What Is Malware: Definition and Examples

Every day, organizations face an invisible enemy that can strike without warning. Malicious software has become one of the most pressing security concerns for businesses of all sizes. Understanding what malware is and how it operates is no longer just an IT concern. It’s a business imperative that affects everyone from the boardroom to the break room.

Today’s threat actors deploy sophisticated attacks that can bypass traditional security software and infiltrate even the most protected networks. The financial damage from malware attacks amounts to billions of dollars annually, but the true cost extends beyond monetary losses to include lost productivity, damaged reputation, and compromised customer trust. Cybercriminals operate on the dark web, selling stolen credentials on the black market and offering malware as a service to other attackers.

Understanding malicious code

Malware, short for malicious software, refers to any computer program designed to infiltrate, damage, or disable computers and computer systems. From Trojan horses that masquerade as legitimate programs to ransomware that holds your data hostage, malware comes in many forms. What they all share is malicious intent to cause harm to your business.

Modern malware can remain hidden for months, quietly collecting data or establishing backdoors for future exploitation. The dark web marketplace for stolen data and malware tools has turned cybercrime into a thriving underground economy. Attackers sell everything from credit card numbers to complete database dumps, and the profits fund increasingly sophisticated attacks. Understanding how these threat actors operate helps you build more effective defenses against their tactics.

How malicious software enters your systems

Malware doesn’t just appear out of nowhere. It needs an initial infection vector to gain access to your network. Understanding these entry points helps you build better defenses.

Email remains the primary attack method

Phishing emails remain the most common method for malware to spread. Attackers craft convincing messages that trick users into clicking on malicious links or downloading infected email attachments. Common tactics include:

• Impersonating trusted brands or colleagues to build false credibility
• Creating urgent scenarios that pressure recipients into quick action
• Embedding malicious links in seemingly legitimate documents
• Attaching infected files disguised as invoices, reports, or contracts
• Spoofing executive email addresses to request sensitive information

Our security team sees thousands of these attempts daily, and the level of sophistication continues to grow.

Social engineering tactics have become alarmingly effective. Threat actors research their targets on social media sites and craft personalized messages that seem legitimate. They might reference a recent project or use company-specific terminology to build credibility. One click on a seemingly harmless file can launch a full-scale infection.

Web browsing creates vulnerabilities

Drive-by downloads represent another major threat vector. Visiting a compromised website can trigger the download of malicious code onto your system. Exploit kits scan for vulnerabilities in your browser or plugins and attack those weak points automatically. Fake security warnings also trick users into installing malware themselves by claiming their computer is infected.

Physical devices pose unexpected risks

USB thumb drives and external drives might seem harmless, but they can carry malware from one system to another. Attackers sometimes leave infected drives in parking lots or common areas, hoping someone will plug them in out of curiosity. Once connected, the malware automatically executes and begins its work. This tactic, known as “baiting,” exploits human curiosity and has proven surprisingly effective even in security-conscious organizations.

Remote Desktop Protocol (RDP) connections provide another entry point that attackers actively exploit. Weak passwords or unpatched systems make RDP a favorite target for automated attacks. SMB scanning tools enable attackers to identify vulnerable systems across the internet, probing for weaknesses that can be exploited. The shift to remote work has expanded this attack surface dramatically, as employees connect from home networks with varying levels of security protection.

The many faces of malware

Malware comes in multiple forms, each with distinct characteristics and attack methodologies:

• Viruses that attach to legitimate programs and spread through user actions
• Worms that self-replicate across networks without human intervention
• Trojan horses that disguise themselves as legitimate software
• Ransomware that encrypts files and demands payment for decryption
• Spyware that secretly monitors and collects user information
• Fileless malware that operates in memory without leaving traditional traces

Understanding these different types of malware helps your security team select the right defensive tools for each threat.

Viruses & Worms

Computer viruses attach themselves to legitimate programs and replicate when those programs run. They spread through infected email attachments, compromised downloads, or shared files. Worms self-replicate across networks automatically, spreading from system to system without requiring human interaction. These self-propagating threats can infect thousands of machines within hours, making them particularly hazardous for organizations with extensive networks.

Ransomware

Ransomware has evolved into a major criminal enterprise, with demands often running into millions of dollars for large organizations. Criminals threaten to publish stolen data on dark web leak sites if payment isn’t made, adding extortion to encryption. The Federal Trade Commission warns against paying ransoms, as payment doesn’t guarantee data recovery and funds future attacks.

Spyware

Spyware secretly monitors user behavior and collects information without the user’s consent. It might track web browsing habits, record keyboard activity through keyloggers, or capture screenshots of sensitive work. Password-management tools and two-factor authentication provide some protection against credential theft. Fileless malware operates entirely in memory, utilizing legitimate system tools, making detection and removal particularly challenging for traditional antivirus software.

How malware attacks unfold

Modern malware attacks follow a predictable pattern that security teams can learn to recognize. The initial infection vector provides the first foothold, often through a phishing attack, infected email attachment, or unpatched vulnerability. Attackers then work to gain higher-level permissions through privilege escalation, exploiting system vulnerabilities, or stealing administrator credentials to expand their access across your network.

The most sophisticated malware establishes communication with command and control servers, often referred to as C2 servers. These C2 servers let attackers issue commands, download additional tools, and exfiltrate stolen data. Threat actors hide this communication through encrypted channels or disguise traffic as legitimate web browsing to avoid detection by your security team. The ultimate goal is often data exfiltration, where attackers steal customer records, financial data, or intellectual property.

