A malware attack is the unauthorized installation of malicious software designed to disrupt, damage, or gain illegal access to computer systems and networks. Attackers typically aim to steal sensitive personal or financial information, gain unauthorized access, or cause other forms of harm. Malware can target individuals, businesses, and governments, often leading to data breaches, financial losses, or operational downtime.
Malware attacks come in many forms, such as viruses, worms, trojans, ransomware, spyware, and more. Each type has its own method of infection and intended outcome, but the common goal is unauthorized control or exploitation of computer systems. As technology evolves, so do the techniques used by cybercriminals, making malware attacks more sophisticated and harder to detect.
Common types of malware attacks:
Common delivery methods:
In this article:
The following table summarizes the main types of malware attacks. Below we explore each attack in more detail.
| Malware Type | Primary Goal | How It Operates | Common Impact |
|---|---|---|---|
| Ransomware | Extort victims for payment | Encrypts files or locks systems and demands a ransom | Data loss, operational disruption, financial damage |
| Fileless Malware | Steal data or maintain access while avoiding detection | Executes in memory using legitimate system tools such as PowerShell or WMI | Credential theft, persistence, lateral movement |
| Spyware/Keyloggers | Collect sensitive information | Monitors user activity and records data such as credentials or financial information | Identity theft, fraud, account compromise |
| Trojans | Gain unauthorized access | Disguises itself as legitimate software and installs malicious functionality | Backdoors, remote access, malware delivery |
| Worms | Spread rapidly across networks | Self-replicates by exploiting vulnerabilities without user interaction | Network disruption, widespread infections |
| Botnets | Control compromised devices at scale | Connects infected devices to a command-and-control (C2) infrastructure | DDoS attacks, spam campaigns, credential attacks |
| Browser & DLL Hijacking | Manipulate trusted applications | Alters browser settings or replaces legitimate DLL files with malicious versions | Redirects, malware execution, credential theft |
| Living off the Land (LOTL) Attacks | Evade detection using trusted tools | Abuses built-in utilities such as PowerShell, PsExec, or Windows Script Host | Stealthy persistence, lateral movement, privilege abuse |
Ransomware is a type of malware that encrypts files or locks users out of their systems, then demands payment for restoration. Attackers usually request payment in cryptocurrency to make tracing more difficult. Victims are often pressured with threats of data deletion or public exposure if the ransom is not paid within a specified timeframe. Ransomware attacks can affect individuals, businesses, and critical infrastructure.
The rise of ransomware-as-a-service (RaaS) has lowered the barrier for launching these attacks. This model allows less skilled attackers to deploy ransomware using ready-made tools. Recent ransomware attacks have targeted healthcare, education, and government sectors, highlighting the need for backups, user training, and endpoint protection to reduce risk and impact.
Fileless malware does not rely on traditional files or software installations. Instead, it exploits legitimate system tools and processes, such as PowerShell, Windows Management Instrumentation (WMI), or macros within Office documents, to execute malicious code directly in memory. This technique makes fileless malware harder to detect because it leaves few traces on disk and can evade many traditional antivirus or endpoint security solutions.
Attackers often use fileless malware for credential theft, lateral movement within networks, or to establish persistence on compromised systems. The reliance on trusted system utilities means that even well-secured environments can be vulnerable if proper monitoring and restrictions are not in place. Organizations need behavioral detection, application control, and strict privilege management to counter this threat.
Spyware is malware designed to covertly monitor user activity and gather sensitive information, such as login credentials, browsing habits, or financial data. Keyloggers, a subtype of spyware, capture keystrokes to harvest passwords or other confidential information. These tools can operate silently for extended periods, transmitting stolen data to attackers without alerting the victim.
Spyware and keyloggers are often bundled with legitimate software or delivered through malicious email attachments and compromised websites. The information they collect is used for identity theft, financial fraud, or further attacks. Regular system scans, user education, and endpoint security tools help detect and remove these threats.
