Top 4 Most Dangerous Ransomware Groups of 2025 & How to Defend

• What's Happening: Ransomware groups are highly organized criminal businesses, primarily using a Ransomware as a Service (RaaS) model to lease malware to affiliates for a share of the profits.
• Who Are the Key Players: In 2025, the most dangerous ransomware gangs include Cl0p, Qilin, Akira, and RansomHub, who have filled the void left by disrupted groups like LockBit and ALPHV/BlackCat.
• How They Attack: Their main tactic is "double extortion" . They steal your sensitive data before encrypting your systems, then threaten to leak it publicly if you don't pay.
• How to Defend: The best defense is a proactive one, centered on immutable backups, phishing resistant multi factor authentication (MFA), and timely patching, as recommended by authorities like CISA’s StopRansomware initiative and the NIST Ransomware Framework.

How We Gather This Data: This report is based on threat intelligence from our incident response engagements, analysis of dark web leak sites, and public advisories from cybersecurity authorities including CISA, the FBI, and NIST. We also incorporate data from leading threat research firms like CrowdStrike, Palo Alto Networks, and Check Point to provide a comprehensive and verifiable analysis. All data is current as of the last updated date.

The New Era of Digital Extortion

If you're trying to understand how ransomware groups operate in 2025, you're in the right place. These aren't lone hackers anymore; they are organized, professional, and run like criminal enterprises.

Ransomware has evolved from a simple malware threat into a systemic risk capable of shutting down hospitals, halting national supply chains, and exposing the data of millions.

The threat is accelerating. The first quarter of 2025 saw a staggering 126% surge in reported ransomware incidents compared to the previous year, according to a report from Check Point.

This report breaks down the modern ransomware ecosystem. We'll cover the business model that fuels these gangs, profile the key players, detail their attack methods, and give you an actionable guide to building a resilient defense.

What Are Ransomware Groups?

A ransomware group is a team of cybercriminals that uses malware to encrypt your files and demand payment to restore access. But today, they are much more than that. They are structured criminal organizations focused on one thing: extortion.

Their primary tactic is a devastating one two punch. First, they use powerful encryption to make your systems and data completely unusable. Second, they steal a copy of your most sensitive data before the encryption and threaten to leak it on the dark web if you don't pay.

This is double extortion, and it puts victims in an impossible position: a simultaneous business shutdown and a public data breach crisis.

The Ransomware as a Service (RaaS) Ecosystem

The engine driving this criminal industry is the Ransomware as a Service (RaaS) model. It mirrors the legitimate Software as a Service (SaaS) world, allowing skilled developers to lease their malicious tools to other criminals, known as affiliates.

The RaaS ecosystem has two main roles:

• Operators (Developers): The core team that builds the ransomware, maintains the data leak sites, and manages the payment infrastructure. They provide the tools and support.
• Affiliates: The criminals who carry out the attacks. They are responsible for gaining access to networks and deploying the ransomware, taking on most of the operational risk.

RaaS Pricing Models 2025

RaaS pricing models are designed for accessibility and profit. The most common is a profit sharing model, where the affiliate keeps 70-80% of the ransom and the operator takes a 20-30% cut. Other models include monthly subscriptions sometimes as low as $40 or one time license fees.

Double and Triple Extortion: The Evolution of a Tactic

Initially, ransomware was simple: attackers encrypted files and demanded a ransom for the key. But as organizations got better at making backups, they could often recover without paying.

In response, the Maze ransomware group pioneered double extortion around 2019. This tactic adds a second layer of leverage:

1. Data Encryption: The original threat of operational disruption.
2. Data Exfiltration: The new threat of a public data breach if the ransom isn't paid.

Even if your business can restore from backups, you now face regulatory fines, reputational damage, and legal action from the data leak. Some groups have even escalated to

triple extortion, adding DDoS attacks or directly contacting a victim's customers and partners to maximize pressure.

