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What is malware and how can you prevent it?

Read our guide to find out what malware is, why it exists, different types and how to prevent it to keep your organization safe.


Malware, short for malicious software, poses a significant risk to individuals, businesses, and even entire nations. With an innocent click on an infected email attachment, an erroneous download, or a visit to a risky website, the security of your entire network can be compromised.

Therefore, maintaining vigilance is not just recommended, but absolutely crucial in today’s digital landscape. 

But what exactly is malware and how can it be prevented? In this blog, we’ll cover all the information you need, including:

  • What is malware and what does it do?
  • Brief history of malware
  • How does malware work and spread?
  • Why do cybercriminals use malware?
  • How do cybercriminals use malware?
  • Why is malware a problem for organizations?
  • Different types of malware
  • A real-life example of malware
  • Which devices can be affected by malware?
  • How to know if you’ve been infected with malware
  • What to do if you get infected with malware
  • What steps can businesses take to prevent malware?
  • Final thoughts

What is malware and what does it do?

Malware refers to any software or program specifically designed to cause harm, exploit vulnerabilities, or gain unauthorized access to computer systems, networks, or devices. It encompasses a wide range of malicious programs, each with its own objectives and methods of operation, such as viruses, worms, trojans, and more.

This type of software can be distributed through various means, including infected email attachments, malicious websites, compromised software downloads, or even social engineering techniques.

Once it infiltrates a system, malware can carry out a range of harmful activities, like stealing sensitive information, hijacking computing resources, disrupting system functionality, or facilitating unauthorized access to systems or networks.

Brief history of malware

Malware has a rich history that begins with the self-replicating experiment known as the “Creeper” program in the 1970s. Alongside the proliferation of personal computers and the Internet, malware incidents became more widespread in the 1990s.

The early 2000s saw a surge in destructive worms and blended threats whereas the mid-2000s witnessed the emergence of financially motivated malware, like banking Trojans. Mobile malware targeting smartphones also began to emerge, and nation-state-sponsored attacks employing sophisticated malware made headlines.

Today, malware continues to evolve with techniques like polymorphism and fileless attacks taking place. Malware-as-a-Service (MaaS) can even be bought on the dark web, allowing those without technical skills to launch a campaign. 

How does malware work and spread?

Malware can work by exploiting vulnerabilities in computer systems, networks, or devices to carry out malicious activities. Malware can also use commonly used applications, APIs, functions and communication channels in order to blend in with ‘normal’ traffic and behavior.

Here is a general overview of how malware operates and spreads:

  1. Infection: malware enters systems through various vectors, including infected email attachments, malicious websites, compromised software downloads, or social engineering techniques.
  2. Execution: once inside, malware executes its payload, which can involve stealing sensitive information, encrypting files, gaining unauthorized access, initiating denial-of-service (DoS) attacks, or other malicious actions.
  3. Propagation: malware often seeks to propagate itself to other systems or devices. It may do so via:
    1. Self-replication: viruses and worms create copies of themselves to spread to other files, systems, or networks.
    2. Network-based propagation: malware exploits network connections to spread across local networks or the internet.
    3. Social engineering: malware tricks users into spreading it through deceptive tactics.
  4. Concealment: malware uses various techniques to hide its presence, including code encryption, hiding within system files or processes, rootkit functionality, or employing polymorphism.
  5. Persistence: malware establishes longevity within compromised systems by creating registry entries, modifying system files, or utilizing other methods.

Why do cybercriminals use malware?

Overall, malware is used with malicious intent. More specifically, it can be employed for a wide range of reasons, such as:

Financial gain

There’s a lot of money to be made with malware. Some common ways include:

  • Ransomware: cybercriminals encrypt victims’ files with ransomware and demand payment for the decryption key.
  • Banking trojans: targets online banking systems by stealing login credentials and financial information for unauthorized transactions or identity theft.
  • Cryptocurrency mining: infects systems with malware for profitable cryptocurrency generation using the device and resources of the victim and without incurring costs.

Data theft and espionage

Malware enables cybercriminals to steal sensitive information, trade secrets, or intellectual property. They can then sell the stolen data on the dark web and exploit it for personal gain or competitive advantage.

Botnets and Distributed Denial-of-Service (DDoS) attacks

Malware creates botnets (compromised computer networks controlled by criminals) which can be used to launch DDoS attacks. This overwhelms targeted websites or networks with excessive traffic and criminals demand payment to stop the attack.

Espionage and surveillance

State-sponsored actors and intelligence agencies use advanced malware to conduct espionage operations, targeting governments, organizations, or individuals.

How do cybercriminals use malware?

