DNS Attacks

From domain name system attack tactics to large-scale DNS attacks, learn how to recognize, understand, and defend against each threat.

What is a DNS Attack?

A DNS attack is a type of cyber incident where adversaries exploit weaknesses in the system that translates website names into IP addresses. This system (the Domain Name System, or DNS) handles the background process that makes DNS attack internet navigation possible. It routes traffic when someone opens a webpage, checks their email, or connects to a service online.

DNS attacks are made possible by a range of known DNS vulnerabilities, including cache poisoning and misconfigured resolvers. Because DNS is involved in nearly every internet transaction, attacks against it can cause widespread problems. Some aim to block access to services; others try to redirect users to the wrong destination or intercept what’s being sent.

Although most people think of DNS in relation to websites, it’s also used inside corporate networks - for example, to help internal systems locate one another. If DNS breaks down or gets tampered with, the impact isn't just external—it hits internal systems too. This kind of failure can interrupt everything from websites to back-office tools. Reports show these attacks aren't rare. They hit many sectors, and when they do, the average damage runs close to $950,000 per incident.

The reasons behind DNS attacks differ. In many cases, it's about money—diverting users to fake login pages or using access to trigger ransomware campaigns. Others are more strategic, designed for espionage or to extract sensitive data over time. A third group focuses on disruption, using DNS to amplify denial-of-service campaigns or disable communication channels.

Types of DNS Attacks and How They Work

DNS remains one of the few core internet protocols still widely used in its original, unauthenticated form. That legacy setup, mixed with config mistakes and spotty validation, leaves it open to attack. Some threats focus on changing what DNS servers send back. Others use the protocol's lightweight, stateless nature to push extra traffic or sneak harmful data into regular queries. The result is a mix of different techniques, each hitting a separate part of how DNS operates in today's networks.

Attacks That Compromise DNS Integrity

These attacks interfere with how DNS resolves names. Attackers inject fake data or change records somewhere along the lookup path. That lets them redirect traffic or pretend to be a legitimate site. A lot of the time, users won't notice anything wrong, which is exactly what the attackers want.

Type	How	Steps & Outcome
DNS Spoofing (Cache Poisoning)	This technique involves forging DNS responses to corrupt the cache of a recursive resolver. “Spoofing” refers to the act of deception, while “poisoning” describes the resulting state of the cache. Pre-conditions: Target resolver must lack a valid cached entry or be forced to refresh it.	Steps: Attacker floods the resolver with forged DNS replies, racing the real one. Matching transaction ID and port is critical. Outcome: The resolver stores a fake IP address for the domain, redirecting all users until the cache expires or is flushed.
DNS Hijacking	Alters the resolution path by taking control of DNS records or configurations at various layers. Pre-conditions: Access to registrar accounts, routers, or DNS server configurations.	Steps: Attacker modifies DNS records (e.g., via stolen credentials) or reroutes queries using infrastructure-level compromise. Outcome: Traffic for affected domains is redirected to servers managed by the attacker, often persistently.
DNS Rebinding	A browser-level trick that lets external websites access private network resources by rotating DNS answers. Pre-conditions: User must visit a malicious site with JavaScript enabled.	Steps: The site serves content with a low-TTL DNS record; after expiry, the domain resolves to a local network IP. Outcome: Browser treats the internal device as part of the same origin, allowing interaction or compromise.
DNS Typo squatting	Relies on users mistyping a legitimate domain name and landing on a malicious lookalike. Pre-conditions: Attacker registers a domain that mimics a popular site (e.g., amaz0n.com).	Steps: Victims enter the mistyped address and are served malware, phishing pages, or fake login screens. Outcome: Users unknowingly hand over sensitive data, thinking they are on the correct site.

Attacks That Exhaust DNS Resources

These attacks rely on volume rather than deception. They flood DNS infrastructure with large numbers of queries or exploit protocol behaviors that consume system resources. The goal is to slow down or disrupt name resolution by overloading resolvers or authoritative servers.