Major Ransomware Groups and Campaigns

The ransomware landscape is constantly shifting, but several key players have defined the threat in 2025.

Cl0p: The King of Zero Days

• Cl0p's Tactics: Unlike typical RaaS groups, Cl0p operates a centralized model, specializing in the mass exploitation of zero day vulnerabilities in secure file transfer software like MOVEit and GoAnywhere. They often prioritize mass data exfiltration over encryption, demanding payment to prevent the data leak.
• Cl0p's Impact: The 2023 MOVEit campaign caused widespread breaches affecting hundreds of major organizations. In H1 2025, Cl0p was responsible for over a third of all reported ransomware attacks, solidifying its position as one of the most dangerous ransomware gangs.

Qilin: RaaS, Weaponized

• Qilin's Tactics: Qilin is a full service RaaS platform that enables its affiliates to launch highly customizable attacks. They cast a wide net, hitting sectors from healthcare to manufacturing.
• Qilin's Impact: In July 2025, Qilin was the most active group, accounting for 12% of all published attacks. Their high profile attack on Synnovis in the UK severely impacted London hospitals, demonstrating their capability to disrupt critical services.

Akira: The Experienced Operator

• Akira's Tactics: First appearing in 2023, Akira targets Windows, Linux, and ESXi systems, with a strategic focus on manufacturing and business services. Their attacks are deliberate and aimed at causing maximum disruption.
• Akira's Impact: In July 2025, Akira claimed responsibility for breaching a U.S. defense contractor, stealing sensitive corporate and personal information. This highlights their focus on high value targets with national security implications.

RansomHub: The New Boss

• RansomHub's Tactics: RansomHub quickly rose to prominence in 2024 by attracting former affiliates from disrupted groups like LockBit and ALPHV. They operate with strong discipline and a threatening but measured approach on their leak site.
• RansomHub's Impact: They ended 2024 as the top group with 736 victims. In a mini case study from early 2025, RansomHub attacked major manufacturer American Standard, demonstrating their continued focus on large enterprises.

A Note on Legacy Groups

While new groups dominate the headlines, it's important to remember the names that built this criminal industry. Groups like Conti, DarkSide/BlackMatter, and Hive pioneered many of the tactics used today. Though now defunct or rebranded, their playbooks and malware source code often resurface in new operations. For example, researchers have noted similarities between Conti's TTPs and the Black Basta group, and the leaked source code of the Babuk ransomware has been repurposed by other actors. This ensures their destructive legacy continues.

How Ransomware Attacks Unfold

Most ransomware attacks follow a predictable lifecycle, often mapped to the MITRE ATT&CK framework. Understanding these stages is key to stopping an attack early.

1. Initial Access (TA0001): Attackers get their first foothold. This is often through phishing emails, exploiting unpatched vulnerabilities in internet-facing systems like VPNs, or using stolen credentials purchased from access brokers.
2. Execution and Persistence (TA0002 & TA0003): Once inside, they execute code and establish persistence to survive reboots. They may create new accounts or schedule tasks to maintain their access.
3. Privilege Escalation and Lateral Movement (TA0004 & TA0008): Attackers don't stay put. They move through the network to find high-value assets, often using legitimate tools like PowerShell and PsExec to "live off the land" and evade detection.
4. Data Exfiltration (TA0010): Before encrypting, they steal your data. They often compress sensitive files and upload them to a cloud storage service they control, setting the stage for double extortion.
5. Impact (TA0040): Finally, they deploy the ransomware. The payload rapidly encrypts files across the network using strong algorithms like AES 256, a technique MITRE ATT&CK classifies as MITRE ATT&CK framework classifies as T1486: Data Encrypted for Impact. Ransom notes are left behind with payment instructions.

How to Protect Against Ransomware (Step by Step)

A strong defense is a layered defense. The following steps are based on expert guidance from the CISA Ransomware Guide and NIST frameworks.