Trojans disguise themselves as legitimate software or files to trick users into installing them. Once executed, a trojan can open backdoors, download additional malware, or give attackers remote access to the infected system. Unlike viruses and worms, trojans do not self-replicate; they rely on social engineering or user error to spread.
Trojans are distributed through phishing emails, fake software updates, or malicious downloads. Attackers use trojans for data theft, espionage, or to maintain access within a network. Defenses include email filtering, application allowlisting, and user awareness training to recognize suspicious files and links.
Worms are self-replicating malware that spread across networks by exploiting vulnerabilities in operating systems or applications. Unlike viruses, worms do not require user interaction to propagate. Once inside a network, a worm can infect large numbers of devices, consume bandwidth and resources, and deliver payloads such as ransomware or spyware.
Worm outbreaks can cause widespread disruption and are often used to deliver other types of malware. Incidents like the WannaCry and NotPetya attacks highlight the importance of timely patching and network segmentation to prevent and contain worm propagation. Continuous vulnerability management helps reduce risk.
A botnet is a network of compromised devices, or "bots," controlled by a remote attacker. These devices, often infected with trojans or worms, are used to launch distributed denial-of-service (DDoS) attacks, spam campaigns, or credential stuffing. Botnets are managed through command-and-control (C2) servers, which enable attackers to coordinate malicious activities at scale.
Botnets pose risks due to their scale and versatility. Infected devices may include PCs, servers, IoT devices, and mobile phones. Regular device monitoring, strong authentication, and prompt patching reduce the risk of botnet infections and prevent devices from being recruited into malicious networks.
Browser hijacking malware modifies browser settings, redirects traffic, or injects ads without user consent. This can lead to credential theft, exposure to malware, or loss of privacy. DLL hijacking exploits the way Windows applications load dynamic link libraries (DLLs), allowing attackers to execute malicious code by replacing legitimate DLL files with altered versions.
Both browser and DLL hijacking techniques exploit trust in legitimate processes and applications. They are often used as initial access points for broader attacks or persistent threats. Regular software updates, browser hardening, and application control help prevent these forms of hijacking and limit their impact.
Living off the Land (LOTL) attacks involve the use of legitimate system tools and processes to carry out malicious actions. Attackers leverage utilities already present on the target system, such as PowerShell, PsExec, or Windows Script Host, to evade detection and execute commands. Because LOTL techniques use trusted components, they are difficult to detect with traditional security tools.
LOTL attacks are common in targeted intrusions and advanced persistent threats (APTs). Defending against them requires behavioral analysis, strict privilege management, and restricting the use of administrative tools. Regular monitoring and anomaly detection are critical for identifying and responding to LOTL activity before significant damage occurs.
Phishing emails remain one of the most effective malware delivery methods because they exploit human behavior rather than technical weaknesses. Attackers impersonate trusted organizations, coworkers, vendors, or service providers to convince recipients to open malicious attachments or click infected links.
These messages often create a sense of urgency, curiosity, or fear to encourage quick action without verification. Once a user interacts with the malicious content, malware such as ransomware, trojans, spyware, or credential stealers can be installed on the target device.
How to mitigate:
Compromised websites and malicious online content can infect devices without requiring users to intentionally download software. Drive-by download attacks exploit vulnerabilities in web browsers, browser extensions, plugins, or outdated applications to install malware automatically when a user visits a malicious or compromised site.
Cybercriminals frequently inject malicious code into legitimate websites or create fraudulent sites designed to distribute malware. Because these attacks often require little or no user interaction, they can be difficult to detect until systems are already compromised.
How to mitigate:
Unpatched software vulnerabilities provide attackers with direct opportunities to deliver malware and gain unauthorized access to systems. Vulnerabilities can exist in operating systems, business applications, web browsers, or third-party software components.
Attackers use automated scanning tools and exploit kits to identify systems running outdated software and then deploy malware through known security flaws. Organizations that delay patching are more likely to be targeted because publicly disclosed vulnerabilities often become part of attackers’ standard toolsets.
