> For the complete documentation index, see [llms.txt](https://learn.sitecove.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://learn.sitecove.com/how-to-guides/website-security-and-maintenance/malware-and-threat-protection/common-types-of-malware.md).

# Common Types of Malware

#### What is Malware?

Malware (malicious software) is any program or code designed to harm, exploit, or gain unauthorized access to a computer system or network. Cybercriminals use malware to **steal sensitive information, disrupt operations, and damage devices**. Understanding the different types of malware helps in implementing better security measures.

***

#### Ransomware

**What is Ransomware?**

Ransomware is a type of malware that **encrypts a victim’s files** and demands a ransom payment in exchange for a decryption key. Without the key, victims lose access to their files, making ransomware a major threat to businesses and individuals.

**How Ransomware Spreads**

* **Phishing Emails** – Malicious email attachments or links.
* **Exploit Kits** – Attacks on system vulnerabilities.
* **Malicious Websites** – Drive-by downloads from compromised websites.
* **Remote Desktop Protocol (RDP) Attacks** – Unauthorized access to remote systems.

**Examples of Ransomware**

* **WannaCry** – Global attack in 2017 affecting hospitals, businesses, and individuals.
* **Ryuk** – Targeted attacks on organizations demanding large ransom payments.
* **Locky** – Spread through email attachments disguised as invoices.

**How to Protect Against Ransomware**

* **Back up important files** regularly to an offline location.
* **Do not open suspicious email attachments or links**.
* **Keep software and operating systems updated** to patch vulnerabilities.
* **Use advanced endpoint protection** with behavior-based detection.
* **Disable Remote Desktop Protocol (RDP) if not needed**.

***

#### Spyware

**What is Spyware?**

Spyware is malware designed to **secretly monitor user activity** and collect personal information such as passwords, browsing history, and financial data. It operates in the background without the user’s knowledge.

**How Spyware Spreads**

* **Free Software Downloads** – Bundled with legitimate applications.
* **Malicious Websites** – Drive-by downloads that install spyware automatically.
* **Phishing Emails** – Fake links that trick users into downloading spyware.
* **Infected USB Devices** – Transferred through removable storage devices.

**Examples of Spyware**

* **Keyloggers** – Record keystrokes to capture passwords and personal data.
* **Trojan Spyware** – Disguises itself as a legitimate program while spying on users.
* **Pegasus** – Advanced spyware used to monitor government officials and activists.

**How to Protect Against Spyware**

* **Avoid downloading software from untrusted sources**.
* **Use a reputable anti-spyware or anti-malware tool**.
* **Enable browser security settings to block suspicious scripts**.
* **Regularly scan devices for spyware infections**.

***

#### Adware

**What is Adware?**

Adware is a type of malware that **displays unwanted advertisements** on a user’s device. While not always harmful, some adware can be intrusive, slow down performance, and redirect users to malicious sites.

**How Adware Spreads**

* **Bundled Software** – Hidden in free downloads and installed without user consent.
* **Malicious Ads (Malvertising)** – Fake online advertisements leading to malware downloads.
* **Browser Extensions** – Installed add-ons that inject ads into web pages.

**Examples of Adware**

* **Fireball** – Hijacks browsers and collects user data for ad revenue.
* **Gator** – Displays pop-up ads and tracks user browsing habits.
* **DollarRevenue** – Redirects users to unwanted advertising websites.

**How to Protect Against Adware**

* **Be cautious when downloading free software** and check for bundled applications.
* **Use ad blockers to prevent intrusive ads and tracking**.
* **Regularly clear browser cache and remove suspicious extensions**.
* **Scan devices with anti-adware tools to remove infections**.

***

#### Other Common Types of Malware

**Trojans**

* Disguised as legitimate software but performs malicious activities.
* Commonly used to install backdoors or steal data.

**Worms**

* Self-replicating malware that spreads across networks without user interaction.
* Causes widespread disruption and slows down systems.

**Rootkits**

* Grants attackers remote control over a system.
* Hard to detect as they operate deep within system files.

**Botnets**

* Networks of infected computers controlled remotely.
* Used for DDoS attacks, spam distribution, and data theft.

***

#### Summary of Malware Types and Prevention Methods

| Malware Type | Purpose                                                     | How It Spreads                                           | Prevention Methods                                          |
| ------------ | ----------------------------------------------------------- | -------------------------------------------------------- | ----------------------------------------------------------- |
| Ransomware   | Encrypts files and demands ransom                           | Phishing emails, exploit kits, malicious downloads       | Regular backups, patch vulnerabilities, disable RDP         |
| Spyware      | Monitors activity and steals data                           | Free software, phishing, infected websites               | Anti-spyware tools, safe browsing, security updates         |
| Adware       | Displays unwanted ads and collects data                     | Bundled software, browser hijackers, malicious ads       | Ad blockers, scan for malware, remove suspicious extensions |
| Trojans      | Disguised as legitimate software to perform malicious tasks | Infected downloads, fake software updates                | Use reputable software, enable antivirus protection         |
| Worms        | Self-replicates and spreads across networks                 | USB drives, email attachments, unpatched vulnerabilities | Regular software updates, disable autorun features          |
| Rootkits     | Hides deep in system files to gain control                  | Malicious downloads, backdoor exploits                   | Rootkit detection tools, avoid downloading unknown programs |
| Botnets      | Turns infected computers into a network for cybercrime      | Phishing, malware infections, compromised websites       | Use a firewall, monitor network activity, scan for malware  |

Understanding different types of malware and their behaviors is key to preventing infections and protecting devices and networks from cyber threats.