Right now, code is executing in your users’ browsers that your WAF has never inspected, your DAST never tested, and your pen testers never touched. It’s not a gap in your tools, it’s a gap in where those tools look. And attackers have already found it.

●      SAST and DAST to secure code

●      EASM to identify exposed assets

●      WAFs and bot mitigation to protect applications

●      Regular penetration testing to validate risk

These controls have done their job well. But the application has moved. More of it now runs in the browser, shaped by a constantly changing ecosystem of third and fourth-party dependencies that these tools were never designed to see.

In many environments, this browser layer remains largely unmeasured. That is where web supply chain risk lives, and it is the front line security teams can no longer afford to ignore.

The Expansion of the Attack Surface

To support modern development and release cycles, applications rely heavily on a network of third and fourth-party technologies. Each introduces code that executes directly in the user’s browser, code the organisation did not write and often cannot see. Reflectiz research across 4,700 websites found that 64% of third-party applications access sensitive data without a clear business justification. Common examples include:

●      Tag managers and marketing platforms

●      Analytics and tracking technologies

●      Embedded services and integrations

●      Payment providers (e.g., Afterpay, Zip, Stripe)

The problem is not the vendors themselves, it is the lack of visibility into what they are actually doing at runtime.

Where Traditional Visibility Breaks Down

Most organisations have a clear view of what they build and deploy, but far less understanding of what actually executes in a real user session.

These controls operate outside the browser layer. The result is a gap between known vendors and actual runtime dependencies, and that is exactly where web supply chain risk sits.

The Rise of Web Supply Chain Risk in ANZ

This gap is becoming more critical as attackers move away from hardened infrastructure toward:

●      Third-party script compromise

●      Dependency hijacking

●      Data exfiltration through browser-executed code

This is not theoretical. High-profile web skimming attacks, including incidents affecting major airlines, ticketing platforms, and retail brands globally, followed exactly this pattern: attackers compromised a trusted third-party script, injected malicious code into payment flows, and exfiltrated card data for months before detection. Traditional controls generated no alerts, because the attack never touched the infrastructure those controls monitor.

The Regulatory Stake

In Australia, the stakes have never been higher. The OAIC is increasingly focusing on how data is collected and handled in the browser. As outlined in Reflectiz’s analysis, misconfigured trackers can expose sensitive user data, with potential penalties reaching up to AUD $50 million or more.

Organisations are now strictly accountable for:

1. What data is collected in the browser.
2. Whether that aligns with user consent.
3. Exactly where that data is being sent.

From Visibility to Context: The Next Phase of Attack Surface Management

Knowing what assets you have is no longer enough. The question security teams need to answer is: what are those assets doing? For web applications, that question cannot be answered from outside the browser. It requires continuous observation of what scripts are executing, what data they are touching, and where that data is going, in real user sessions, not synthetic scans.

This is the gap that Continuous Threat Exposure Management (CTEM) frameworks are designed to close, and the browser is where that gap is most acute for organisations operating modern web applications.

Bringing the Browser into Scope

ANZ organisations are already navigating this. Village Roadshow needed visibility across hundreds of client-side scripts to demonstrate PCI DSS compliance, a requirement that cannot be met by server-side tools alone. Lion faced the challenge of managing browser-side risk across a complex, distributed environment spanning multiple brands and teams. In both cases, the answer started with getting visibility into what was actually running in the browser.

To manage the web supply chain in practice, you must be able to:

●      Continuously observe script execution across key user journeys.

●      Identify when script behaviour changes in meaningful ways.

●      Map data flows across third and fourth-party dependencies.

Final Thought

Modern web applications run on a shadow supply chain, dozens of third and fourth-party scripts executing in real user sessions, largely invisible to conventional security controls. The organisations that close this gap will not just reduce risk; they will be better positioned to meet the compliance and privacy obligations that regulators are increasingly enforcing. The ones that don’t are operating with an unknown variable at the heart of their application risk. It’s time to bring the browser into scope.

Luke Joas leads ANZ for Reflectiz, helping Australian and New Zealand enterprises secure their web supply chains and stay ahead of evolving privacy regulations. Reflectiz recently opened its Sydney office at Level 13, 333 George Street. Luke welcomes a conversation — reach him at [email protected].

The post Web Supply Chain Risk in ANZ: Why the Browser is the New Front Line appeared first on Reflectiz.

*** This is a Security Bloggers Network syndicated blog from Cybersecurity Blog: News, Insights and Research – Reflectiz authored by Luke Joas. Read the original post at: https://www.reflectiz.com/blog/supply-chain-anz/