How to mitigate:
Removable storage devices, including USB drives, external hard drives, and memory cards, can introduce malware directly into corporate and personal environments. Attackers sometimes distribute infected devices intentionally, relying on curiosity or convenience to persuade users to connect them to a system.
Once connected, malware may execute automatically or exploit vulnerabilities in the host device to gain access. In environments with limited internet connectivity or strict network controls, removable media remains a common method for transferring malware between systems.
How to mitigate:
In 2025, Marks & Spencer experienced a major cyberattack that disrupted online ordering, contactless payments, and internal operations. The incident was part of a broader wave of attacks affecting major UK retailers.
This attack highlights the risk malware poses to retail and e-commerce environments. Retailers depend on connected systems for payments, inventory, logistics, customer accounts, and online sales. A successful malware attack can therefore disrupt both digital and physical business operations.
In 2025, Jaguar Land Rover suffered a cyberattack that disrupted manufacturing and retail operations. The company paused production at multiple sites while responding to the incident, affecting workers, suppliers, and vehicle delivery timelines.
This incident shows how malware attacks can affect manufacturing and supply chains. When production systems are disrupted, the impact can extend beyond data loss to halted assembly lines, delayed deliveries, supplier disruption, and significant financial damage.
In 2024, researchers identified AcidPour, a wiper malware variant linked to attacks against Ukrainian targets. Wiper malware is designed to destroy data or render devices unusable rather than steal information or demand payment.
This type of attack is especially destructive because recovery may be impossible if backups and recovery systems are also affected. Wiper malware is often associated with sabotage, cyberwarfare, or attacks intended to disrupt critical services rather than generate direct financial profit.
In 2024, attackers used credentials stolen by infostealer malware to access customer environments connected to Snowflake. The campaign affected major organizations and showed how stolen credentials from infected devices can later be used in large-scale data theft and extortion.
This incident demonstrates the growing role of infostealer malware in modern attacks. Infostealers collect usernames, passwords, browser cookies, session tokens, and other sensitive data from infected devices. Even if the original infection happens on a personal or contractor device, the stolen credentials can later be used to access corporate systems.
In February 2024, Change Healthcare suffered a major ransomware attack that disrupted healthcare payments, insurance claims, prescriptions, and billing operations across the United States. Because the company plays a major role in healthcare transaction processing, the impact spread across hospitals, pharmacies, insurers, and patients.
This attack shows the severe operational impact ransomware can have on critical sectors. Beyond encrypting systems or stealing data, ransomware can interrupt essential services, delay payments, create administrative backlogs, and affect patient care.
In June 2024, CDK Global, a major software provider for auto dealerships, experienced a cyberattack that disrupted dealership operations across North America. Many dealerships had to handle sales, repairs, financing, and customer records manually while core systems were unavailable.
This incident shows how malware attacks against service providers can cause widespread downstream disruption. When attackers compromise a central technology provider, the effects can spread quickly to many dependent businesses, even if those businesses were not individually targeted.
From 2023 onward, security agencies warned about Volt Typhoon activity targeting critical infrastructure. The attackers relied heavily on Living off the Land techniques, using legitimate system tools and compromised network devices to avoid detection. Their goal appeared to be long-term access and pre-positioning inside sensitive environments.
This campaign is an example of a stealth-focused malware-style intrusion where attackers avoid obvious malicious files whenever possible. Instead of relying on traditional malware alone, they used trusted administrative tools, stolen credentials, and normal network activity to blend in with legitimate operations.
In 2023, attackers compromised 3CX’s desktop application and distributed a trojanized version of legitimate software to customers. The attack used trusted software as the delivery mechanism, allowing malicious code to run on systems where users believed they were installing a normal business communications tool.
This incident is an example of a software supply chain malware attack. Instead of attacking each victim directly, the attackers abused a trusted vendor relationship to spread malware at scale. The campaign demonstrated how legitimate applications can become malware delivery channels when attackers compromise the software build or update process.
