Clop Ransomware Group: Dark Web Data Leaks Case Study

What Is the Clop Ransomware Group?

The Clop ransomware group also written as Cl0p is one of the most consequential cyber-extortion actors of the last decade, not because of technical novelty, but because of how deliberately it reshaped the ransomware business model.

Clop represents a turning point where ransomware stopped being primarily an IT availability problem and became a data governance, legal, and reputational crisis. Organizations targeted by Clop are often fully operational when they discover they have been compromised. Systems are running, users are working, backups are intact yet the organization is already facing regulatory exposure, litigation risk, and public scrutiny.

This is why Clop continues to be referenced in government advisories, breach notifications, and board-level risk discussions long after many other ransomware brands faded.

Origins of Clop Ransomware Group and Its Connection to TA505

Clop is widely linked by threat intelligence vendors and government agencies to a long-running financially motivated cybercrime cluster tracked as TA505, sometimes overlapping with identifiers such as FIN11 or Graceful Spider depending on the vendor taxonomy.

TA505 is not a single gang in the traditional sense. It is better understood as an organized cybercriminal ecosystem that has operated since at least 2014, running multiple malware campaigns, ransomware programs, and monetization operations simultaneously. Over time, different “brands” have emerged from this ecosystem, with Clop becoming one of the most visible and damaging.

This matters because it explains Clop’s operational maturity:

• Access to experienced exploit developers

• Long-term infrastructure planning

• Legal and negotiation playbooks refined over years

• Ability to pause, retool, and re-emerge after law-enforcement pressure

Clop is not opportunistic crimeware. It behaves like a business unit inside a criminal enterprise, focused on return on investment rather than noise.

Early Clop:

Between roughly 2019 and 2021, Clop began experimenting with a different approach: steal the data first, then decide whether encryption is even necessary.

This evolution accelerated dramatically after Clop’s exploitation of enterprise file-transfer platforms. Instead of breaking into endpoints and moving laterally across networks, Clop realized it could target systems that already aggregate an organization’s most sensitive data.

The result was a fundamental change in how Clop applied pressure:

• Encryption became optional

• Downtime was no longer required

• Victims could not “restore” their way out of the incident

In many confirmed Clop cases, encryption never occurred at all. The extortion leverage came entirely from the threat of public data exposure.

Why Clop Avoids Encrypting Systems in Many Attacks

From a criminal economics perspective, avoiding encryption offers several advantages:

First, it reduces detection. File encryption is noisy. It triggers endpoint alerts, disrupts users, and forces rapid incident response. Silent data theft, especially from trusted enterprise systems, can go unnoticed for weeks.

Second, it scales better. Encryption attacks require per-victim execution. Supply-chain exploitation allows Clop to compromise hundreds or thousands of organizations in a single campaign.

Third, it maximizes pressure on leadership. Data exposure creates legal obligations, regulatory deadlines, and reputational fallout that IT teams cannot solve alone. This shifts negotiations from technical recovery to executive decision-making.

Finally, it neutralizes backups. Backups do nothing to stop leaked contracts, employee data, healthcare records, or intellectual property from appearing on the dark web.

For Clop, encryption is no longer the product. Exposure is.

Target Profile: Why Clop Focuses on High-Value Organizations

Clop consistently targets:

• Large enterprises

• Government agencies and contractors

• Healthcare providers

• Universities and research institutions

These organizations share several traits:

• Large volumes of sensitive data

• Regulatory oversight

• Brand and public trust considerations

• Complex third-party ecosystems

Small businesses are largely ignored not because they are secure, but because they lack leverage.

How Clop Ransomware Works?

Understanding how the clop ransomware operates requires abandoning the traditional mental model of ransomware as “malware that encrypts files.” The clop ransomware group does not rely on a single infection method or even a single technical playbook. Instead, it adapts its attack flow based on scale, data value, and exposure leverage.

At a high level, a clop ransomware attack follows a data-first lifecycle, not an encryption-first one.

