What is ransomware? Ransomware is a type of malicious software that locks or encrypts files on your system and demands a ransom to restore access. This type of cyberattack has grown increasingly sophisticated, targeting both individuals and organizations. In this blog, we’ll explore the different types of ransomware, explain how it works, and give you examples of some of the most notorious ransomware attacks in recent years.
What is Ransomware?
Ransomware is a type of malicious software (malware) that locks or encrypts files on a computer or network, making them inaccessible to the user. The attackers demand a ransom in exchange for unlocking the files or providing a decryption key. The ransom is often requested in cryptocurrency, such as Bitcoin, because it’s difficult to trace.
Ransomware attacks can lead to financial loss, data loss, and reputational damage, especially for businesses. The most alarming aspect of these attacks is the fact that they can happen to anyone, at any time, and the damage can be devastating.
Also read: What are the Common Cybersecurity Acronyms and Abbreviations?
How Does Ransomware Work?
Ransomware works by exploiting vulnerabilities in your system, encrypting your files, and locking you out of your own data until a ransom is paid. The process typically involves a series of steps that, once completed, result in the victim losing access to their files or systems. Understanding the specific stages and methods used by attackers can help you defend against these malicious programs.
1. Initial Infection (Infiltration)
The first step in a ransomware attack is infection, which can occur through multiple vectors. Ransomware is typically spread via phishing emails, malicious advertisements, or by exploiting security weaknesses in outdated software.
Common Methods of Infection:
- Phishing Emails: Attackers send emails with infected attachments or links. These emails may look legitimate and appear to come from trusted sources, such as a bank, co-workers, or even friends. Once the victim clicks on a malicious link or opens an attachment, the ransomware is installed.Example: A common phishing email might appear to be a legitimate invoice from a trusted company, with a link to view the invoice. Once clicked, the link downloads ransomware onto the victim’s computer.
- Malicious Websites or Ads: Known as malvertising, attackers use compromised websites or ads to deliver ransomware. Even by clicking on seemingly harmless ads or visiting untrustworthy sites, the ransomware can silently install on your system.
- Exploiting Software Vulnerabilities: Outdated or unpatched software is another entry point for ransomware. Attackers scan the internet for known security weaknesses in programs or operating systems and take advantage of these flaws to inject the malicious code.Example: The WannaCry ransomware attack in 2017 exploited a vulnerability in Microsoft Windows (called EternalBlue) to spread rapidly across unpatched systems.
2. Execution and Encryption of Files
Once the ransomware is installed, it begins to execute its main task: encrypting the files on the system. The ransomware uses advanced encryption algorithms, which can make the files completely unreadable without a decryption key.
- File Targeting: Ransomware typically targets the most common file types such as documents, photos, videos, and other important data. The attacker may focus on files that are valuable to the victim, like personal records or corporate intellectual property.
- Encryption Algorithms: Most ransomware employs powerful encryption methods, like AES (Advanced Encryption Standard) or RSA (Rivest–Shamir–Adleman) encryption. These are designed to ensure that decrypting the files without the key is nearly impossible.Example: CryptoLocker encrypts files using AES-256 encryption, which is nearly impossible to crack without the decryption key. Once files are encrypted, they cannot be accessed, and the victim is presented with a ransom demand.
3. Displaying the Ransom Note (Demanding Payment)
After the encryption is complete, the ransomware displays a ransom note on the victim’s screen. This note typically includes instructions on how to pay the ransom and a deadline for payment. The ransom is usually demanded in cryptocurrency, such as Bitcoin, because it is difficult to trace.
- Ransom Amount: The ransom demanded can vary greatly, from a few hundred dollars to tens of thousands, depending on the attacker’s target. The note often threatens to delete the files or leak sensitive data if the ransom is not paid within the specified time frame.
- Payment Instructions: The victim is usually instructed to buy cryptocurrency and send it to a Bitcoin wallet address provided in the ransom note. After payment, the attacker promises to provide the decryption key to restore the files.Example: The WannaCry ransomware displayed a ransom note that instructed victims to pay a fixed amount in Bitcoin, threatening to delete the encrypted files permanently if the ransom was not paid within 72 hours.
4. Double Extortion (Data Theft)
In recent years, some ransomware attacks have evolved into double extortion tactics, where attackers not only encrypt the victim’s files but also steal sensitive data. These attackers threaten to release or sell the stolen data unless the ransom is paid.
- Stolen Data: In addition to locking files, attackers may steal personal information, business data, or intellectual property, creating further leverage.Example: The Maze ransomware group was known for its double extortion tactics. After encrypting the files, the attackers would steal sensitive company data and threaten to release it publicly unless the ransom was paid.
5. Payment and Decryption (or Not)
Once the victim pays the ransom, the attacker is supposed to provide the decryption key to restore access to the files. However, there is no guarantee that the files will be decrypted, or that the attacker will honor the deal.
- Decryption Key: If the attacker follows through, the decryption key allows the victim to restore their files. However, the key might not always work, or the attacker may not send it at all after payment.
- No Guarantee: Paying the ransom does not guarantee that the attacker will return access to the files or that they won’t target the victim again.Example: Victims of WannaCry who paid the ransom found that the decryption tool provided by the attacker was often ineffective. Many businesses that paid the ransom were still unable to recover their data fully.
6. Aftermath of a Ransomware Attack
Even after paying the ransom (or in some cases, even after recovery), the victim’s system might still be compromised. The attackers could have installed additional malware or left backdoors open for further exploitation.
- Follow-Up Attacks: Attackers may leave a backdoor or additional malware behind, which could lead to further attacks or data theft.
- Reputation Damage: For businesses, a ransomware attack can lead to reputational damage, loss of customer trust, and legal consequences, especially if sensitive customer data is exposed.