In 2023, international law enforcement disrupted QakBot, a long-running malware botnet that had infected more than 700,000 computers worldwide. QakBot was used to steal credentials, support financial fraud, and deliver additional malware, including ransomware.
This case shows the danger of botnet malware. Once a device is infected, it can become part of a larger criminal infrastructure controlled by attackers. Botnets like QakBot are especially dangerous because they can be reused for many purposes, including phishing, credential theft, malware distribution, and large-scale cybercrime operations.
In 2023, attackers exploited a zero-day vulnerability in MOVEit Transfer, a widely used file transfer platform. The campaign affected thousands of organizations and exposed data belonging to tens of millions of people. Although the incident was linked to an extortion group, the attack focused heavily on data theft rather than traditional file encryption.
This incident highlights how malware-related attacks are not limited to ransomware. Attackers increasingly use exploitation, data theft, and extortion together. By targeting a widely used business platform, they were able to compromise many organizations through a single software weakness.
Malware infections are not always obvious, but they often cause unusual changes in how a device, browser, account, or network behaves. Early warning signs should be investigated quickly. CISA defines malware as software used to gain unauthorized access, steal data, disrupt services, or damage IT networks. The FTC notes that malware can affect computers, tablets, phones, and other devices.
Potential signs of malware include:
Tips for early detection of malware attacks:
Attackers are increasingly using generative AI to create phishing messages that are more convincing, personalized, and difficult to detect. Instead of relying on generic templates with obvious spelling or grammar mistakes, cybercriminals can now generate polished emails that match a company’s tone, reference real people or events, and adapt messages for different targets. This makes phishing campaigns more scalable and more believable, especially when attackers combine AI-written messages with stolen personal data or information gathered from social media.
AI also improves social engineering by helping attackers respond quickly and naturally during conversations. For example, a malicious actor can use AI to draft replies, imitate an executive’s writing style, or create urgent-sounding requests that pressure employees into clicking links, opening attachments, or approving payments. As a result, organizations can no longer rely only on spotting poorly written messages; they need stronger identity verification, user training, email security, and multi-factor authentication.
AI-generated deepfake scams use synthetic voice, video, or images to impersonate trusted people, such as executives, coworkers, family members, or business partners. These scams are especially dangerous because they exploit trust and urgency. A victim may believe they are speaking to a real person on a phone call or video meeting when the attacker is actually using AI-generated media to request a money transfer, credential reset, or sensitive document.
Deepfake scams are becoming more accessible because attackers need less technical skill and less source material than before. A short audio clip or publicly available video may be enough to imitate someone’s voice or appearance. In business environments, this can support fraud, business email compromise, and malware delivery by making malicious requests appear legitimate. To reduce risk, organizations should verify sensitive requests through a separate trusted channel and avoid relying on voice or video alone as proof of identity.
AI-assisted malware development refers to the use of artificial intelligence to help attackers write, modify, debug, or improve malicious code. Generative AI tools can help less experienced attackers create scripts, automate repetitive tasks, or adapt existing malware to avoid detection. While AI does not automatically make every attacker highly skilled, it can lower the barrier to entry and speed up parts of the malware development process.
Attackers may also use AI to improve evasion techniques, generate malicious macros, analyze stolen data, or identify vulnerable systems more efficiently. This can make malware campaigns faster, more flexible, and harder for traditional security tools to detect. Defenders need to focus on behavior-based detection, secure coding practices, endpoint monitoring, and rapid patching rather than relying only on signature-based malware detection.
Identity-based malware attacks focus on stealing or abusing user credentials rather than immediately breaking into systems through technical exploits. Malware such as infostealers can collect passwords, session cookies, authentication tokens, browser data, and other identity-related information from infected devices. Once attackers obtain this information, they may be able to log in as legitimate users, bypass some security controls, and move through an organization with fewer signs of forced entry.
