Crosslayer Labs: Defending the Internet Stack

In an era where nearly every aspect of business depends on the Internet, the security of websites and APIs has become mission-critical. Yet the tools used to protect digital infrastructure have not always kept pace with the sophistication of modern cyber threats. Crosslayer Labs emerged in 2025 to address this widening gap. Founded in San Francisco and backed by Y Combinator’s Winter 2026 batch, the startup set out with a clear mission: to protect organizations from a new class of attacks capable of impersonating legitimate websites and services without detection.

Crosslayer Labs focuses on what it calls “outside-in” monitoring — a fundamentally different approach to cybersecurity. Instead of only analyzing internal logs and defenses, the company examines how an organization’s infrastructure appears from the broader Internet. This perspective allows it to detect subtle manipulations across DNS records, routing systems, certificate issuance, and other layers that attackers increasingly exploit.

The founding team’s pedigree is unusual even by Silicon Valley standards. These are not simply experienced engineers; they are researchers whose prior work shaped the modern Internet’s security foundations. Their invention of the Multi-Perspective Issuance Corroboration (MPIC) standard — now used globally to secure HTTPS connections — positioned them uniquely to identify weaknesses in the very systems they helped create.

The startup’s premise is both alarming and compelling: even websites displaying the familiar lock icon may not be safe. Crosslayer Labs aims to ensure that organizations can trust not only their internal defenses but also the integrity of the global infrastructure on which their digital presence depends.

What Problem Does Crosslayer Labs Aim to Solve?

The problem Crosslayer Labs addresses is subtle but devastating. Traditional cybersecurity strategies focus on preventing intrusions into servers or applications. However, attackers have increasingly shifted toward manipulating the infrastructure that directs users to those services in the first place.

Consider a scenario where a user attempts to visit a legitimate company website. Unknown to them, sophisticated attackers have manipulated Internet routing or domain infrastructure to redirect traffic to a malicious replica. The browser may still display a valid TLS certificate and lock icon, creating a false sense of security. By the time the deception is discovered, sensitive data — credentials, financial information, proprietary assets — may already be compromised.

Such attacks exploit weaknesses across multiple layers of the Internet stack: DNS poisoning, BGP hijacking, certificate misissuance, and malicious JavaScript injection. Individually, these vulnerabilities have existed for years. What has changed is attackers’ ability to orchestrate them simultaneously, making detection extremely difficult.

Crosslayer Labs argues that the industry has lacked a unified solution capable of monitoring these dependencies holistically. Organizations often rely on separate tools for domain management, certificate tracking, network monitoring, and application security. This fragmentation creates blind spots — precisely where attackers operate.

By discovering and monitoring all Internet dependencies tied to a domain, Crosslayer Labs seeks to close those gaps. Its system correlates signals across layers, identifying patterns that would otherwise appear unrelated. The result is early detection of impersonation attempts before they escalate into full-scale breaches.

How Does the Crosslayer Approach Work?

At the heart of Crosslayer Labs’ platform is a cross-layer analysis engine designed to observe the Internet as a complex, interconnected system rather than a collection of isolated components. The platform continuously maps an organization’s external dependencies — DNS configurations, routing paths, TLS certificates, third-party scripts, and more.

This “outside-in” model allows the company to detect anomalies that internal monitoring cannot see. For example, a sudden change in routing announcements or certificate issuance behavior might signal an attempt to impersonate a domain. Individually, these events could appear benign. Together, they may reveal a coordinated attack.

The platform’s alerts are designed to be actionable rather than merely informative. Each alert includes root cause analysis and recommended remediation steps, enabling security teams to respond quickly. This emphasis on usability reflects the founders’ understanding that security solutions must integrate seamlessly into real-world operations.

Another distinguishing feature is the platform’s ability to discover previously unknown dependencies. Many organizations underestimate how many external services their websites rely on — content delivery networks, analytics scripts, authentication providers, and more. Each dependency represents a potential attack vector. Crosslayer Labs continuously inventories these elements to maintain an accurate threat model.

By correlating data across the entire Internet stack, the company aims to detect impersonation attacks that bypass conventional defenses. The approach represents a shift from reactive incident response to proactive infrastructure protection.

Who Are the Founders Behind the Technology?

Crosslayer Labs’ credibility rests heavily on its founding team, whose academic and industry achievements are deeply intertwined with the evolution of Internet security.