Type	How	Steps & Outcome
DNS Amplification	A type of DDoS attack that magnifies traffic by abusing open resolvers to send large responses to small queries. Pre-conditions: Open resolvers accessible on the internet and a spoofable victim IP.	Steps: Attacker sends small queries with the victim’s IP as the source; resolvers send amplified responses to the victim. Outcome: The victim receives a flood of large DNS responses, overwhelming bandwidth and resources.
DNS Reflection	Similar to amplification, but focuses on bouncing queries off resolvers to obscure the attacker’s identity. Pre-conditions: Open resolvers accessible on the internet and a spoofable victim IP.	Steps: Spoofed queries are sent to resolvers, which respond to the victim with seemingly legitimate traffic. Outcome: The victim suffers a denial-of-service attack, but cannot easily trace the true source.
DNS Flood / NXDOMAIN / Subdomain Flood	Overwhelms DNS servers with valid-looking or invalid queries. Pre-conditions: Target must accept recursive or authoritative queries.	Steps: Mass queries are sent for existing, non-existent, or randomly generated subdomains. Outcome: Resources are drained as the server processes and caches these requests, delaying or dropping legitimate queries.
Phantom Domain Attack	Deliberately targets resolver performance using slow or non-responding authoritative servers. Pre-conditions: Attacker registers and controls unresponsive or slow-to-respond DNS servers.	Steps: Queries are sent to these domains, occupying resolver threads until they time out. Outcome: Resolver pools are exhausted, affecting the ability to handle other DNS queries.
DNS Domain Lock-up	A variation of DoS that keeps resolver connections open using malformed or junk replies. Pre-conditions: Misconfigured resolvers that support TCP or extended interactions.	Steps: Attackers send partial or malformed data to hold connections open indefinitely. Outcome: Resolvers become unavailable as they wait for the "completion" of connections that never finish.

Techniques That Use DNS for Stealth or Data Exfiltration

In these cases, DNS is not the target but the channel. Attackers take advantage of how DNS traffic is handled to smuggle data out of a network or maintain covert communication. Since DNS is often overlooked by security tools, it can be used to bypass detection.

Type	How	Operation & Outcomes
DNS Tunneling	Uses DNS queries and responses to encode non-DNS data for command-and-control or data exfiltration. Pre-conditions: Malware inside the network and an attacker-controlled authoritative server.	Data is encoded into subdomains and sent via DNS queries; attacker’s server decodes and may reply with commands. Outcome: Enables stealthy, bidirectional communication that bypasses conventional controls.
Fast-Flux DNS	Rotates DNS records at high speed to avoid detection and takedown. Pre-conditions: Access to a botnet or compromised proxy network.	Domains are rapidly associated with different IPs, each active for only seconds or minutes. Outcome: Infrastructure remains operational despite IP blacklisting or tracking attempts.
Domain Generation Algorithms (DGA)	Malware generates domain names algorithmically to locate attacker servers dynamically. Pre-conditions: Both malware and attacker use the same domain-generation algorithm.	Malware generates domains daily; attacker registers some to maintain contact or control. Outcome: Communication persists even if most domains are blocked or taken down.

How DNS Attacks Affect Businesses and Technical Operations

DNS is the entry point for almost every digital interaction: cloud apps, email delivery, payment systems, and partner integrations all rely on those invisible lookups. If they fail, operations stall. And if resolution is hijacked, users are steered straight into harm’s way.

Service Disruption

DNS outages or manipulation can bring business to a standstill. Websites disappear. APIs time out. Email stops flowing. Even services that stay “up” become unreliable - slow, error-prone, or unreachable. In cloud and hybrid environments, where systems are stitched together through DNS-dependent automation, the damage can cascade fast. Redirected MX records can expose sensitive emails. Compromised update paths can swap patches for malware. In some cases, even internal systems misfire when local DNS is corrupted.

