Call it what you will—the internet’s phone book, address book, or GPS—the Domain Name System (DNS) is how we find our way online. Without it, internet navigation would grind to a halt, which is why it’s a prime target for cyberattacks.
DNS attacks are a category of cybersecurity threats aimed at exploiting vulnerabilities within the DNS infrastructure. From overwhelming DNS servers with Distributed Denial of Service (DDoS) attacks to sneaking in illicit code through DNS Tunneling, malicious actors deploy various tactics to compromise data security and availability. Each method poses unique challenges to network administrators and IT security teams tasked with safeguarding their systems.
What Is a DNS Attack?
DNS translates easy-to-remember domain names into IP addresses, allowing users to reach websites without memorizing long strings of numbers or complex hexadecimal codes. Because nearly all internet activity relies on DNS, it’s a prime target for cyberattacks. By exploiting vulnerabilities in DNS, malicious actors can disrupt services, redirect users to websites they control, run phishing campaigns, deliver malware, or steal sensitive data. Some attacks, such as cache poisoning or DNS hijacking, manipulate the resolution process. In contrast, others, like DNS Amplification attacks, can make websites and applications unreachable, halting business operations entirely.
The consequences can be severe: prolonged outages that damage brand reputation, loss of sensitive business or customer information, and damage to user trust. In some cases, DNS compromise is used as a stepping stone for deeper intrusions into the network.
What Are Some Common Types of DNS Attacks?
To execute DNS attacks, malicious actors often use a combination of tactics, making them more destructive and, in some cases, harder to detect or block. Mitigating this risk requires understanding the most common attack types, recognizing their warning signs, and building resilient DNS infrastructure.
DNS Amplification Attacks
DNS amplification is a specific type of DDoS attack that exploits the size difference between a small DNS query and a much larger DNS response. Malicious actors send small queries with spoofed source IP addresses to vulnerable open resolvers. These resolvers respond with much larger DNS replies, flooding the target with data. Because DNS queries can generate responses dozens of times larger than the original request, attackers can amplify their traffic by factors of 30–50x or more, consuming network bandwidth with minimal resources.
For end users, the result is the same: the website, application, or service becomes inaccessible. DNS amplification is usually easy to detect at the network level due to the sudden spike in DNS traffic, but stopping it requires preemptive defenses such as rate limiting, blocking spoofed traffic, and securing or disabling open resolvers. Publicly accessible DNS servers are frequently abused in these attacks, making it critical to restrict resolver access and follow secure configuration practices.
DNS Hijacking
Domain Name System (DNS) hijacking, also known as DNS redirection, is a type of attack in which DNS queries are manipulated to redirect users to malicious websites. To execute these attacks, attackers may compromise DNS servers, alter DNS records, modify router settings, or deploy malware on endpoint devices to change DNS configurations.
While the primary goal is often to steal sensitive information through phishing pages, DNS hijacking can also be used to deliver malware, display unwanted ads, or block access to legitimate sites. The redirected sites are typically convincing replicas of trusted destinations, making it easy for victims to unknowingly enter login credentials, payment information, or other sensitive data.
In some cases, malicious actors don’t compromise DNS servers at all. Instead, they hijack the routes that DNS queries take to reach them. By exploiting weaknesses in the Border Gateway Protocol (BGP), they can announce false network paths, redirecting DNS traffic through their own infrastructure. Once in control of the traffic, attackers can intercept or modify DNS responses before forwarding them on, enabling redirection without interacting with the DNS server itself.
DNS Tunneling
DNS tunneling attacks allow malicious actors to embed data within seemingly legitimate DNS queries, exploiting the protocol to create covert communication channels or exfiltrate information from compromised systems. Because DNS traffic is often trusted and rarely inspected in depth, this hidden data can travel alongside normal queries without detection.
DNS tunneling creates covert channels for data exfiltration or command-and-control (C2). Malicious actors embed payloads inside DNS queries and responses, enabling compromised systems to communicate with attacker-controlled servers. For tunneling to succeed, a compromised device typically needs access to an internal DNS resolver that can forward queries to external nameservers, providing a pathway for malicious traffic to leave the organization.
Detecting these attacks requires scrutinizing DNS traffic for anomalies such as abnormal query volume, unusual payload sizes, suspicious domain names, or unexpected DNS record types.
DNS Spoofing/ DNS Cache Poisoning
DNS spoofing is a broad category of attack, and DNS cache poisoning is one specific method used to carry it out.
With DNS spoofing attacks, malicious actors corrupt cached answers on DNS servers and redirect users to websites under their control. In contrast, DNS cache poisoning attacks are a type of spoofing attack where a malicious actor inserts forged DNS records into a resolver’s cache. This causes the resolver to return incorrect IP addresses, redirecting users to malicious websites without their knowledge. Attackers exploit weaknesses in DNS software or insufficient validation to inject these false records. Once a cache is poisoned, it will continue serving the incorrect data until the cache is cleared or the record expires. Both DNS spoofing and DNS cache poisoning attacks are used to capture sensitive data by sending victims to convincing fake login pages or malware delivery sites.
DNS Reflection
DNS reflection attacks use open or misconfigured DNS servers to direct massive traffic floods toward a target. Malicious actors send DNS queries with a spoofed source IP address, causing the servers to send their responses to the victim instead of the real sender. When these queries are crafted to trigger disproportionately large responses, the reflection is combined with DNS amplification, dramatically increasing the attack’s impact.
