Malvertising: What it is and how to protect against it

The term malvertising refers to a type of advertising which is designed and sent out with the purpose of spreading malware. This is a basic definition, which however, has evolved considerably over time.

In order to understand the nature of this context, it is essential to remember that, even though an advertising banner may redirect you towards malware, it is unfortunately very difficult to distinguish between legitimate advertising and marketing messages posted online with fraudulent intent.

The situation is notoriously unclear. It can even happen that, following an extremely superficial analysis, some advertising is labelled as malvertising when it is in fact problem-free.

In order to explore this issue further, let us start with the characteristics of harmful advertising.

Malvertisement: what you should know

This kind of advertising can be identified by the fact that it re-directs users to sites which then infect their devices or start downloading unwanted programs. In order to counteract such issues, it is essential to install an up-to-date antivirus (users who don’t do this are particularly susceptible to malvertising).

On the subject of harmful or unwanted software, let us bear in mind that such programs can behave in a variety of ways.  If you are dealing with malware, remember that it can sometimes lead to a keylogger being installed on the device.

At that point, the user’s privacy is under serious threat. Keyloggers are able to steal personal login details for all user accounts. Also worthy of mention is malvertising which involves Trojan banking (false antivirus apps).

Malvertising: can it happen to important sites too?

Those who are unfamiliar with the world of the internet, often tend to think that important sites are immune to problems connected to malvertising. This is not true at all, as illustrated by cases such as Teslacrypt in the Netherlands, which infected visitors to some of the most prestigious websites, such as the official BBC and MSN sites.

How to protect against malvertising

It is only natural therefore, to wonder which are the right strategies to protect against malvertisements. As previously mentioned, the use of an antivirus is very important but not necessarily sufficient. To be sure of success, it is also a good idea to install an adblocker.  In this case users must be aware that any information constituting a possible source of financial gain must be removed from sites visited. It is also essential to update your operating system regularly.

Malvertising mechanisms exploit holes in old versions of Java and Flash, as well as in operating systems, as mentioned above.  Another useful piece of advice is to link donations to users’ favourite sites or registration for premium subscriptions to adblockers.

For many years now, cutting-edge editorial groups, such as the one behind the British Guardian newspaper, have provided users with the option to register for a voluntary subscription which allows them to access content without having to view advertising.

Conclusions

As mentioned above, malvertising does not necessarily involve sites which, when visited, cause the installation of malware. In some cases, in fact, it is ‘merely’ a question of online forms which are used for the traceability of cookies without the user’s consent.

Even if serious harm is not caused to devices and money is not stolen, this type of advertising is certainly not considered desirable. Users wishing to report it can lobby the advertising network who, in certain cases, have the power to suspend it.

Translated by Joanne Beckwith