What is a DoS attack really?

Threats & Hacks

Ordinary people here in Finland have been confronted with yet another cybersecurity acronym lately, DoS. And this does not mean that retro-minded people are converting back to the pre-Windows operating system MS-DOS that we used in the eighties. Today DoS stands for Denial of Service.

This case started on New Year’s Eve when customers of the OP-Pohjola bank experienced problems withdrawing cash from ATMs and accessing the on-line bank. The problems have now continued with varying severity for almost a week. What happens behind the scene is that someone is controlling a large number of computers. All these computers are instructed to bombard the target system with network traffic. This creates an overload situation that prevents ordinary customers from accessing the system. It’s like a massive cyber traffic jam. The involved computers are probably ordinary home computes infected with malware. Modern malware is versatile and can be used for varying purposes, like stealing your credit card number or participating in DoS-attacks like this.

But what does this mean for me, the ordinary computer user? First, you are not at risk even if a system you use is the victim of a DoS-attack. The attack cannot harm your computer even if you try to access the system during the attack. Your data in the target system is usually safe too. The attack prevents people from accessing the system but the attackers don’t get access to data in the system. So inability to use the system is really the only harm for you.

Well, that’s almost true. What if your computer is infected and participates in the attack? That would use your computer resources and slow down your Internet connection, not to speak about all the other dangers of having malware on your system. Keeping the device clean is a combination of common sense when surfing and opening attachments, and having a decent protection program installed. So you can participate in fighting DoS-attacks by caring for your own cyber security.

But why? Who’s behind attacks like this and what’s the motive? Kids having fun and criminals extorting companies for money are probably the most common motives right now. Sometimes DoS-victims also accuse their competitors for the attack. But cases like this does always raise interesting questions about how vulnerable our cyber society is. There has been a lot of talk about cyber war. Cyber espionage is already reality, but cyber war is still sci-fi. This kind of DoS-attack does however give us a glimpse of what future cyber war might look like. We haven’t really seen any nations trying to knock out another county’s networks. But when it happens, it will probably look like this in greater scale. Computer-based services will be unavailable and even radio, TV, electricity and other critical services could be affected.

So a short attack on a single bank is more like an annoyance for the customers. But a prolonged attack would already create sever problems, both for the target company and its customers. Not to talk about nation-wide attacks. Cyber war might be sci-fi today, but it is a future threat that need to be taken seriously.

 

Safe surfing,
Micke

 

Image by Andreas Kaltenbrunner.

 

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