What Is Denial of Service
A Denial-of-Service (DoS) attack is a cyberattack that deliberately overloads a website, application, server, or network with traffic or requests so that normal users can’t access it.
Types of Denial-of-Service (DoS) Attacks
Across major security references, DoS/DDoS attacks are usually grouped into three main categories, Volumetric, Protocol/Network, Application-Layer attacks based on how they exhaust resources
- Volumetric (Volume-Based) Attacks
- Flood the target with huge amounts of traffic (data or packets) to consume bandwidth.
- Example: UDP floods, ICMP (ping) floods.
- Protocol / Network Attacks
- Abuse weaknesses in network protocols or device behavior to exhaust resources in firewalls, routers, or servers.
- Example: SYN floods, Ping of Death, Smurf attacks.
- Application-Layer Attacks
- Target specific apps (like HTTP/HTTPS web services or APIs) with requests that are cheap for the attacker but expensive for the server.
- Example: HTTP GET/POST floods, Slowloris-style attacks.
A “simple” DoS usually comes from one source, but the same categories apply when attacks are distributed (DDoS) from many machines.
How a DoS Attack Works
Most DoS attacks follow the same basic idea that, to, exhaust a limited resource so real users can’t be served.
High-level flow:
- Attacker chooses a target and resource to exhaust
- Bandwidth, CPU, memory, open connections, or application threads.
- Attack traffic is generated
- Using scripts, tools, or one compromised machine (for DoS) to send a large number of packets or requests, or specially crafted packets that trigger heavy processing.
- The target gets overloaded
- Network pipes get saturated (no room for real traffic).
- Servers run out of CPU/RAM or max out on concurrent connections.
- Applications get stuck handling slow or complex requests.
- Legitimate users are denied service
- Websites time out or fail to load.
- APIs and apps become very slow or unresponsive.
- In severe cases, systems crash or need to be rebooted.
- Attack continues until mitigated
- Defenses (filters, rate limits, upstream scrubbing) are applied,
- Capacity is scaled and traffic is cleaned, or
- The attacker simply stops.
Common DoS Attack Types / Techniques
Most of DoS/DDoS Attack types were seen in, UDP Flood, ICMP Flood, SYN Flood, HTTP Flood, Slowloris, Smurf Attacks
- UDP Flood
Attackers send large volumes of UDP packets to random ports. The server keeps checking and responding, wasting resources and bandwidth. - ICMP (Ping) Flood
Overwhelms a target with ICMP echo requests (pings), consuming network and CPU until normal traffic can’t get through. - SYN Flood
Exploits the TCP three-way handshake. The attacker sends many SYN requests but never completes the handshake, leaving the server with many “half-open” connections and no room for real clients. - HTTP Flood (Application-Layer Flood)
Looks like normal web requests (GET/POST), but at extremely high volume or in resource-heavy patterns, so the web server or application gets overwhelmed. - Slowloris / Slow HTTP Attacks
The attacker opens many connections and sends data very slowly, keeping them open for as long as possible. This ties up web server threads and prevents new users from connecting. eSecurity Planet+1 - Smurf and Ping of Death (Classic Protocol Attacks)
Use spoofed or malformed ICMP packets, or broadcast amplification, to overload a victim or even crash older systems. GlobalDots+1
Importance of Understanding DoS Attacks
For an organization, understanding DoS attacks is critical because for the reasons of, impact availability, and possile cheap and common for attackers, used as smokescreen, and can able to affect all sectors
- They directly impact availability
A successful DoS attack can take down websites, APIs, VPNs, or business-critical apps, leading to lost revenue, missed SLAs, and operational disruption. - They are cheap and common for attackers
DoS and DDoS tools, botnets, and “DDoS-for-hire” services make it easy for even low-skilled attackers to launch impactful attacks. - They can be used as a smokescreen
Attackers may use DoS to distract defenders while carrying out data theft or lateral movement elsewhere in the environment. - They affect all sectors
Telecom, gaming, finance, healthcare, government, SaaS, and critical infrastructure regularly appear in DDoS reports. - Regulators and customers care about uptime
Extended outages can trigger contractual penalties, compliance issues, and long-term reputation damage.
How Loginsoft Helps You
At Loginsoft, we help organizations strengthen resilience against DoS and other disruptive cyberattacks. Our Threat Intelligence, Vulnerability Research, and Security Engineering Services enable teams to detect abnormal traffic, identify exploit patterns, and harden infrastructure against overload attempts.
Loginsoft supports organizations by
- Monitoring for suspicious network activity
- Identifying vulnerabilities targeted during DoS attacks
- Integrating protective controls across infrastructure
- Providing intelligence on emerging attack methods
- Supporting service continuity and recovery
Our mission is to ensure systems stay available, reliable, and protected - even under high-pressure cyberattacks.
FAQs - Denial of Service (DoS) in Cybersecurity
Q1. What is a DoS attack
A DoS attack overwhelms a system or network with excessive traffic, making it unavailable to legitimate users.
Q2. How is a DoS attack different from a DDoS attack
A DoS uses a single source, while a DDoS uses multiple systems or devices to launch the attack simultaneously.
Q3. Do DoS attacks steal data
No. A DoS attack disrupts service availability but does not directly involve data theft.
Q4. How can organizations protect against DoS attacks
Firewalls, rate limiting, traffic filtering, monitoring, and DoS mitigation services help reduce risk.
Q5. How does Loginsoft help defend against DoS attacks
Loginsoft offers threat intelligence, network monitoring, security engineering, and guidance to detect and mitigate DoS-related risks.
