The notion of a huge botnet targeting your business with a DDoS attack can send shivers down the backs of the most experienced security professionals. Botnets can harness vast size and power, as well as demonstrating a huge amount of sophistication.
DDoS attacks originating via botnets can be executed with precision and control, pulsed and sent in different ways and are virtually impossible to trace back to the original attacker. They are also growing exponentially in size as attackers take advantage of the range of connected devices incorporated in our Internet of Things. So what should security teams be watching out for, and what is the best defence?
Botnets have transformed the DDoS landscape. Once, attacks were the preserve of small, technical elites who had enough coding skills to launch a strike. Nowadays DDoS-for-hire botnets have significantly lowered the barriers to entry. A quick Google search and a PayPal account makes botnets readily available for just a few dozen dollars, with no coding experience necessary. Furthermore they are becoming increasingly popular – DDoS-for-hire botnets are now estimated to be behind as many as 40% of all network layer attacks, says Dave Larson, COO at Corero Network Security.
But while the majority of purchasers are likely to be low-level attackers, seeking to cause mischief and settle personal grievances, more powerful botnets-for-hire are also being utilised by state actors and organised criminals. Recently DDoS attacks have been getting bigger and bigger. Our Security Operations Centre recorded a dramatic (25%) increase in very large attacks of more than 10Gb per second among our customer base in the second half of last year. In terms of individual attacks, the strike on the BBC in January was one of the biggest ever reported; an enormous 600Gb per second.
While these attacks clearly cause significant damage, we believe that their primary purpose is often to demonstrate the attackers’ capabilities so that they can be sold as a service in the future. The gigantic attacks that make headlines aren’t cheap to rent and would probably cost upwards of $150,000 to engage. Accordingly these are only likely to be utilised by criminal or nation state attackers, who have access to a sophisticated infrastructure with money laundering capabilities.
There is really no limit to the potential size and scale of future botnet-driven DDoS attacks, particularly when they harness the full range of smart devices incorporated into our Internet of Things. By using amplification techniques on the millions of very high bandwidth density devices currently accessible, such as baby video monitors and security cameras, DDoS attacks are set to become even more colossal in scale.
Terabit -class attacks may be increasingly common and ‘breaking the Internet’ – or at least clogging it in certain regions – could soon become a reality. The bottom line is that attacks of this size can take virtually any company offline – a reality that anyone with an online presence must be prepared to defend against.
It isn’t just the giant attacks that organisations need to worry about. Before botnets are mobilised, hackers need to make sure that their techniques are going to work. This is usually done through the use of small, sub-saturating attacks which most IT teams wouldn’t even recognise as a DDoS attack. Due to their size – the majority are less than five minutes in duration and under 1Gbps – these shorter attacks typically evade detection by most legacy out-of-band DDoS mitigation tools, which are generally configured with detection thresholds that ignore this level of activity.
This allows hackers to perfect their methods under the radar, leaving security teams blindsided by subsequent attacks. If these techniques are then deployed at full scale with a botnet, the results can be devastating.
But that’s no reason for organisations to resign themselves to eventually getting attacked, despite the proliferation of vulnerable smart devices that can potentially comprise a botnet of near-unimaginable size. So what are the most effective methods of defence?
Legacy out-of-band scrubbing solutions which require human intervention to remove the attack will not be successful because they are slow to respond and they don’t recognise the full range of attacks. The alternative is to use an automatic, always-on, in-line DDoS mitigation system, which can monitor all traffic in real-time, negate the flood of attack traffic at the Internet edge, eliminate service outages and allow security personnel to focus on uncovering any subsequent malicious activity.
This type of protection comes in various forms – either on-premises, or purchased as a security service from an upstream provider. It’s technology like this which offers the best hope to organisations today against the biggest of botnets.
The author of this blog is Dave Larson, COO at Corero Network Security
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