Stop Broken Link Hijacks at the DNS Layer with Advanced DNS Security

[JayGolf]

This blog was written by Gokul Pokuri, Sr. Product Manager

In a world of SaaS and digital collaboration, your security posture is only as resilient as the weakest link in your external resource chain. While most focus remains on direct phishing or known malicious infrastructure, a silent threat is gaining momentum: Broken Link Hijacking.

Today, we are announcing a Industry-first capability for Advanced DNS Security (ADNS): Proactive detection and mitigation of Dangling Web and App domains.

The Invisible Threat: Anatomy of a Dangling Domain

Modern websites and applications are complex webs of interconnected dependencies, frequently linking to third-party support forums, academic archives, or promotional sub-domains. When these external domains expire while the links remain active on legitimate business sites, a critical vulnerability is created: the assets become 'dangling'.

Threat actors exploit these 'dangling' links by re-registering expired domains to host malicious payloads. Because the initial link resides on a "trusted" site, traditional security measures often fail to intervene.

Key Attack Vectors:

• Broken Link Hijacking: Attackers take control of expired or claimable domains to redirect users to malicious content.
• Impersonation & Phishing: Expired support forums, email domains, and promotional domains are re-registered to harvest credentials or serve offensive content to unsuspecting employees.
• Cross-site Scripting (XSS): Dangling assets allow attackers to inject malicious scripts directly into the victim's browser session. By re-registering a domain that hosts a legacy JavaScript library, a threat actor can execute unauthorized code within the context of the "trusted" parent site. Dangling domains in security headers can also be claimed to bypass security controls. This allows hackers to silently steal login cookies, record keystrokes, or hijack user sessions.

Why Traditional Solutions Fall Short

Traditional security models often place the burden of link hygiene on webmasters or rely on reactive tools that miss the window of exploitation:

• Vulnerability Scanners: While they can identify broken links, they don't protect the end-user in real-time if a link is weaponized between scans.
   
• Static Block lists: These are fundamentally reactive and often fail to catch a domain the moment it is re-registered by an adversary.
  
  
• Manual Monitoring: This is unscalable for the thousands of external resources a distributed enterprise interacts with daily.

The ideal approach must protect the end-user at the DNS layer, before a network connection is ever established.

How does Palo Alto Networks Precision AI™ help identify, detect, and Block Broken Link Hijacks

Palo Alto Networks’ Advanced DNS security is the first to introduce a novel detection capability specifically designed to neutralize these threats before a network connection is ever established. By moving protection to the DNS layer, we fill the critical gap left by reactive solutions. 

How it works

The Advanced DNS Security service uses Precision AI™ to analyze domain registration data alongside DNS query patterns and various attributes. If a user clicks a "trusted" link that points to a expired/claimable domain, the DNS query is intercepted and blocked in real time before any TCP/IP handshake or TLS negotiation occurs.

Implementation Specifications

When will Dangling Web and App detection be Available?

We are pleased to announce that the Dangling Web and App detection is released on January 29, 2026 as part of the Grayware Domains. 

 

What Action Is Needed to Benefit from Dangling Web and App Detection?

Customers do not need to make any configuration changes unless they wish to modify the default or configured action of the Grayware Domains category. Dangling Web and App detection is categorized as Grayware, and the default action for this category is set to block.

 

What is the Threat ID and Threat Name for the Dangling Web and App category?

This new detection capability categorizes these threats as Dangling Web and App

• Threat ID: 109,002,007
• Default Action: Block
• Threat Name: Dangling_web_and_app:<FQDN>

Does Palo Alto Networks Have A Test Domain for the New Dangling Web and App  Category?

Yes. To facilitate testing and familiarization with the new detection capability, we have included a test domain 

Test Domain: test-dangling-web-and-app.testpanw.com

What is the sample threat log entry for dangling web and app detection: 

Below are the snippets of how Dangling Web and App detection entries appear in the threat log of the NGFW and SCM Log Viewer:

Looking to simplify DNS security and extend protection across your entire environment? Contact your Palo Alto Networks representative or visit our Advanced DNS Security page to get started.

For a detailed configuration guide, please refer to the Technical Documentation.