This trend is especially concerning because many modern attacks begin with valid credentials. Instead of triggering obvious malware alerts, attackers may appear to be normal users accessing email, cloud applications, or internal systems. Identity-based attacks often support ransomware, data theft, and lateral movement across networks. Strong MFA, conditional access policies, passwordless authentication, device health checks, and monitoring for unusual login behavior are important defenses against this type of malware-enabled intrusion.
Application control and allowlisting limit which programs, scripts, and binaries can run on a system. Organizations define approved applications and prevent others from executing. This reduces the risk of malware infections caused by unauthorized software or malicious scripts.
Allowlisting is effective against ransomware, trojans, and Living off the Land techniques that rely on scripting engines or administrative utilities. Organizations should restrict high-risk tools such as PowerShell, Windows Script Host, and macro execution where not required. Policies should also cover browser extensions, portable executables, and software running from temporary directories or user profile paths.
A Deny by Default approach blocks actions, applications, or network connections unless explicitly permitted. This reduces the attack surface by preventing unauthorized activity. Systems allow only approved behavior based on policy.
This model can be applied across endpoints, firewalls, identity systems, cloud platforms, and network segmentation policies. Organizations may block inbound connections, restrict administrative privileges, and deny execution from untrusted locations by default. Deny by Default controls help limit the impact of unknown malware, zero-day exploits, and lateral movement.
Many malware attacks exploit known vulnerabilities in operating systems, browsers, applications, and third-party software. Keeping systems patched closes security gaps commonly targeted through exploit kits, phishing attachments, or malicious websites.
Organizations should maintain a software inventory and prioritize patching internet-facing systems and actively exploited vulnerabilities. Automated patch management tools, vulnerability scanning, and regular update schedules reduce exposure. Unsupported or end-of-life software should be removed or isolated.
Multi-factor authentication (MFA) adds a verification step beyond a password, making it harder for attackers to access accounts using stolen credentials. Even if malware captures usernames and passwords, MFA can help prevent unauthorized logins.
Phishing-resistant MFA methods, such as hardware security keys or passkeys, provide stronger protection than SMS-based codes. Organizations should require MFA for remote access, email accounts, privileged users, VPNs, cloud applications, and administrative systems. MFA should be combined with conditional access policies and login monitoring.
Email is a primary delivery method for malware, including ransomware, trojans, and credential-stealing attachments. Organizations should use secure email gateways to scan attachments, block malicious links, filter spam, and detect phishing attempts before messages reach users.
Additional protections include disabling automatic macro execution, sandboxing attachments, and implementing SPF, DKIM, and DMARC to reduce email spoofing. User awareness training is also important because attackers rely on social engineering to bypass technical controls.
Network segmentation separates systems and devices into isolated groups to prevent malware from spreading across an environment. If one system becomes infected, segmentation can contain the attack and reduce its impact.
Organizations should restrict unnecessary communication between endpoints, servers, and administrative systems by using firewalls, VLANs, and access control policies. Limiting lateral movement is important for defending against ransomware and worms. Administrative privileges should be restricted to reduce the ability of attackers to move between systems.
Monitoring file execution helps organizations detect unauthorized applications, suspicious scripts, and unexpected software behavior. Malware often introduces new executables, modifies processes, or launches scripts from unusual locations.
Maintaining a software inventory helps identify outdated, unauthorized, or vulnerable applications. Endpoint detection and response (EDR) tools, centralized logging, and behavioral analytics improve visibility into malware activity. Regular reviews of installed software and execution patterns support faster incident response.
To stop malware attacks requires more than detecting threats after they execute — it means ensuring untrusted code never runs in the first place. Airlock Digital's application allowlisting delivers this through a Deny by Default model, where only trusted applications, scripts, and processes are permitted to execute and everything else is blocked. Built for real-world enterprise use, Airlock Digital pairs this foundational endpoint protection with practitioner-developed workflows and flexible tooling, so security teams can proactively block ransomware, zero-day threats, and unauthorized applications while keeping operations running.
Key capabilities of Airlock Digital application allowlisting:
Discover how Airlock Digital can help your organization stop malware before it runs - explore Airlock Digital application allowlisting.