Initial Access:

Clop differs from most ransomware groups by avoiding phishing and user-driven infection vectors, instead exploiting enterprise-facing systems especially managed file transfer platforms and data exchange software that handle large volumes of sensitive information. This approach allows Clop to steal data without deploying malware on endpoints, which is why traditional antivirus tools often fail, no infected devices are detected, and incidents are frequently discovered only after clop leaked data appears publicly.

Zero-Day and N-Day Exploitation at Scale

In multiple confirmed campaigns, clop ransomware has exploited newly disclosed or previously unknown vulnerabilities in widely used enterprise software, most notably through clop ransomware MOVEit, clop ransomware GoAnywhere, and reported clop ransomware Cleo activity. These operations follow a consistent pattern: an internet-facing service is compromised, authentication controls are bypassed or abused, and sensitive data is accessed and copied directly without encryption or modification.

Data Staging: Preparing for Exfiltration

Once access is achieved, Clop operators focus on data staging, not persistence.

This stage typically involves:

• Identifying directories containing sensitive business data

• Aggregating files into compressed archives

• Renaming or timestamp manipulation to blend into normal activity

• Temporary storage on the compromised system

Because many MFT and ERP systems are designed to move large files, these activities often appear legitimate in logs unless explicitly monitored.

Data Exfiltration Before Detection

In a clop ransomware attack, data exfiltration not encryption is the primary objective, and it is carried out using legitimate channels such as HTTPS, SFTP, and cloud APIs, often outside business hours and through the same pathways trusted by customers or partners. Because this activity rarely triggers endpoint-based detection, defenders must rely on network telemetry, detailed log analysis of MFT platforms, and outbound data monitoring to identify exposure. By the time exfiltration is detected, the damage is typically already done, even if no ransomware payload is ever deployed.

Extortion Without Encryption:

Once data exfiltration is complete, Clop shifts from technical intrusion to psychological and reputational pressure. Instead of deploying ransomware immediately, the group contacts the victim privately, provides proof of data theft, imposes a disclosure deadline, and threatens public exposure often without ever encrypting systems. This is why searches for a clop ransomware decryption tool frequently lead to dead ends: there may be nothing to decrypt, because Clop’s leverage lies in stolen data, not locked infrastructure.

Public Exposure via the Clop Dark Web Ecosystem

If negotiations stall, Clop escalates pressure through its clop dark web infrastructure by publicly listing victims, activating countdown timers to disclosure, releasing partial data as proof, and threatening full publication. Once listed, organizations face immediate media attention, regulatory scrutiny, and long-term exposure of clop leaked data, turning the incident into a full-scale business crisis rather than a contained IT issue.

Why Traditional Security Controls Struggle Against Clop

Many organizations affected by clop ransomware 2025-era activity had:

• Antivirus installed

• Backups available

• Patch management programs in place

Yet they were still compromised because:

• The attack bypassed endpoints

• The exploited system was “trusted”

• Detection focused on malware, not data movement

This is why Clop remains relevant and why people still ask: is clop ransomware still active   the answer is yes, because the model works.

Major Clop Ransomware Campaigns

The modern reputation of the Clop ransomware group was not built through hundreds of small intrusions. It was built through a small number of extremely large, high-impact supply-chain campaigns that reshaped how enterprises understand ransomware risk.

These campaigns share a defining characteristic: Clop did not attack end users   it attacked the software trusted by organizations to move their most sensitive data.

The MOVEit Transfer Campaign (2023):

The clop ransomware MOVEit campaign represents the most significant data-extortion operation publicly attributed to Clop. In mid-2023, the group exploited a previously unknown vulnerability in MOVEit Transfer, a widely deployed managed file transfer platform used by governments, enterprises, universities, and service providers. The flaw enabled attackers to bypass authentication, query backend databases, and exfiltrate stored files at scale without deploying traditional malware or encrypting systems, making it a case of mass exploitation rather than targeted intrusion.

Within weeks, hundreds of organizations worldwide confirmed data exposure across government, financial services, healthcare, education, and large enterprises, indirectly impacting millions of individuals. Many victims reported no encryption, no operational disruption, and discovered the breach only through third-party notification or public disclosure, cementing Clop’s evolution from a ransomware group into an industrial-scale data extortion operation.

