In the ever-evolving landscape of cybersecurity, threats emerge, shift, and sometimes fade. However, one vulnerability class  subdomain takeovers has steadily grown from a niche concern into a significant organizational risk over the past decade. What started as a technical discussion about "dangling DNS" among researchers is now a frequent finding with potentially severe consequences. This article explores the historical trajectory, financial implications, and current prevalence of subdomain takeover vulnerabilities from 2015 to 2025.

 🧠 From Obscurity to Mainstream: The Rise of Subdomain Takeovers

The mid-2010s saw subdomain takeovers as a relatively obscure issue, primarily discussed by bug bounty hunters and security researchers. However, this began to change rapidly.

• Late 2010s: Reports of hijacked subdomains affecting major corporations became more common. Bug bounty platforms like HackerOne and Bugcrowd saw a steady increase in submissions related to this vulnerability class year after year. Academic research between 2016-2019 validated this trend, highlighting it as an emerging risk rather than a theoretical edge case. For instance, a study analyzing HackerOne data confirmed consistent year-over-year growth in disclosed takeover reports from 2014 through 2018.
• Early 2020s: The problem escalated further. Industry surveys started noting double-digit percentage growth in subdomain-related vulnerabilities. Security firm Detectify, for example, reported a significant 25% increase in detected subdomain takeover weaknesses from 2020 to 2021 alone. They also observed that the median number of vulnerable subdomains per domain had doubled compared to the previous year.

This trajectory clearly shows that what began as a subtle cloud misconfiguration has transformed into a common security gap impacting organizations of all sizes.

💸 The Growing Financial and Business Fallout

Initially, many subdomain takeovers were identified by researchers before significant damage occurred, often resulting in modest bug bounty payouts (like the $2,000 paid by Starbucks in 2018 for an Azure-based subdomain). However, when attackers successfully exploit these vulnerabilities, the consequences can be far more severe:

• Financial Losses: Attackers leverage the trust associated with a legitimate domain. Hijacked subdomains are used for phishing campaigns that steal customer credentials or distribute malware, leading to direct financial fraud. While not a subdomain takeover itself, a 2024 attack using a lookalike domain targeting a freight logistics platform resulted in estimated losses of $50,000–$200,000 in a single scam, demonstrating the financial power of domain impersonation. Similar phishing attacks via hijacked subdomains of banks or e-commerce sites can lead to substantial losses, potentially requiring reimbursement and incurring regulatory fines.
• Brand and Reputational Damage: Public incidents erode trust. The defacement of a subdomain associated with the Joe Biden presidential campaign in 2020 generated negative press. Similarly, revelations that tech giants like Microsoft had hundreds of unprotected subdomains (over 670 found by one researcher in 2020) raised questions about their security posture.
• Regulatory and Legal Consequences: If a subdomain takeover leads to a data breach (e.g., through cookie theft or API key exposure), organizations face potential penalties under data protection regulations for failing to adequately secure their digital assets.

🏢 Which Industries Are Most Affected?

While no sector is immune, certain industries have shown particular vulnerability:

• Technology and Cloud Services: Companies deploying numerous microservices and dynamic environments often struggle with DNS hygiene. The Microsoft example (670+ vulnerable subdomains) highlights the scale of the challenge even for tech leaders.
• E-commerce: Often reliant on third-party platforms, retail brands are frequent victims. One internet-wide scan found that a staggering 62% of all vulnerable DNS records identified pointed to Shopify storefront domains.
• Government and Finance: Although often having stricter controls, these sectors are not immune. Researchers found approximately 200 potentially vulnerable U.S. government (.gov) subdomains and instances where bank subdomains were hijacked for phishing campaigns.

An alarming study in 2020 scanning the Alexa Top 1000 global websites found 139 potential subdomain takeovers, suggesting roughly 14% of the world's most popular sites harbored this weakness at the time.

📊 The Current State (2024-2025): A Persistent Problem

Despite increased awareness, subdomain takeovers remain prevalent.

• Widespread Exposure: Recent scans continue to uncover vast numbers of dangling DNS records. A RedHunt Labs study identified over 424,000 vulnerable subdomains across 220 million scanned domains, affecting organizations ranging from small businesses to global enterprises. Their findings included vulnerabilities within the Alexa Top 1000, prestigious universities (~1,000 .edu candidates), and government agencies (~200 .gov candidates)

• The Monitoring Gap: A major reason for persistence is the lack of continuous DNS monitoring. Attackers and bug hunters often use automated tools to find dangling records within minutes of them becoming vulnerable. Most organizations, however, lack robust processes to track DNS entries associated with decommissioned services. This "digital drift" is a significant blind spot.

• Large Organizations Still Struggle: Even Fortune 500 companies with extensive resources grapple with managing their vast subdomain portfolios. The complexity of sprawling infrastructure makes comprehensive asset inventory a monumental challenge. Attack surface management (ASM) tools are increasingly used, but vulnerabilities continue to emerge as cloud infrastructure evolves rapidly. Detectify noted that takeovers grew 20% faster than their customers' overall attack surfaces, indicating the problem is outpacing mitigation efforts for many.
  
   

   

Credits 

• Hackerone
• Microsoft
• Detectify
• RedhuntLabs