To distribute malware, cybercriminals utilize various techniques:

  • Phishing and social engineering: malicious emails disguised as legitimate communications that entice recipients to click on infected links or open infected attachments and lead to malware execution.
  • Malvertising: cybercriminals inject malicious code into legitimate online advertisements, redirecting users to malicious websites or triggering automatic downloads of malware.
  • Exploit kits: cybercriminals using exploit kits that automatically deliver malware to vulnerable systems after visiting compromised websites.
  • Watering hole attacks: cybercriminals compromise websites frequented by their intended targets, infecting the websites with malware. When the targets visit these sites, their systems become infected.
  • Drive-by downloads: cybercriminals leverage vulnerabilities in web browsers or plugins to silently download and install malware on victims’ devices when they visit compromised websites.

Why is malware a problem for organizations?

Malware is more than a pesky problem, it’s a pervasive and ever-evolving threat that demands constant vigilance. It causes potentially devastating consequences, such as:

  1. Data breaches and theft: malware can lead to data breaches resulting in the theft or compromise of sensitive information such as customer data, intellectual property, trade secrets, or financial records.
  2. Financial loss: malware attacks can result in direct financial losses for organizations. Ransomware attacks, for instance, can lead to significant ransom payments to regain access to encrypted files. Additionally, malware can facilitate unauthorized access to banking systems, leading to fraudulent transactions and financial theft.
  3. Operational disruption: malware can disrupt an organization’s operations, leading to downtime and productivity losses. Ransomware attacks, for example, can render critical systems or networks inaccessible, bringing business operations to a halt.
  4. Reputational damage: successful malware attacks can damage an organization’s reputation and erode trust among customers, partners, and stakeholders. The loss or mishandling of sensitive data can have long-lasting repercussions, leading to a loss of customers, tarnished brand image, and diminished market standing.
  5. Compliance and legal consequences: organizations often face legal and regulatory requirements to protect customer data and maintain adequate security measures. Failure to protect against malware and subsequent data breaches can result in non-compliance, leading to legal penalties, lawsuits, and regulatory sanctions.
  6. Intellectual property theft: malware can steal intellectual property, research and development data, or proprietary information. This can result in competitive disadvantages, loss of market share, and financial setbacks.
  7. Operational and supply chain risks: malware can infiltrate supply chains, introducing infected software or hardware components into an organization’s infrastructure, which can result in broader vulnerabilities.
  8. Rebuilding and recovery costs: recovering from a malware attack involves significant costs, such as Digital Forensics and Incident Response (DFIR) investigations, system repairs or replacements, data recovery, and strengthening security measures.

Different types of malware

From small-scale nuisances to sizable threats, malware appears in many sizes, formats, and types of severity. Here’s a brief overview:


These attach themselves to legitimate files or programs and replicate themselves when the infected file is executed. They can spread throughout a system or network, corrupting or deleting files, and potentially rendering the system inoperable.


These are self-contained programs that spread independently, often through network connections or email attachments. They exploit security vulnerabilities to propagate rapidly, consuming network resources and causing disruptions.


These disguise themselves as legitimate software to deceive users into installing or executing them. Once activated, they can provide unauthorized access to the attacker, steal sensitive information, or download additional malware onto the system.


This encrypts files on a victim’s system, rendering them inaccessible until a ransom is paid. It can spread through malicious email attachments, compromised websites, or exploit kits. 


This silently monitors user activities and collects information without the user’s consent. It can track keystrokes, capture passwords, record browsing habits, or gather personal data. 


This displays unwanted and intrusive advertisements on a user’s device. While not inherently malicious, it can negatively impact system performance, compromise user privacy, and potentially lead to further malware infections.


These are networks of infected computers, often controlled remotely by a bad actor. These compromised machines, known as “bots,” can be used for various purposes, such as launching DDoS attacks, sending spam emails, or conducting large-scale cybercrimes.


This is malicious software that tricks users into believing their devices are at risk by presenting false security alerts. It uses fear tactics to coerce victims into purchasing unnecessary or fake security products or services.

A real-life example of malware

One real-life example of malware is the WannaCry ransomware, which emerged in May 2017 and caused widespread disruption globally. WannaCry targeted computers running the Microsoft Windows operating system, exploiting a vulnerability in the Server Message Block (SMB) protocol.

Once a system was infected, the malware encrypted files and demanded a ransom in Bitcoin for their release. WannaCry quickly spread across networks, affecting thousands of organizations, including hospitals, businesses, and government institutions, causing significant financial losses and operational disruptions.

Which devices can be affected by malware?

