A dangling Domain Name System (DNS) record is essentially an outdated or “orphan” DNS record pointing to a nonexistent website or service. It’s like an old phone book listing for a company that moved, thus providing the wrong information.

DNS records are entries in an extensive Internet directory, linking a website’s domain name (e.g., techslang.com) to a computer-readable IP address (e.g., 123.456.78).

Dangling DNS records emerge when websites or web services shut down or change, but their DNS records aren’t updated. This occurrence can be dangerous because attackers can take advantage of outdated records to send visitors to fake websites that steal information or install malware, potentially enabling them to launch more nefarious cyber attacks. As such, a dangling DNS record contributes to an organization’s attack surface.

Read More about a Dangling DNS Record

To better understand what a dangling DNS record is, let us first define what DNS records are.

What Are DNS Records?

The DNS is a fundamental component of the Internet’s infrastructure. DNS records translate human-readable domain names like techslang.com into machine-readable IP addresses like 123.456.78. This translation process allows users to access websites easily without memorizing complex numerical sequences.

Since they play a critical role in how the Internet works, DNS records are important digital assets. They come in several types, depending on the data stored in each. They are:

  • A record: Maps a domain name to an IPv4 address (e.g., techslang.com points to 123.456.78).
  • AAAA record: Maps a domain name to an IPv6 address.
  • Canonical name (CNAME) record: Creates an alias for a domain name, pointing it to another domain name (e.g., www.techslang.com may be a CNAME for techslang.com).
  • Mail exchange (MX) record: Specifies MX servers for handling email delivery for a domain.
  • Name server (NS) record: Identifies the authoritative NSs responsible for a specific domain.

What Is an Example of a Dangling DNS Record?

Each of the DNS record types listed above can become dangling. However, the most common type of dangling DNS record is an A record since it is the most basic and widely used DNS record type.

An example of a dangling A record emerges when a company decides to close an online store with a domain name like example[.]com that points to the IP address 192[.]123[.]4[.]10. If the owner forgets or neglects to update the concerned DNS record, the A record pointing to the old IP address becomes dangling. This orphaned record remains in the DNS even though the website no longer exists in that location.

Example of a dangling DNS record

A user trying to visit the website may see an error message. However, attackers can exploit dangling A records. They can set up a malicious website at the IP address listed in the outdated record.

How Do You Identify a Dangling DNS Record?

Website administrators can identify dangling DNS records through these methods.

  • DNS monitoring tools: Several online DNS monitoring tools can proactively scan for DNS misconfigurations, inconsistencies, and potential dangling records.
  • Attack surface management (ASM) platforms: ASM solutions have built-in asset discovery capabilities that can identify and monitor an organization’s DNS records.
  • Manual external DNS lookups: Manual checks can be performed using online DNS lookup tools. These tools allow users to query the DNS for a specific domain name and see which IP address it resolves to. Users can then verify if their domains point to the same IP addresses where websites are hosted. Any discrepancy may indicate a dangling record.
  • Scheduled DNS audits: Organizations typically integrate regular DNS audits into their website maintenance routine. These audits involve thoroughly reviewing all DNS records, including A, MX, and any subdomain records an organization may have.

Why Are Dangling DNS Records Dangerous?

Dangling DNS records pose a significant security threat because they create security weaknesses that cyber attackers can exploit. Here are some potential consequences of having dangling DNS records:

  • Website hijacking
  • Sensitive data theft
  • Malware distribution
  • Spamming
  • Subdomain takeover
  • Service disruption

We’ll discuss each of these in detail.

Website hijacking 

This is the most common and potentially damaging consequence. Attackers can set up a malicious website at the IP address listed in the dangling record. When someone tries to visit a legitimate website (using the domain name), the DNS record redirects them to the attacker’s site instead.

Sensitive data theft

The attackers’ fake websites are often disguised as legitimate login pages for banks, social media platforms, or online stores. These websites trick users into entering their usernames, passwords, bank details, and other sensitive information.

Malware distribution

Malicious websites associated with dangling DNS records may contain hidden code that automatically downloads malware onto visitors’ computers without their knowledge. This malware can damage files, steal data, or even take control of an entire system.

Spamming

Attackers may use compromised websites to send out spam or launch phishing attacks against unsuspecting users.

Subdomain takeover

A subdomain takeover occurs when an attacker gains control of a subdomain’s DNS record, typically by exploiting a misconfigured or inactive DNS record the subdomain uses.

Service disruption

Dangling DNS records can sometimes disrupt legitimate services associated with a domain name. For example, a dangling MX record can prevent emails from getting delivered to an intended recipient.

Dangling DNS records are like outdated addresses on the Internet’s map. They can lead users to fake websites that steal information or install malware. However, keeping DNS records updated and using website security tools can help organizations avoid these dangers and protect website users from online threats.

Key Takeaways