How to counter DDoS attacks in Cloud Computing

Cloud services are becoming increasingly popular, both among the public and business enterprises. As more organizations are relying on cloud computing technology for their business operations, denial of service attacks (DoS), one of the most common forms of attack on the cloud, can prove extremely damaging.

A DDoS is an attack method used to deny access for legitimate users of an online service.  This service could be a bank or e-commerce website, a SaaS application, or any other type of network service. Some attacks even target VoIP infrastructure.  Basically, a DoS attack makes your network or machine unavailable to the intended users by flooding them with connection requests.

DDoS attacks vary in both sophistication and size.  An attacker can make a fake request look like random garbage on the network, or more troublesome, make the attack traffic look exactly like real web traffic.  In addition, if the attacker has enough computing resources at their disposal, they can direct enough traffic to overwhelm the target’s bandwidth.

The simplest types of attacks are Layer 3 and 4 attacks (IP and UDP/TCP in the OSI stack).  These simply flood the network and servers such that they can no longer process legitimate network traffic because the attacks have saturated the network connectivity of the target.  A more complex Layer 7 attack “simulates” a real user trying to use a web application by searching for content on the site or clicking the “add to cart” button.

Given that DDoS attacks are becoming more frequent, here are several tips on how you can prevent or fight back.

• Ensure there is an excess of bandwidth on the organization’s Internet connection – This is one of the easiest defenses against DDoS, but it can also be costly. The more bandwidth an organization has, the more attackers must do to block its connection.

• Determine vulnerabilities in your system – Scan your system to detect vulnerabilities. You can use vulnerability scanning tools to determine weaknesses that can be exploited to launch denial of service attacks. Make sure to implement security controls to fix the identified security issues.
• Use an intrusion detection system (IDS) – Several intrusion detection systems available today are equipped with the technology to protect systems for DDoS attacks by using connection verification methods and by preventing certain requests from reaching enterprise servers. IDS systems can also be configured to detect a threat and take corrective actions to prevent it.
• Maintain a backup Internet connection with a separate pool of IP addresses for critical users – This offers an alternate path if the primary circuit is overwhelmed with malicious requests.
• Configure firewall rules to filter out the malicious IP address – Configure firewall rules to monitor and filter out malicious traffic to prevent IP spoofing.
• Update patches – Make sure to regularly update security patches and software. Older versions of software are usually vulnerable to security attacks. Also, test for security updates and install them on routers, network hosts, and firewalls.

It’s your turn now. Did you ever face a DDoS attack? Please share your thoughts in the comments.

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