This pairing enables malicious actors to utilize minimal bandwidth while generating enormous traffic volumes, thereby overwhelming the victim’s network and services. While the DNS servers themselves remain uncompromised, they are unwitting participants in the attack.
Domain Generation Algorithm (DGA) Attack
Domain Generation Algorithm (DGA) attacks use algorithms to rapidly create large numbers of domain names, often dozens or hundreds per day. Malicious actors use these domains to help malware or botnets maintain communication with C2 servers. By constantly changing domains, they evade blocklists and sustain operations even if some domains are seized or shut down. Each generated domain is a potential connection point, complicating takedown efforts and detection. DGAs are a common resilience technique for botnets, malware distribution, and data exfiltration campaigns.
DNS Rebinding
DNS rebinding tricks a user’s browser into interacting with malicious domains as if they were legitimate ones. This type of DNS attack is used to bypass security restrictions and access internal networks.
First, malicious actors lure users to a site they control, often through phishing, ads, or embedded scripts. That site’s domain initially resolves to an IP address under the malicious actor’s control, allowing them to serve harmful JavaScript. Shortly afterward, the domain “rebinds” to an internal or private IP address. The injected script can then relay commands through the user’s browser to services inside the firewall, enabling data theft, unauthorized access, or network reconnaissance.
DNS Spoofing
DNS spoofing deceives users about the legitimacy of web destinations. When a user types a website name into their browser, DNS translates the domain name into an IP address so the browser knows where to connect. In a spoofing attack, the browser is fed false directions, redirecting users to a malicious lookalike site that appears completely legitimate.
This attack works by corrupting the DNS resolution process, tricking resolvers or their caches into accepting forged responses, unlike DNS hijacking, which tampers directly with authoritative DNS records. DNS spoofing is most often used in phishing campaigns and data theft, typically through techniques like DNS cache poisoning or man-in-the-middle (MitM) attacks.
Fast-flux DNS
Fast flux DNS attacks see attackers rapidly rotating IP addresses, and even entire Autonomous System Numbers (ASNs) associated with a malicious domain to avoid detection, evade blocklists, and prolong the domain’s lifespan. By constantly changing the IP addresses linked to a domain, attackers make takedown efforts more challenging and complicate tracking, evading security measures designed to block access. This technique is especially common among phishing operations, botnet C2 networks, and malware distribution campaigns.
When a domain suddenly starts resolving to different ASNs or IP ranges in quick succession, it’s often a strong indicator of fast-flux activity. Defending against it requires adaptive tracking systems that can follow these rapid changes, analysis of suspicious DNS patterns, such as unusually low time-to-live (TTL) settings, and close collaboration with DNS service providers to dismantle the underlying infrastructure.
Subdomain Hijacking
Subdomain hijacking occurs when a malicious actor gains control of a legitimate subdomain, often due to dangling DNS records, which are DNS entries that point to third-party services no longer in use. An attacker can register or claim the abandoned service, effectively taking over the subdomain. From there, they can host malicious content under the trusted domain name, redirect visitors to attacker-controlled sites, or launch phishing campaigns. It’s like finding an abandoned house with the keys still in the door. Regular DNS audits and continuous subdomain monitoring are key to preventing attackers from exploiting these vulnerable pathways.
Domain Squatting
Domain squatting is the practice of registering domain names that closely resemble those of well-known brands or different top-level domains. These domains often host malicious content and aim to attract users by exploiting typos or other misunderstandings. Malicious actors may use these domains to host phishing pages, distribute malware, or display misleading ads, putting user data and brand trust at risk. Others register them to resell at inflated prices.
Protocol Abuse
Protocol abuse in DNS occurs when malicious actors misuse legitimate DNS features or behaviors. By manipulating standard functions, such as query types, record fields, or packet sizes, they can enable data exfiltration, covert C2 activities, or traffic amplification, often without triggering security alerts. Common examples include using DNS tunneling to smuggle data out of a network or exploiting EDNS0, an extension to the DNS protocol that allows larger packets, to significantly amplify responses in DDoS attacks.
Pseudo-Random Subdomain Attack
A pseudo-random subdomain attack targets DNS infrastructure by flooding it with queries for unique, non-existent subdomains under a legitimate parent domain. Because each subdomain is different, the DNS server can’t use cached results and must perform a full lookup for every request. This spike in queries consumes processing power, memory, and bandwidth, disrupting the server’s ability to resolve legitimate requests, similar to a denial-of-service scenario.
NXDOMAIN Attacks
An NXDOMAIN attack floods a DNS server with queries for non-existent domain names, forcing it to repeatedly process requests that will always return an NXDOMAIN response. The constant barrage consumes CPU, memory, and bandwidth, degrading performance and reducing the server’s ability to answer legitimate queries. In severe cases, DNS services may become unavailable. This technique is used to disrupt services by displacing legitimate traffic with synthetic queries.
Cryptojacking
While cryptojacking itself is not a DNS attack, there is a connection. Cryptojacking is the unauthorized use of a device’s computing resources to mine cryptocurrency. Malicious actors often embed mining scripts within websites, inject them into compromised applications, or exploit misconfigurations to run them in cloud environments. In some cases, attackers will use DNS-based tactics like DNS hijacking to redirect users to sites hosting cryptojacking scripts. The stealthy nature of the attack means victims often remain unaware of the resource drain until systems slow noticeably or overheat.
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