Supply Chain Management

Supply chain attacks have become particularly concerning in recent years. Attackers compromise software vendors or service providers to reach their real targets, affecting multiple organizations simultaneously. Endpoint detection and response tools help catch lateral movement, but attackers constantly develop new evasion techniques. 

Our platform continuously monitors third-party risks across your entire vendor ecosystem, providing real-time visibility into potential compromises before they impact your organization. This proactive approach helps security teams identify vulnerable vendors and take action to prevent supply chain breaches.

Defending against modern threats

Protection requires a multi-layered approach that combines technology, processes, and people.

Technology provides the foundation

Security software forms your first line of defense. Modern solutions go beyond traditional antivirus signatures to use behavioral analysis and artificial intelligence. Essential technical defenses include:

• Behavioral analysis tools that watch for suspicious patterns
• Firewall checks that filter incoming traffic and block malicious IP addresses
• Web application firewalls that protect against application-layer attacks
• Regular security patches that close exploitable vulnerabilities
• Endpoint detection and response systems that monitor device activity
• Advanced threat protection using artificial intelligence to identify new threats

These tools work together to create multiple layers of protection. No single solution stops every threat, but combining multiple defenses significantly reduces your risk exposure.

Zero trust security and monitoring

Zero trust security assumes nothing is safe. Every user, device, and application must prove its identity before gaining access. This approach limits damage from breaches by preventing compromised systems from automatically accessing everything else.

Continuous monitoring of your attack surfaces helps identify compromises early. Watch for these warning signs:

• Unexpected system slowdowns or crashes
• Programs running in the task manager that you don’t recognize
• Unusual network activity or data transfers
• Disabled antivirus software or security settings
• New browser toolbars or extensions appearing without installation
• Files with changed extensions or unexpected encryption
• Increased CPU usage when the system should be idle
• Warning messages claiming your system is infected

Your security team needs visibility into Internet of Things devices, cloud apps, and remote work environments. Cloud security posture management and Kubernetes security posture management tools offer specialized monitoring capabilities. Singularity cloud security platforms offer comprehensive visibility across hybrid environments. Infrastructure as code scanning checks deployment templates for security issues before they are deployed to production.

Building organizational resilience

Technology alone can’t solve your malware problem. You need a comprehensive program that addresses people, processes, and technology.

Security awareness training educates users

Your employees are both your greatest vulnerability and your best defense. Regular training helps them recognize phishing emails, suspicious attachments, and social engineering attempts. Key behaviors to teach include:

• Verifying sender identities before clicking links or opening attachments
• Avoiding public WiFi for sensitive business activities
• Using strong, unique passwords with password-management tools
• Enabling two-factor authentication on all accounts
• Being skeptical of urgent requests for money or credentials
• Reporting suspicious phone calls claiming to be from IT support
• Never plugging unknown USB drives into company devices
• Keeping personal vigilance high when conducting online banking or web browsing

Simulated phishing attacks test employee awareness and identify areas needing improvement. Training shouldn’t be an annual checkbox exercise. Ongoing reinforcement through short, regular sessions keeps security top of mind. Share real-world examples of attacks targeting your industry to make the threat concrete and relevant.

Incident response and backup strategies

When malware strikes, an incident response plan provides a roadmap for containment, eradication, and recovery. The plan should define clear roles, establish communication procedures, and outline technical response steps. Frequent tabletop exercises test your plan and identify gaps before a real incident occurs. Regular backups are your insurance policy against ransomware and destructive malware. Keep backups offline or in isolated networks where malware can’t reach them, and test restoration procedures regularly to ensure they work when needed.

Monitoring your systems for unusual activity helps catch infections early. The task manager displays running processes, but sophisticated malware like SmokeLoader often remains hidden from view. Advanced monitoring tools utilize behavioral analysis to identify hidden threats and suspicious patterns that indicate potential compromise.

The role of managed security services

Many organizations lack resources to maintain comprehensive security programs in-house. Managed security services provide expert support and 24/7 monitoring. Vulnerability management continuously scans for weaknesses before attackers exploit them. Professional incident responders bring expertise that most organizations lack, containing breaches faster and helping restore normal operations.

SecurityScorecard’s MAX managed service combines continuous monitoring with expert response. Our team watches your environment around the clock, identifies threats as they emerge, and takes action to protect your organization.

Staying ahead of threats

Understanding current attack trends helps you prioritize defenses effectively. Our STRIKE Team tracks emerging threats, analyzes attack patterns, and shares intelligence with customers through regular updates. We monitor the dark web for stolen credentials and leaked data, analyze new malware samples, including variants such as SmokeLoader malware and Mac malware, and track the behavior of threat actors across various industries. The Federal Trade Commission and Cybersecurity Awareness Program offer valuable resources for organizations fighting malware.

Malware often aims to facilitate identity theft or financial fraud through various means. Monitoring for compromised credentials on the black market helps identify when your data has been stolen, allowing you to take protective action before criminals exploit the information. Organizations using our platform gain continuous visibility into their attack surfaces through security ratings showing where vulnerabilities exist across their digital footprint.

We monitor over 12 million companies globally, providing unmatched insight into supply chain risks. This includes monitoring for threats targeting remote work environments, cloud apps, Internet of Things devices, and online banking connections. 

Want to see how SecurityScorecard can strengthen your defenses against malware and other cyber threats? Request a demo to discover how our platform offers continuous visibility and monitoring across your entire attack surface, enabling you to stay ahead of evolving threats.