malicious today.
- Malicious ads can appear on reputable sites, bypassing “only visit trusted sites” guidance.
- Ad-blocking helps but is inconsistent in enterprise environments and can break workflows.
How isolation changes the game
- Isolation contains ad-driven browsing away from endpoints, reducing exposure to exploit and download payloads.
- Disposable sessions limit persistent tracking and reduce session residue from ad networks.
- Policy can force high-risk traffic sources (ads, free content sites) into isolation without blocking them entirely.
Operational checklist
- Force ad-click traffic and high-risk content categories into isolated sessions.
- Block downloads and notification prompts in isolated sessions by default.
- Use DNS/web filtering to reduce exposure to known malicious ad domains; treat it as additive, not sufficient.
- Ensure incident response can capture the full redirect chain when an ad leads to harm.
- Pilot with teams that rely on ads/search (sales, recruiting) and measure usability impact.
FAQs
Can malvertising happen on reputable sites?
Yes. Reputable sites often use third-party ad networks, and malicious ads can slip in or appear intermittently.
Is malvertising only about malware?
No. It can drive phishing, scams, fake support, and other fraud—not just executable malware.
Do ad blockers solve this?
They help, but they’re not a complete enterprise control and can break sites. Isolation reduces impact when ads still slip through.
Why isolate ads instead of blocking them?
Many teams need ad-driven workflows (research, marketing). Isolation lets you keep productivity while reducing endpoint risk.
References
- Google Safe Browsing — Google
- Cloudflare: Browser Isolation — Cloudflare