1. Maintain Offline, Immutable Backups: This is your most critical defense. Follow the 3 2 1 rule: 3 copies of your data, on 2 different media types, with 1 copy stored offline or in immutable storage where it cannot be altered. Regularly test your backup restoration process to ensure it works when you need it most.
2. Implement Aggressive Patch Management: Keep all software, operating systems, and firmware updated. Prioritize patching vulnerabilities listed in CISA's Known Exploited Vulnerabilities (KEV) catalog, as these are actively being used in attacks.
3. Enforce Strong Access Controls & MFA: Require phishing resistant Multi Factor Authentication (MFA) for all remote access, administrator accounts, and critical systems. Enforce the principle of least privilege so users only have the access they absolutely need.
4. Segment Your Network: Divide your network into smaller, isolated zones. If your business is targeted and one segment is breached, segmentation can prevent the ransomware from spreading to your entire network.
5. Develop and Practice an Incident Response Plan: Don't wait for a crisis to make a plan. A documented and rehearsed plan ensures your team knows exactly what to do to contain the threat and recover quickly. Our incident response services can help you prepare.
6. Conduct Continuous Security Validation: You can't defend against threats you can't see. Regularly test your defenses to find and fix gaps before attackers do. Our penetration testing services can simulate a real world attack to validate your security posture.

FAQs

Q: What is a ransomware group?

A ransomware group is an organized team of cybercriminals that uses malware to encrypt a victim's data and demand payment. Most now use double extortion, stealing data before encrypting it and threatening to leak it online to force payment.

Q: How does RaaS (Ransomware as a Service) work?

RaaS is a criminal franchise model where developers lease ransomware tools to affiliates for a share of the profits, typically 20-30%. This model makes sophisticated attacks accessible to a wider range of criminals, fueling the rise in ransomware incidents.

Q: Who are the biggest ransomware groups now?

As of 2025, the most prominent groups are Qilin, Akira, Cl0p, and RansomHub. The landscape is highly dynamic, with new groups constantly emerging to replace those disrupted by law enforcement.

Q: What industries do ransomware groups target?

They target any industry that is likely to pay. The most heavily impacted sectors are manufacturing, healthcare, government, and professional services because downtime is extremely costly and disruptive for them.

Q: How can organizations protect themselves from ransomware?

A layered defense is crucial. The most effective measures are: maintaining secure, offline, and tested backups ; enforcing phishing resistant MFA on all critical accounts ; patching vulnerabilities promptly ; and having a well practiced incident response plan.

Q: What is double extortion in ransomware?

Double extortion is when attackers both encrypt your files and steal a copy of your data. They then demand payment for two things: the decryption key to restore your systems and a promise not to leak your stolen data publicly.

Conclusion

Ransomware gangs in 2025 are more sophisticated and business-like than ever. The RaaS model ensures a steady supply of attackers, and tactics like double extortion are designed to defeat traditional defenses. For the latest on attack volumes and targets, see our guide to ransomware trends.

The only effective strategy is active readiness. Building a resilient defense requires a commitment to the fundamentals: strong backups, aggressive patching, robust access controls, and continuous security validation.

Ready to Strengthen Your Defenses?

The threats of 2025 demand more than just awareness; they require readiness. If you're looking to validate your security posture, identify hidden risks, or build a resilient defense strategy, DeepStrike is here to help. Our team of practitioners provides clear, actionable guidance to protect your business.

Explore our penetration testing services for businesses to see how we can uncover vulnerabilities before attackers do. Drop us a line, we’re always ready to dive in.

About the Author

Mohammed Khalil is a Cybersecurity Architect at DeepStrike with over 15 years of experience in threat intelligence and offensive security operations. Holding certifications including CISSP, OSCP, and OSWE, he has led numerous red team engagements for Fortune 500 companies and is a regular contributor to industry publications on threat actor TTPs. His work involves dissecting complex attack chains and developing resilient defense strategies for clients in finance, healthcare, and critical infrastructure.