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Four steps for denying DDoS attacks

How should banks and financial institutions deal with increasing numbers of large-scale denial of service attacks?

By Avi Rembaum and Daniel Wiley.

Financial institutions have been battling waves of large distributed denial of service (DDoS) attacks since early 2012. Many of these attacks have been the work of a group calling itself the Qassam Cyber Fighters (QCF), who until recently posted weekly updates on Pastebin about their reasons behind their attacks, and summarising Operation Ababil, their DDoS campaign.

Other hacktivist groups have launched their own DDoS attacks and targeted financial services institutions with focused attacks on web forms and content. There have also been reports of nation-state organized cyber assaults on banks and government agencies, along with complex, multi-vector efforts that have combined DDoS attacks with online account tampering and fraud.

These incidents against all sizes of banks have shown that there are many kinds of DDoS attacks, including traditional SYN and DNS floods, as well as DNS amplification, application layer and content targeted methods. Denial of service (DoS) activities that have targeted SSL encrypted webpage resources and content are an additional challenge. In some instances, the adversaries have moved to a blended form of attack that incorporates harder-to-stop application layer methods alongside ‘cheap’, high-volume attacks that can be filtered and blocked through simpler means.

To cope with this level of malicious activity, CIOs, CISOs, and their teams need to have a plan in place, and consider a set of defensive tools that combine on-premise technologies and cloud-based scrubbing services. They should also begin to explore and ultimately implement intelligence gathering and distribution methodologies that help lead to a comprehensive DoS mitigation strategy.

Here are four steps to help in devising that strategy:

Have a scrubbing service or ‘cleaning provider’ to handle large volumetric attacks
The volumes associated with DDoS activity have reached a level where 80 Gbps of DDoS traffic is a normal event. There are even reports of attacks in the range of 300 Gbps. Few, if any organizations can maintain sufficient bandwidth to cope with attacks of this size. When faced with DDoS incidents this large, the first thing an organization needs to consider is the option to route their Internet traffic through a dedicated cloud-based scrubbing provider that can remove malicious packets from the stream. These providers are the first line of defence/defense for large volumetric attacks, as they have the necessary tools and bandwidth to clean network traffic so that DDoS packets are stopped in the cloud and regular business as usual traffic is allowed.

Use a dedicated DDoS mitigation appliance to isolate, and remediate attacks
The complexity of DoS attacks and the tendency to combine volumetric and application methods require a combination of mitigation methods. The most effective way to cope with the application and ‘low and slow’ elements of these multi-vector attacks is to use an on-premise dedicated appliance. Firewalls and intrusion prevention systems are critical to the mitigation effort, and DDoS security devices provide an additional layer of defence through specialised technologies that identify and block advanced DoS activity in real-time. Administrators can also configure their on-premise solutions to communicate with cloud scrubbing service providers to enable automated route away during attack.

Tuning firewalls to handle large connection rates
The firewall will also be an important piece of networking equipment during DDoS attacks. Administrators should adjust their firewall settings in order to recognise and handle volumetric and application-layer attacks. Depending on the capabilities of the firewall, protections can also be activated to block DDoS packets and improve firewall performance while under attack.

Develop a strategy to protect applications from DDoS attacks
As well as using security solutions, administrators should also consider tuning their web servers, and modifying their load balancing and content delivery strategies to ensure the best possible uptime. This should also include safeguards against multiple login attempts. Machine-led, automated activities can also be blocked by including web pages with offer details, such as opportunities for interest rate reduction or information on new products, so that users much click on ‘accept’ or ‘no thanks’ buttons in order to continue deeper into website content. Content analysis can also help – simple steps such as ensuring there are no large PDF files hosted on high-value servers can make a difference.

The above methods are crucial to any DDoS mitigation strategy.

Organizations must also reach out to service providers and ISPs and work with them to identify novel mitigation techniques. After all, DDoS attacks use the same Internet routes as bank customers, and ISPs carry both forms of traffic.

Intelligence matters
Of increasing importance is the need to investigate and implement intelligence gathering and distribution strategies, both within company networks and across other companies operating in financial services.

Getting more information about who the attacking agent is, the motivations behind the attack, and methods used, helps administrators anticipate and proactively architect around those attacks. Attack profile information can range from the protocols used in the attack (SYN, DNS, HTTP), the sources of attack packets, the command and control networks, and the times of day during which attacks began and ended. While valuable in mitigating attacks, there is no easy way to communicate this data, and regulatory hurdles make it even more difficult to share attack information.

Right now, information-sharing consists of friends talking to friends. Information sharing needs to evolve into an automated system where multiple organizations can log in to a solution and see correlated and raw log data that provide clues about current and older attacks. Such systems could also be used to share attack intelligence and distribute protections. An industry information sharing capability would help elevate financial services companies’ abilities to cope with DDoS activity and bring the industry as a whole to a new level of preparedness.

The authors
Avi Rembaum is director of 3D consulting and Daniel Wiley is a senior security consultant at Check Point Software Technologies.

•Date: 23rd August 2013 • World •Type: Article • Topic: ISM

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