Tuesday, February 22, 2011
DDoS attacks: coming to a network near you
There has already been much fallout from the recent massive release of information by the WikiLeaks organisation--including attacks on WikiLeaks itself by those angered by its actions that aimed to disrupt and discredit the organisation. This saw WikiLeaks targeted by a variety of sustained distributed denial of service (DDoS) attacks that aim to make its web presence inaccessible.
Although these attacks were seen to be relatively modest in size and not very sophisticated, the publicity that they received has served to raise awareness of the dangers of such attacks, which can be costly and time-consuming to defend against. DDoS attacks occur when a hacker uses large-scale computing resources, often using botnets, to bombard an organisation's network with requests for information that overwhelm it and cause servers to crash. Many such attacks are launched against websites, causing them to be unavailable, which can lead to lost business and other costs of mitigating the attacks and restoring service.
DDoS attacks are actually extremely widespread. A recent survey commissioned by VeriSign found that 75% of respondents had experienced one or more attacks in the past 12 months. This is echoed in recent research published by Arbor Networks of 111 IP network operators worldwide, which showed that 69% of respondents had experienced at least one DDoS attack in the past year, and 25% had been hit by ten such attacks per month. According to Adversor, which offers services to protect against DDoS attacks, DDoS attacks now account for 4% of total internet traffic. Another provider of such services, Prolexic Technologies, estimates that there are 50,000 distinct DDoS attacks every week.
The research from Arbor Networks also shows that DDoS attacks are increasing in size, making them harder to defend against. It found that there has been a 102% increase in attack size over the past year, with attacks breaking the 100Gbps barrier for the first time. More attacks are also being seen against the application layer, which target the database server and cripple or corrupt the applications and underlying data needed to effectively run a business, according to Arbor's chief scientist, Craig Labovitz. Among respondents to its survey, Arbor states that 77% detected application layer attacks in 2010, leading to increased operational expenditures, customer churn and revenue loss owing to the outages that ensue.
Measures that are commonly taken to defend against DDoS attacks include the use of on-premise intrusion detection and prevention systems by organisations, or the overprovisioning of bandwidth to prevent the attack taking down the network. Others use service providers, such as their internet service provider (ISP) or third-party anti-DDoS specialists, which tend to be carrier-agnostic, so not limited to the services offered by a particular ISP. The first two options are time-consuming and costly to manage by organisations and they need the capacity to deal with the massive-scale, stealthy application-layer attacks that are being seen.
With attacks increasing in size and stealthier application-layer attacks becoming more common, some attacks are now so big that they really need to be mitigated in the cloud before the exploit can reach an organisation's network. ISPs and specialist third-party DDoS defence specialists monitor inbound traffic and when a potential DDoS attack is detected, the traffic is redirected to a scrubbing platform, based in the cloud. Here, the attack can be mitigated thus providing a clean pipe service--the service provider takes the bad traffic, cleans it and routes it back to the network in a manner that is transparent to the organisation.
Guarding against DDoS attacks is essential for many organisations and vital especially for those organisations with a large web presence, where an outage could cost them dearly in terms of lost business. DDoS attacks are becoming increasingly targeted and are no longer just affecting larger organisations. Rather, recent stories in the press have shown that organisations of all sizes are being attacked, ranging from small manufacturers of industry food processing equipment and machinery through to large gambling websites.
By subscribing to cloud-based DDoS mitigation services, organisations will benefit from a service that not only provides better protection against DDoS attacks than they could achieve by themselves, but can actually reduce the cost of doing so as the cost of hardware and maintenance for equipment required is spread across all subscribers to the service and organisations don't need to over-provision bandwidth as the traffic is directed away from their networks. For protecting vital websites, subscribing to such a service is akin to taking out insurance for ensuring that website assets are protected, and the organisation can protect itself from the cost and reputational damage that can follow from a successful DDoS attack that renders services unavailable