Malware has the potential to affect a wide range of devices across various platforms, however, the level of vulnerability and types of attack may vary. The types of devices include:

  • Computers 
  • Mobile devices 
  • Internet of Things (IoT) devices, such as smart home devices 
  • Network equipment 
  • Point-of-Sale (POS) systems
  • Industrial Control Systems (ICS) 
  • Embedded systems like automotive systems 

How to know if you’ve been infected with malware

Detecting an infection can be challenging as malicious software often tries to operate covertly. However, there are several signs to look out for:

  • Sluggish performance: frequent crashes, slower start-up time. 
  • Unexpected pop-ups or ads: intrusive advertisements, redirects to unfamiliar webpages 
  • Unusual network activity: spike in internet data usage, unusual traffic 
  • Unusual system behavior: unexpected changes in your device’s settings 
  • High CPU or memory usage: unusual high memory usage during basic tasks 
  • Disabled security software: antivirus or firewall suddenly disabled or cannot be reactivated 
  • Unauthorized access or account activity: password changes, suspicious login attempts

In some cases, however, it’s not always this simple. With rootkits, for example, it’s recommended to mount the different drives whilst booted into another system, such a live-USB distribution and inspect it from there rather than from the infected system itself. This is because the malware might attempt to hide its presence at runtime.

It’s also good to know what a ‘healthy’ system looks like, such as what processes or services are expected to run and what they are for. This way you can spot unexpected processes easier.

What to do if you get infected with malware

Think you’ve already been infected? Follow these steps:

  1. Run a full system scan: use reputable antivirus or antimalware software to perform a thorough scan of your device.
  2. Disconnect from the internet: if you suspect malware, disconnect your device from the network to prevent further damage or unauthorized access.
  3. Remove suspicious software: uninstall any unfamiliar and suspicious programs or applications from your device through the control panel or settings menu.
  4. System recovery or wipe: to be approached on a case by case basis, removing suspicious software might not be as easy and so a full system recovery or wipe is advised.
  5. Update software: keep your operating system, applications, and security software up to date with the latest patches and updates, as they often include important security fixes.
  6. Change passwords: if you suspect your online accounts have been compromised, change your passwords immediately, using strong and unique passwords for each account.

What steps can businesses take to prevent malware?

Prevention is the most effective strategy for mitigating the impact of malware attacks and protecting the integrity of your security system. The optimal prevention strategy is a holistic and comprehensive approach that encompasses measures like:

  • Employee education and training: regularly train and educate employees about the risks of malware, phishing, and social engineering, including how to identify suspicious activity, avoid clicking unknown links, and report potential security incidents.
  • Strong password policies: enforce strong password policies that require complex passwords and the use of password managers, such as 1Password.
  • Regular software updates: keep all software, operating systems, applications, and plugins, up to date with the latest security patches.
  • Robust endpoint protection: deploy and maintain reputable antivirus and antimalware software on all endpoints. Configure regular scans and real-time protection to detect and block malware threats.
  • Secure network infrastructure: implement strong security measures, including firewalls, Intrusion Detection Systems (IDS) and Intrusion Prevention Systems (IPS), and secure Wi-Fi networks.
  • Secure email practices: deploy advanced security solutions to filter out spam, phishing attempts, and malicious attachments. Implement authentication protocols to prevent email spoofing and impersonation attacks.
  • Web filtering and content control: block access to malicious or untrusted websites known for hosting malware. Restrict the use of personal email accounts and limit access to potentially risky websites.
  • Regular data backups: implement a strategy to ensure critical business data is regularly and securely backed up. Test data restoration processes periodically.
  • Privilege management: commonly known as principle of least privilege, you should grant users only the necessary permissions to perform their tasks.
  • Incident response and business continuity plans: regularly test and develop incident response plans to ensure a swift yet effective recovery in the event of a malware infection.
  • Vendor and patch management: regularly assess and manage third-party vendors and their security practices. Implement a robust patch management process to promptly apply security updates for all software and systems used within the organization.
  • Regular security audits and penetration testing: search for vulnerabilities and weaknesses in your systems on a regular basis. Address any issues promptly and enhance security measures accordingly.

Final thoughts

The threat of malware is undebatable and alarming. As the name suggests, malicious software can wreak havoc on computer systems and networks, causing irreparable harm and disruption.

What makes malware particularly insidious is its pervasive nature and constant evolution. It adapts to new technologies and preys on the weakness of your cybersecurity stance.

Organizations can protect themselves from this threat by staying informed and implementing robust security measures. However, they can further reinforce their security posture by enlisting the help of professionals, like CovertSwarm.

CovertSwarm is a relentless and constant cybersecurity firm that helps organizations map out their attack surface. Our service works in line with your Security Operations Center (SOC) and helps protect against the threat of malware and bad actors.

To find out more about our Swarm, what we do and how we can help your business, get in touch today.