Everything you need to know about malware, the virus that doesn't wait for winter to strike!

More than half of all businesses fell victim to a cyber attack in 2023. The culprit? Malicious software, commonly known as malware.

While the Hiscox 2023 report highlights this alarming reality (53% of businesses affected!), the exact nature of these threats and the means of protecting against them often remain obscure.

This article will tell you all you need to know about malware. On the programme: an explanation of what malware is, an overview of the worst digital parasites, practical advice on how to recognise the dangers, and a short guide to effective digital protection.

We're off!

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What is malware?

The term " malware " comes from the contraction of malicious software. But be careful: it's not just a computer virus that hangs around in your files doing nothing.

"Malware" is a generic term that encompasses a whole family of software developed for a single purpose: to do harm to your computer system, your data or your business.

Malware can :

• spy on your activities
• steal sensitive information
• destroy files;
• completely block a network by demanding a ransom.

It can be compared to a digital burglary: it breaks into your home, often without your knowledge, rummages around, steals what it wants... and sometimes even leaves a note ( ransomware).

The 6 most common types of malware

#1 Viruses

The computer virus is a bit like the old school of malware. It doesn't just infect a file: it seeks to replicate itself in order to infect other programs or machines. It often acts by stealth, waiting for the infected file or application to be launched.

Historically widespread in the 90s and 2000s, it is less common today, as other, more sophisticated forms have gradually replaced it. But it remains active, especially in contexts where systems are not regularly updated.

A virus can have several effects:

• slowing down the system ;
• file corruption ;
• application malfunction ;
• even complete destruction of data.

They are often used as an entry vector for other types of malware.

☝️ Note that some modern viruses no longer seek to destroy, but to exfiltrate data discreetly. Their authors focus on persistence rather than immediate chaos.

#2 The Trojan horse

📖 You know the story: the Greeks offer the Trojans a huge wooden horse. A poisoned gift, since inside it were hidden soldiers ready to invade the city.

In cybersecurity, it's exactly the same thing. The Trojan horse can take the form of a file, an application or even a completely innocuous email. An update, an invoice, an attachment with a reassuring title... Once executed, it opens a backdoor in your system.

This backdoor enables the attacker to gain remote access to your machine, often without you realising.

He can then observe, exfiltrate data, install other malware or take control of all or part of the system.

💡 This type of malware is particularly used in targeted attacks against businesses. Cybercriminals use it to prepare the ground for a more massive attack: data theft, encryption via ransomware, sabotage, etc. In short, with Trojans the packaging is pretty, but the inside is rarely festive.

#3 Ransomware

Ransomware is probably the most feared in the professional world.

Ransomware encrypts all the data on a computer or network, then demands a ransom to provide the decryption key. In plain English: your documents, databases and business tools become inaccessible... so you can no longer use any application and have to pay a ransom to get your tools working again. This is a form of cyber attack that affects a significant number of businesses.

⚠️ Some organisations prefer to pay to get back up and running quickly, but beware: there is no guarantee that cybercriminals will keep their promise.

LockBit, Conti and Ryuk are just a few of the known ransomware programs that have caused damage and have already paralysed hospitals, local authorities, industrial groups and SMEs. Another fact to know: a Sophos study estimates that the average cost of a ransomware attack is around €1 million. These costs include the ransom, estimated at €142,000 on average, but also the loss of business, reputation... and crisis management.

#4 Spyware

This malicious programme is spyware that operates with complete discretion. It surreptitiously spies on your every move: what you write on your keyboard, what appears on your screen, where you surf, etc.

It is therefore particularly dangerous if you handle sensitive or confidential information such as passwords or bank card numbers. It is often installed via a Trojan horse or a security hole.

Some versions are even capable of activating the host device's camera or microphone without your knowledge. You can easily imagine how dangerous it can be in a professional context.

Hidden by nature, spyware can provide strategic information to competitors over a long period of time, or lead to massive leaks of customer data.

#5 Adware

Adware (advertising software) is an extremely invasive advertising virus. Once you are infected, the worm spreads and floods you with adverts, often pop-ups.

Do you find it annoying, but harmless? Just remember that it can considerably slow down a system or redirect your searches to dubious sites.

This type of software is generally a gateway to the worst. And if it doesn't steal data as such, it can act as a gateway to more virulent malware.

☝️ Some adware also records behavioural data for resale to third parties. If you are infected by this type of malware, remain vigilant and close the security loophole as quickly as possible.

#6 The rootkit

The rootkit, also known as stealth malware, is the king of stealth. 🥷

This software hides in the deep layers of the system, making it very difficult to detect. It is also extremely dangerous, as it allows an attacker to take total control of a system, often by masking its own presence and that of other malware.

Its name comes from the fact that it gives remote root (administrator) access, undetected by conventional anti-virus software.

This type of attack is formidable for businesses, as it can allow the attacker to remain in a system for several weeks, or even months, without arousing suspicion, gathering information, creating vulnerabilities and preparing a larger-scale attack.

In other words, it's better to be able to detect any intrusion of malware into your machines quickly!

How do you recognise a malware infection?

To protect yourself as effectively as possible against malware, you need to be able to recognise the symptoms of infection quickly. Certain unusual behaviours should alert you immediately.

