This week Microsoft was the victim of a DDoS attack, which made online services such as mail service Outlook and video game Minecraft unavailable. A DDoS attack uses overwhelming traffic from multiple sources to make services and products unavailable to users.
While Microsoft have since implemented a fix for the problem, at the time of writing, service as normal has not resumed. Microsoft are a global organisation; on one hand this makes them a tempting target, but it also means that they have many sophisticated resources that are used to defend against and mitigate incidents such as this. Ironically, this time those systems backfired and exacerbated the issue.
DDoS attacks can be targeted to individual organisations, but they also target software and applications which can be used by many customers, allowing for organisations to unwittingly become collateral damage. To be able to defend against such attacks, organisations need to implement a multifaceted strategy combining technology, processes, and personnel training. Here are key measures that can help defend against DDoS attacks:
1. Implement Robust Network Architecture
Designing a resilient network infrastructure is crucial. This involves:
- Redundant Systems: Using multiple servers and data centres to distribute traffic loads ensures that if one server is targeted, others can take over.
- Load Balancers: Distributing incoming traffic across multiple servers to prevent any single server from being overwhelmed.
- Content Delivery Networks (CDNs): Leveraging CDNs can distribute traffic across multiple geographic locations, reducing the impact on the primary servers.
2. Intrusion Detection and Prevention Systems (IDPS)
Deploying IDPS helps monitor and analyse network traffic to detect unusual patterns indicative of a DDoS attack. These systems can:
- Identify Malicious Traffic: By recognizing attack signatures and anomalies.
- Automate Responses: Blocking or throttling suspicious traffic in real-time to mitigate the attack’s impact.
3. Rate Limiting and Traffic Shaping
Rate limiting restricts the number of requests a user can make to a server within a certain timeframe. Traffic shaping involves controlling the flow of data to ensure fair distribution of resources. Both techniques can:
- Reduce Load: Prevent excessive traffic from overloading servers.
- Protect Resources: Ensure critical services remain available to legitimate users.
4. Firewalls and Web Application Firewalls (WAFs)
Traditional firewalls can block unwanted traffic, while WAFs specifically protect web applications by filtering and monitoring HTTP traffic. These can:
- Block Malicious IPs: Stopping traffic from known malicious sources.
- Inspect Requests: Filtering out illegitimate requests that aim to exploit application vulnerabilities.
5. Anycast Routing
Anycast allows multiple servers to share the same IP address. During an attack, the network routes traffic to the nearest or least congested server, which:
- Distributes Load: Prevents any single server from being overwhelmed.
- Enhances Redundancy: Spreads the attack traffic across multiple locations.
6. Regular Security Audits and Penetration Testing
Conducting regular security assessments helps identify and address vulnerabilities. Penetration testing simulates DDoS attacks to evaluate the network’s resilience and:
- Expose Weaknesses: Allowing for proactive mitigation.
- Enhance Preparedness: Ensuring that the incident response plan is effective.
7. Incident Response Plan
Having a well-defined incident response plan ensures quick and efficient action during an attack. This should include:
- Clear Procedure: Identifying, mitigating, and recovering from an attack.
- Communication Protocols: Ensuring stakeholders are informed and coordinated.
8. Employee Training
Educating employees about DDoS attacks and their indicators helps in early detection and response. Training should cover:
- Recognising Symptoms: Identifying slow network performance or unavailability.
- Reporting Protocols: Ensuring swift escalation to the IT team.
By combining these strategies, organisations can create a robust defence against DDoS attacks, ensuring continued availability and reliability of their online services.
