Full Report
Since surfacing in 2019, Cl0p has extorted hundreds of millions of dollars from sectors ranging from healthcare and finance to manufacturing and education. Cl0p is known for its novel zero-day attacks and aggressive extortion methods. It is one of the most resilient and damaging ransomware threats of all time.
Analysis Summary
# Threat Actor: Cl0p Ransomware / TA505
## Attribution & Identity
* **Primary Group:** Cl0p ransomware operation, considered the "flagship" and most profitable unit of the cybercriminal enterprise **TA505**.
* **Affiliation:** Believed to be a Russian-speaking group operating out of Russia or the Commonwealth of Independent States (CIS).
* **Aliases/Variations:** Clop, CLOP, Cl0p (preferred stylization uses '0' to bypass filters), CLOP^\_, Clop, C\|0p.
* **Origin:** Thought to have emerged in 2019, potentially evolving from CrypBoss (2015) and CryptoMix (2016) ransomware strains.
## Activity Summary
* Active since 2019, extorting over $500 million globally.
* Became the most active ransomware group in Q4 2024, outpacing Akira and RansomHub.
* Surpassed LockBit as the most prolific ransomware group in Q1 2025 based on publicly disclosed breaches.
* Inflicts significant damage through high-profile **supply chain attacks**.
* TA505's broader activities include initial access brokering (IAB), high-volume phishing/malspam distribution, financial fraud, and large-scale botnet operations.
## Tactics, Techniques & Procedures
* **Initial Access:** Utilizing zero-day vulnerabilities (especially in supply chain software) and phishing campaigns timed during targeted region working hours. Attacks against vulnerabilities often occur during off-hours or long holidays to minimize IT staff availability.
* **Lateral Movement:** Utilizes standard offensive tools such as **Mimikatz**, **PsExec**, and **Cobalt Strike**.
* **Evasion/Persistence:** Disables **Windows Defender** and **backup processes**. Employs code obfuscation to hide malicious intent.
* **Data Exfiltration:** Steals sensitive data using custom tools like the **Teleport exfiltration tool**.
* **Encryption:** If encryption is used, files are renamed with extensions like `clop`, `CIIp`, `C_L_O_P`, or similar variations. Ransom notes typically use `Cl0pReadMe.txt` or `README_README.txt`.
* **Extortion:** If encryption fails or negotiations stall, the group resorts to data leaks, DDoS attacks, or harassment of victims.
## Targeting
* **Sectors:** Not explicitly listed, but known for high-profile **supply chain attacks**.
* **Geography:** Global targeting is implied by financial success, though actors avoid attacking organizations within Russia and former Soviet states. Command-and-control and payment infrastructure traced to Russia and Eastern Europe.
* **Victims:** Thousands of organizations affected globally.
## Tools & Infrastructure
* **Malware Families Used:** Cl0p (flagship), previously associated with TA505 activities using Dridex and Locky.
* **Infrastructure:** C2 and payment infrastructure traced to Russia and Eastern Europe.
* **Programming Artifacts:** Code comments and communications contain Russian language elements. The malware is specifically coded *not* to execute on Russian-language systems.
## Implications
Cl0p represents a highly resilient, adaptable, and technically sophisticated threat due to its integration within the larger TA505 operation, which provides access to initial access brokering resources and varied cybercrime pipelines. Their willingness to exploit zero-day vulnerabilities rapidly positions them as a primary threat to organizational continuity and data security.
## Mitigations
* Stay vigilant and apply security patches quickly, with special emphasis on all **file-transfer solutions** and other **supply chain software**.
* Employ multi-layered security solutions capable of detecting and preventing data theft and encryption activities.