Significant Business Losses

The financial hit can be enormous. On average, DNS attacks cost organizations nearly a million dollars per incident, with some industries (like finance) facing even higher losses. That number includes more than just lost sales: SLA penalties, overtime costs, forensic investigations, and emergency fixes all add up. But the reputational damage is harder to price. When users can’t reach services (or worse, are silently redirected to fake ones), trust erodes fast. Downtime also makes headlines and can make customers leave. Regulators could take notice. However, restoring brand confidence is likely the hardest part, as it can take significantly longer than restoring systems.

Famous DNS Attacks

In 2016, the Mirai botnet launched a massive DDoS attack on DNS provider Dyn, taking down Twitter, Netflix, PayPal, and dozens of others across North America and Europe. The attack peaked at over a terabit per second and showed how fragile the internet becomes when DNS infrastructure is overwhelmed. Dyn lost nearly one in ten of its customers in the aftermath.

Two years later, attackers hijacked DNS traffic for MyEtherWallet users by manipulating BGP routes and spoofing Amazon’s DNS. A lookalike login page, $150,000 in stolen Ethereum, and a reminder: DNS can be more than a weak link, becoming a direct path to theft.

Identifying DNS Attacks

Most symptoms of a DNS attack look like ordinary glitches: slower loading, intermittent errors, or strange redirects. But some patterns stand out. Spotting them early can be the difference between a minor disruption and a full-blown incident.

Things to Watch For

NXDOMAIN spikes: A sudden rise in responses for non-existent domains usually means random-subdomain floods or domain enumeration.
Inconsistent IP resolutions: When the same domain resolves to different IPs - or known IPs suddenly shift to unknown ones - it may be cache poisoning.
SSL/TLS certificate warnings: If trusted HTTPS sites trigger certificate alerts but the domain name stays the same, think redirection or spoofing.
Queries to odd or obscure TLDs: Long subdomains or rare top-level domains can point to DNS tunneling or DGA activity.
Latency and timeout changes: DNS resolution slows down or fails more often than usual? It could be resource exhaustion or tunneling traffic.

How to Surface These Issues

Monitoring DNS traffic isn't just about collecting logs - it's about knowing what matters. A few approaches can help:

Passive DNS analysis helps flag shifts from normal query behavior over time.
SIEM integration connects DNS logs with firewall, endpoint, and user data to spot cross-domain anomalies.
Threat-intel enrichment highlights known malicious domains in real time, especially useful against DGA-driven queries.
Flow-based anomaly scoring looks at traffic volume, timing, and destination to catch patterns that don’t fit.
DNSSEC validation failures often mean tampered records or man-in-the-middle attempts.
Tools like Zeek or dnstop expose query trends. Sandboxing suspicious domains lets you safely observe what they’re trying to do.

Preventing DNS Attacks: Best Practices and Strategies

Hardening & Integrity Controls

Start the hardening process with authenticity at the protocol level. DNS Security Extensions (DNSSEC) add cryptographic signatures to DNS responses, making it much harder for attackers to poison caches or spoof records. Apply registrar-level domain locks to block unauthorized changes, and restrict DNS zone transfers to prevent infrastructure mapping. Disable recursion on authoritative servers, and keep all DNS software patched to avoid known exploits.

Traffic Inspection & Filtering

Protective DNS services and DNS firewalls block access to malicious domains. This can be done in real time using threat intelligence feeds. Many rely on Response Policy Zones (RPZ) to override risky queries. When paired with Secure Access Service Edge (SASE) frameworks, this filtering happens at the network edge - enforcing policy no matter where users connect. Add response rate limiting (RRL) to your authoritative servers to reduce amplification risk from automated floods.

Exposure Management & Resilience

Architect for containment. Keep recursive and authoritative servers separated to limit cross-impact during incidents. Use anycast DNS or multi-provider resolvers for geographic and provider redundancy. Regularly monitor DNS traffic for anomalies - unexpected spikes, stale records, or even certificate mismatches can flag issues early. Store secure backups of zone files, and train IT and security staff on DNS abuse tactics so they can spot weaknesses before adversaries do.