For example

• you notice unusual slowdowns on your computer, for no apparent reason ;
• programs, windows or applications launching by themselves; or
• strange error messages appear without explanation;
• a lot of intrusive advertising appears;
• your browser has changed search engine without you doing anything.

All these symptoms are signs that malicious software has compromised your IT security. In a professional environment, a simple piece of spyware can be enough to compromise sensitive data or leak strategic information. It is therefore essential to know how to remove the different types of malware.

How do you remove malware?

Once you've been able to identify with certainty the malware infecting your computer, here's how you can go about removing it.

Steps to follow

• First, disconnect the device from the Internet. By being offline, you prevent the hacker from controlling your computer in real time via remote access. This also prevents the risk of damaging your computer network.
  
  
• Restart in safe mode. Whether you're running Windows or another operating system, this is very easy to do.
  
  
• Scan with a reliable antivirus. The aim is for your antivirus to detect which files may have been damaged by the malicious attack.
  
  
• Delete or quarantine infected files. If a virus infects one file, the worst thing is for it to spread to others. So it's best to isolate or delete them to avoid this. If you have files that require particular vigilance, it's a good idea to have a backup in case you need to delete a version.
  
  
• Update your system and software. Sometimes your IT vulnerability can be explained simply by the use of obsolete tools. By keeping up to date, you reduce the risk of encountering other malware via the same vulnerability.
  
  
• Change your passwords. Once you've cleaned up, don't forget to change your access rights, and reinforce them if possible.

And if nothing works?

As a last resort, you should consider reformatting your device.

Or call in a cybersecurity professional. Removing malware is sometimes difficult and not without risk to do yourself.

For the rest, remember that prevention is the key to effective protection.

How can you protect yourself against malware?

1. Train your staff (especially non-techies)

The biggest vulnerability factor in your IT security is often the human aspect.

You can have the best malware detection tools, but if your team doesn't know how to use them, your protection will be useless.

In this respect, training is your best weapon and your first lever for action. Most hackers achieve their goals by exploiting a human vulnerability. For example, one well-known method is to send an email urging people to click on dubious links, or download an attachment.

💡 A culture of cybersecurity is essential to protect yourself! To develop collective vigilance, you need to ensure that everyone adopts the right reflexes. A simple idea to accompany this training is to incorporate simulation exercises (phishing, risky behaviour, etc.). These exercises help to transform theoretical awareness into lasting behaviour.

2. Implement a genuine ISSP

An Information System Security Policy (ISSP) is essential if you are to protect yourself effectively.

More than just a document, the ISSP is the backbone of your cybersecurity policy. A well-designed ISSP establishes the best practices you need to protect yourself:

• limiting access according to roles ;
• Impose strong passwords that are changed regularly;
• generalise multi-factor authentication;
• establish clear procedures for reacting in the event of an incident.

☝️ An IPSP is only useful if it is understood, applied and updated according to your needs. All these secure best practices must be communicated to your employees, including external service providers.

3. Choose the right tools

The toolbox of the good IT manager has expanded considerably in recent years.

New generation antivirus, intelligent firewalls, corporate VPN, etc. The challenge is to choose solutions that are :

• compatible with each other
• well configured
• adapted to your environment.

So, before you invest, ask yourself the right questions: What is your level of risk? Which workstations or servers are the most sensitive? Who administers what? Do your teams know how to interpret an alert?

Once you have the answers, you can find the right tools depending on the number of workstations you need to secure, how dangerous they are and how complex you can afford to use them.

💡 In all cases, favour tools capable of centralising alerts and generating clear reports. You'll save time... and peace of mind.

4. Keep it up to date. Always.

There's no secret about it: IT security is a constantly evolving sector, and cybercriminals are making progress too.

They have a well-honed routine: they scan for known vulnerabilities. And those that are not corrected become their favourite entry points. To counter this and keep your tools operational, you need to make sure they are up to date. You need to update everything regularly.

The operating system? Essential.

Business software? Also essential.

Browsers, extensions, plugins? Absolutely.

Network devices? Of course (routers, NAS, connected objects are all too often forgotten).

Every out-of-date version is a potential breach in your security. And in a world where the reaction time between the discovery of a flaw and its exploitation by a hacker can sometimes be counted in hours, responsiveness is your best ally.

💡 The best thing to do is to put in place an automated patch management policy, with alerts in the event of failure. Then test critical updates on a pilot machine before full-scale deployment.

5. Back up regularly

Last but not least: back-up.

Because even with all the precautions in the world, an incident can still happen. And when it does, you need to be able to restore your business... without panicking (or paying a ransom).

To avoid losing everything overnight, don't put off making back-ups. Hackers don't wait for your next meeting to attack.

Implement a backup strategy that is both local (hard disk, internal server) and in the cloud. Make sure that back-ups are automated, encrypted and tested regularly. Because a backup that doesn't work is like a disconnected alarm.

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Malware in a nutshell!

You now know more about malware, which refers to any form of malicious software. You know how dangerous it is: it can spy on and steal your data. They can even block your computer.

Whether in the form of viruses, Trojans, ransomware or anything else, the most important thing is to be able to spot them and remove them, but above all to prevent them from entering your computer system.

The key to this is good digital hygiene. Start building a culture of cybersecurity now. And what about tomorrow? With AI and connected objects ... malware could change shape. But the challenge remains the same: protecting machines and sensitive data.