Why Ransomware is So Effective
Ransomware is so effective because it exploits human behavior and system vulnerabilities. Here are a few reasons why ransomware attacks continue to be successful:
- Human Error: Many ransomware infections are caused by simple human mistakes, like opening an infected email attachment or clicking on a malicious link.
- Outdated Software: Many victims are vulnerable because they have not updated their systems with the latest security patches, leaving the door open for cybercriminals.
- Lack of Awareness: Users and organizations often lack proper awareness about the dangers of ransomware, making it easier for attackers to succeed.
Types of Ransomware
Ransomware attacks come in many shapes and sizes. The most common types of ransomware are categorized based on how they attack your system and the damage they cause. Below, we break down the different types of ransomware with clear explanations and examples.
1. Crypto Ransomware
Crypto ransomware is the most common and widely known type of ransomware. Its main goal is to encrypt files on your device, making them unreadable unless you pay the ransom.
1.1 How It Works:
- File Encryption: Crypto ransomware locks important files (documents, images, videos, etc.) with strong encryption.
- Ransom Demand: After encrypting the files, the ransomware demands a ransom, usually in cryptocurrency (e.g., Bitcoin) to provide a decryption key.
1.2 Examples:
- CryptoLocker: One of the first and most famous crypto ransomware strains. It encrypted files and demanded payment for decryption.
- WannaCry: A massive ransomware attack that exploited a vulnerability in Windows operating systems and infected hundreds of thousands of devices globally.
Key Features:
- Encrypts files, making them inaccessible.
- Ransom demands are usually high, and payments are often requested in cryptocurrency.
- No guarantee that files will be restored after payment.
2. Locker Ransomware
Unlike crypto ransomware, locker ransomware doesn’t encrypt your files—it locks you out of your entire system or device, preventing you from accessing anything.
2.1 How It Works:
- System Lock: The ransomware locks your computer or device and prevents you from using it. You may see a locked screen with a ransom note.
- Ransom Demand: You’re required to pay the ransom to unlock the system, but no files are encrypted.
2.2 Examples:
- Winlocker: This ransomware locks the victim’s system, making it unusable until the ransom is paid.
- Police Ransomware: This variant displays a fake message from law enforcement, claiming that illegal activity was detected on the system. It demands payment to unlock the device.
Key Features:
- Locks the system, preventing any usage until the ransom is paid.
- No encryption of files, only system access is blocked.
- Typically demands a smaller ransom compared to crypto ransomware.
3. Doxware (Leakware)
Doxware, also known as leakware, is a newer type of ransomware that not only locks or encrypts files but also threatens to expose or leak sensitive data unless the ransom is paid.
3.1 How It Works:
- Data Theft: In addition to locking files, doxware also steals sensitive information such as financial records, personal data, and confidential business information.
- Ransom Demand: The attacker threatens to release or sell this sensitive data unless the victim pays the ransom.
3.2 Examples:
- REvil: This ransomware group is notorious for stealing and threatening to release sensitive data if the ransom is not paid.
- Maze: Another variant that also uses the double extortion tactic—encrypting data and then threatening to release it publicly.
Key Features:
- Targets sensitive or private data in addition to locking or encrypting files.
- Threatens to publish or sell stolen data unless the ransom is paid.
- Often involves double extortion, where both encryption and data theft occur.
4. Scareware
Scareware is a type of ransomware designed to scare the victim into paying a ransom, often without any real malware being involved.
4.1 How It Works:
- Fake Alerts: Scareware displays fake alerts on your screen, often claiming that your system has been infected with malware or that illegal activity has been detected.
- Ransom Demand: The user is tricked into paying for unnecessary software or services to “fix” the issue, which is usually not real.
4.2 Examples:
- Fake Antivirus Software: The victim is told their computer is infected with viruses and that they need to pay to remove them, when in reality, the computer is not infected.
- FBI Ransomware: A variant that pretends to be a law enforcement agency, claiming the victim has committed a crime, and demands payment to avoid prosecution.
Key Features:
- No actual malware is involved—only fake warnings or pop-ups.
- Victims are tricked into paying for software or services that aren’t needed.
- Usually involves some form of social engineering to create urgency and fear.
5. Ransomware as a Service (RaaS)
Ransomware as a Service (RaaS) is a business model that allows anyone—regardless of their technical skills—to carry out ransomware attacks by renting ransomware tools.
5.1 How It Works:
- Ransomware Rentals: Cybercriminals who want to launch ransomware attacks can rent ransomware tools from other criminal organizations.
- Profit Sharing: The provider and the renter share the profits from the ransom payments.
5.2 Examples:
- Sodinokibi (REvil): This ransomware group offers its tools to other criminals in exchange for a portion of the ransom payments.
- NetWalker: Another RaaS operation, allowing low-level attackers to infect systems without needing technical expertise.
Key Features:
- Ransomware tools are provided to anyone willing to pay for them.
- The person who rents the tools shares the profits with the creator.
- Makes it easier for non-technical criminals to launch ransomware attacks.
Conclusion
Ransomware attacks continue to be one of the most dangerous and costly cybersecurity threats today. Understanding how ransomware works—from its initial infection to its final demands—is the first step toward protecting yourself and your organization. While no method is completely foolproof, combining proactive steps like regular backups, updating software, and awareness training can significantly reduce your risk of falling victim to a ransomware attack. The key is to stay vigilant and prepared—because, in the case of ransomware, prevention is the best cure.
For more information on how to protect against ransomware and the latest cybersecurity recommendations, visit the Cybersecurity & Infrastructure Security Agency (CISA). They provide valuable resources and updates on combating ransomware attacks.