Recovery and Response to DNS Attacks

Immediate Steps: Revert any unauthorized DNS records with your provider. Flush poisoned entries from local and recursive DNS caches. Isolate affected resolvers from production traffic. Request upstream resolvers to clear stale data. Lock your domain at the registrar, and publish a brief service update.
Role of Incident Response Teams: Assign a triage lead to manage containment, a communication lead to coordinate updates, and a forensic analyst to preserve logs and trace the breach path.
Restoring Services and Mitigating Damage: Check zone-file integrity before reloading. Fail over to backup authoritative servers if needed. Test DNS resolution externally to confirm recovery.
Learning and Adapting: Debrief to confirm root cause. Update detection rules and DNS firewall feeds to prevent recurrence.

How Bitdefender can help?

The Bitdefender GravityZone platform delivers integrated protection against DNS-based threats through a unified security architecture that spans endpoints, networks, cloud workloads, and user behavior. By layering traffic inspection, behavioral analysis, and DNS-aware policy enforcement, it helps organizations can preempt, detect, and contain DNS-related compromises. This centralized cybersecurity platform combines prevention, detection, response, and risk analytics to defend against evolving DNS tactics across hybrid environments.

Network Attack Defense: Monitors Network traffic in real time to identify connections to known malicious domains or IP addresses, block tunneling activity used for command-and-control, and enforce policy-based protections at the network layer.
Content Control and Web Protection: Enforces DNS-layer policies to block access to malicious domains, phishing sites, and unauthorized categories - applied directly through endpoint security profiles.
Advanced Threat Control (ATC): Continuously inspects process behavior for signs of DNS tunneling, dynamic payload retrieval, or DGA-based communication.
Extended Detection and Response (XDR): Correlates suspicious DNS activity with endpoint, identity, and cloud telemetry to uncover multi-stage intrusions and exfiltration attempts.
Threat Intelligence: Supplies real-time malicious domain indicators - including DGA patterns, fast-flux infrastructure, and spoofed nameserver data - used to update filtering and response logic.
Patch Management: Reduces DNS exposure by ensuring authoritative servers and DNS-handling applications are patched against known exploits.
Sandbox Analyzer: Executes DNS-triggered samples in isolated environments to reveal malicious payloads hidden behind spoofed domains or resolver abuse.
Integrity Monitoring: Watches for unexpected changes to DNS settings—like zone files or resolver configs—and flags any signs of tampering or long-term compromise.
Managed Detection and Response (MDR): Delivers around-the-clock monitoring and expert response to stop DNS-driven attacks as they happen and shorten the time they stay active.

Overview

Definition
How it Works
Impact
Detection
Prevention
Recovery

Security Solutions

Frequently Asked Questions

Which is the most common type of attack against DNS?

It is difficult to give a definitive answer, but DDoS attacks against DNS systems are generally considered among the most common. These typically involve high-volume tactics like floods, reflection, or amplification—designed to overload servers and take them down. At the same time, DNS hijacking and cache poisoning (also called spoofing) remain persistent threats. Both can quietly reroute users to malicious sites without raising alarms. The bottom line: attackers go after DNS because it's foundational, and when it breaks, other dependent systems also stop functioning.

What is a DNS zone transfer attack?

DNS zone transfers are supposed to be routine - just one server updating another with domain info. But when that mechanism is left exposed to the public, attackers can abuse it to download the full DNS record set. That means gaining insight into internal IPs, subdomains, and infrastructure layout. It’s not a direct attack like a DDoS, but more of a reconnaissance move - a way to gain unauthorized insight into internal systems and plan something bigger. The fix is locking down zone transfers so only trusted servers can make the request.

What is the difference between DNS amplification and DNS reflection attacks?

The two often go hand-in-hand, but they emphasize different parts of the same trick. In a reflection attack, a DNS server is an intermediary system used to relay traffic: it’s tricked into sending replies to an unsuspecting victim by spoofing the source address. Amplification makes this worse by inflating the size of the response - so a tiny request turns into a flood of data. Reflection acts as misdirection, while amplification increases the scale of the attack. When combined, they create some of the most disruptive DDoS tactics seen today.