Henry Birge-Lee is widely recognized for his work on web and network security. As the inventor of MPIC, he addressed a critical vulnerability in how TLS certificates are issued — a breakthrough that now protects billions of secure connections daily. His research has influenced certificate authority practices worldwide and contributed to the adoption of DNSSEC by major providers.

Grace Cimaszewski brings expertise in web public key infrastructure and certificate security. Her doctoral research at Princeton helped map the attack surface of millions of websites, shaping how MPIC was implemented across the ecosystem. Her collaborations with industry leaders demonstrated an ability to translate academic insights into practical standards.

Prateek Mittal, a professor at Princeton University, is a prominent figure in cybersecurity and privacy research. His contributions extend beyond web security to the protection of artificial intelligence systems, including large language models deployed at scale. His work has earned numerous prestigious honors and influenced both academia and industry.

Together, the trio represents a rare combination of theoretical insight and practical impact. They are not merely responding to emerging threats — they helped define the technologies attackers now attempt to exploit. This perspective enables them to anticipate vulnerabilities before they become widespread.

Why Is Impersonation the Next Frontier of Cyber Threats?

Impersonation attacks represent a shift from breaching systems to deceiving users and infrastructure. Instead of hacking into a company’s servers, attackers manipulate the pathways that connect users to those servers. The result is a form of digital identity theft at the infrastructure level.

This strategy is particularly effective because it exploits trust mechanisms built into the Internet. Users rely on domain names, certificates, and routing systems to verify authenticity. When those mechanisms are compromised, traditional defenses offer little protection.

The rise of cloud computing and third-party services has further complicated the landscape. Modern websites depend on distributed infrastructure spanning multiple providers and geographic regions. Each component introduces potential vulnerabilities that attackers can exploit.

Crosslayer Labs argues that impersonation attacks will become increasingly common as cybercriminals seek high-impact methods with lower detection risk. By targeting infrastructure rather than applications, attackers can bypass many security controls and remain undetected for longer periods.

The company’s research suggests that TLS certificates alone can no longer guarantee authenticity — a startling conclusion given how central HTTPS has become to Internet trust. This realization underscores the need for new verification mechanisms capable of detecting cross-layer manipulation.

What Makes Crosslayer Labs’ Solution Unique?

Several factors differentiate Crosslayer Labs from traditional cybersecurity providers. First is its holistic perspective. Rather than specializing in a single layer — network security, application security, or endpoint protection — the company addresses the interactions between layers.

Second is its emphasis on discovery. Many organizations lack visibility into their full Internet footprint. Crosslayer Labs’ platform continuously identifies dependencies and relationships that may otherwise go unnoticed.

Third is the founders’ direct involvement in creating the standards they now monitor. This insider knowledge provides an advantage in identifying edge cases and emerging vulnerabilities.

Finally, the company focuses specifically on impersonation and hijack attacks, a niche that has received relatively little attention compared to ransomware or data breaches. By concentrating on this domain, Crosslayer Labs positions itself as a specialist in a rapidly growing threat category.

What Could the Future Hold for Crosslayer Labs?

As digital infrastructure becomes more complex, the need for comprehensive monitoring will only increase. Crosslayer Labs envisions a future where organizations treat Internet presence integrity as a core security requirement rather than an optional safeguard.

The startup’s technology could evolve into a foundational layer of Internet defense, similar to how antivirus software became standard on personal computers. Its research-driven approach suggests ongoing innovation as new attack techniques emerge.

Potential applications extend beyond corporate security. Governments, financial institutions, healthcare providers, and critical infrastructure operators all rely on trustworthy digital communication channels. Protecting these systems from impersonation could have far-reaching societal implications.

The company’s participation in Y Combinator indicates strong investor confidence, but its ultimate success will depend on execution — translating groundbreaking research into scalable, user-friendly products.

Why Does Crosslayer Labs Matter Now?

The timing of Crosslayer Labs’ launch reflects a broader shift in cybersecurity priorities. As organizations strengthen internal defenses, attackers are increasingly targeting the external systems that connect users to services. The battlefield has moved outward, into the fabric of the Internet itself.

Crosslayer Labs represents an attempt to secure that frontier. By monitoring infrastructure dependencies and correlating signals across layers, the company aims to restore trust in digital interactions.

In a world where a single successful impersonation attack could drain financial accounts, compromise sensitive data, or disrupt critical services, the stakes are immense. Crosslayer Labs’ work highlights a fundamental truth: protecting the Internet requires understanding it as an interconnected ecosystem.

If the startup succeeds, it may redefine how organizations think about cybersecurity — not as a perimeter to defend, but as a network of relationships to continuously verify.