Hazy Hawk: The Silent Hijacker Exploiting DNS Vulnerabilities

Hazy Hawk is a newly identified, highly persistent cyber threat actor that leverages weaknesses in Domain Name System (DNS) configurations—specifically dangling DNS records—to hijack subdomains of legitimate, high-profile organizations. Their activities demonstrate a growing trend in non-intrusive, infrastructure-based exploitation that bypasses traditional perimeter defenses.

By exploiting misconfigured or forgotten DNS entries, Hazy Hawk redirects traffic from trusted subdomains to malicious servers, where users are exposed to phishing, malware, scamware, and advanced redirection techniques.

How Hazy Hawk Operates: Step-by-Step Breakdown

1. DNS Reconnaissance and Target Identification

Hazy Hawk initiates its campaign by conducting automated scans to discover “dangling” CNAME records—DNS entries that still point to external services (like cloud storage, hosting platforms, or CDNs) which no longer exist.

• Example: A subdomain like downloads.healthgov.au may still point to a decommissioned AWS S3 bucket.
• These are often remnants of abandoned cloud projects or services that were shut down but never had their DNS cleaned up.

Technical Insight: A dangling CNAME record behaves like a broken pointer—once the original destination becomes available for registration again, anyone can claim it and thus gain control over that subdomain.

2. Resource Reclamation & Subdomain Takeover

Once a vulnerable CNAME is found, Hazy Hawk registers the corresponding cloud resource, instantly inheriting control over the associated subdomain.

• This allows them to serve malicious content from:
  secure.deloitte.com,
  updates.cdc.gov,
  app.healthgov.au,
  without ever compromising those organizations’ core systems.

Key Advantage: Traditional security solutions often trust subdomains from reputable parent domains, allowing malicious activity to pass undetected.

3. Traffic Monetization & Payload Delivery

With control over a trusted subdomain, Hazy Hawk employs a Traffic Distribution System (TDS) to:

• Redirect users to scams (e.g., fake lottery winnings, cryptocurrency giveaways)
• Deliver malware payloads (including Android APKs and Windows executable files)
• Harvest credentials via phishing pages disguised as Microsoft 365, Google, or financial services portals

Example: One hijacked CDC subdomain redirected visitors to download a fraudulent Android app laced with spyware.

Target Profile and Global Impact

These attacks exploit institutional trust—users are more likely to trust content when it originates from a known .gov, .edu, or major brand subdomain.

Why This Attack Vector Is So Effective

1. Non-Invasive and Stealthy

Hazy Hawk never breaches the actual infrastructure—they simply claim orphaned assets and use the organization’s DNS configuration against them.

2. High Credibility, High Impact

Hijacked subdomains lend immediate legitimacy to malicious campaigns, allowing higher success rates for phishing and malware infections.

3. Infrastructure-Based

These attacks don’t rely on zero-day exploits or endpoint vulnerabilities; instead, they exploit digital hygiene lapses, which often fall outside the scope of regular vulnerability scanning.

Mitigation and Defense Strategies

A. Proactive DNS Hygiene

• Audit DNS zones regularly to detect dangling or inactive records.
• Use tools like:
  • DNSDumpster
  • Detectify
  • Microsoft Defender for DNS
• Maintain an inventory of third-party services tied to DNS entries.

B. Cloud Resource Synchronization

• Automate decommissioning workflows to remove DNS records when cloud assets are deleted.
• Use infrastructure-as-code (IaC) practices to manage DNS in tandem with cloud deployments.

C. Continuous Monitoring

• Enable DNS logging and anomaly detection to identify traffic patterns that suggest unauthorized activity.
• Set alerts for unusual activity on subdomains, especially those tied to deprecated services.

D. Incident Response Readiness

• Include DNS exploitation scenarios in tabletop exercises.
• Create playbooks for subdomain hijack response, including:
  • Notification to affected users
  • Takedown procedures with cloud vendors
  • Public disclosure, if necessary

Strategic Takeaway

Hazy Hawk represents a new breed of threat actors: patient, observant, and infrastructure-aware. Their campaigns prove that even without breaching firewalls or endpoints, attackers can gain a foothold through neglected digital real estate.

For organizations of all sizes, the lesson is clear: Cybersecurity is not just about protecting what’s running—it’s also about cleaning up what’s not.