GoAnywhere MFT Campaign:

Shortly before the MOVEit incident, Clop carried out another large-scale supply-chain attack through GoAnywhere MFT, demonstrating that its approach was deliberate and strategic rather than opportunistic. In the clop ransomware GoAnywhere campaign, attackers exploited a remote-code execution vulnerability in the product’s administrative interface, allowing them to execute commands, access file repositories, and exfiltrate sensitive business data without disrupting operations.

Affected organizations spanned manufacturing, healthcare, financial services, and logistics, with many systems remaining fully operational throughout the intrusion. In several cases, incident response efforts focused primarily on legal, regulatory, and compliance implications rather than system restoration, foreshadowing the broader data-extortion model that Clop would later amplify in the MOVEit campaign.

CLEO File Transfer Platforms:

The clop ransomware CLEO activity represents a more complex and less centrally documented case. Credible reports and victim disclosures suggest that Clop targeted certain CLEO file transfer products used for B2B data exchange across supply chains, retail, logistics, and large partner ecosystems. Unlike the MOVEit and GoAnywhere campaigns, public confirmation of scale remains limited, with attribution relying largely on victim statements, threat actor claims, and early-stage reporting rather than consolidated public investigations.

Why Supply-Chain Software Is CLOP’s Preferred Attack Surface

Across clop ransomware moveit, clop ransomware goanywhere, and clop ransomware cleo, a clear pattern emerges.

Clop prioritizes software that:

• Aggregates sensitive data

• Operates continuously

• Is exposed to the internet

• Is implicitly trusted by enterprises

From an attacker’s perspective, these systems:

• Remove the need for phishing

• Eliminate endpoint security controls

• Provide immediate access to regulated data

• Enable multi-victim compromise with a single exploit

This is economics, not opportunism.

Clop Dark Web Infrastructure & Leak Sites

When organizations hear that their data has appeared on the dark web, the common assumption is that it has been dumped randomly into criminal forums. With the Clop ransomware group, the reality is far more structured, deliberate, and psychologically engineered.

Clop does not simply leak data it orchestrates exposure. Its dark web infrastructure is intentionally designed to operate as an extortion platform, a credibility mechanism, a public pressure engine, and a reputation system for the attackers themselves. Every listing, countdown, and data release is part of a controlled escalation strategy.

Understanding this infrastructure is critical for executives, legal teams, and incident responders, because activity on the dark web often drives legal, regulatory, and reputational consequences faster than the technical breach itself.

Structure of Clop Leak Sites

Clop’s leak sites follow a consistent and deliberately engineered structure designed to support data extortion rather than random disclosure. Each victim is listed individually with the organization name, industry, status (such as negotiation, countdown, or published), and a defined disclosure deadline. For many organizations, appearing on this list is the first confirmation that a compromise has occurred.

A key feature of Clop’s infrastructure is the use of visible countdown timers, which create artificial urgency and force rapid escalation to executives, legal teams, and boards. These timers compress investigation and decision-making timelines, often shifting incidents from technical response to crisis management even while negotiations are ongoing.

To establish credibility, Clop publishes proof-of-breach artifacts such as internal screenshots, database records, financial data, or file samples. Once disclosure escalates, leak pages expand into structured file repositories showing directory paths, retention labels, and segmented downloads, making clop leaked data persistently accessible. This structure transforms a security incident into a reputational, legal, and regulatory event driven by public exposure rather than system disruption.

Types of Data Published by Clop

Analysis of Clop leak activity shows a consistent focus on high-impact data, not random files.

Commonly observed categories include:

• Employee personally identifiable information (PII)

• Financial records and invoices

• Legal contracts and NDAs

• Healthcare and insurance data

• Internal communications

• Intellectual property and proprietary documents

The value of this data lies not only in resale, but in how damaging its public exposure can be.

Clop Leaked Data Analysis

The defining characteristic of a Clop ransomware group incident is not system downtime it is the long-term exposure created by stolen data. Once information appears as clop leaked data, the impact extends far beyond the initial security incident and continues to evolve over time.

This section examines what is actually exposed in a clop data breach, why it is so damaging, and how organizations underestimate secondary risk.

Understanding the Nature of Clop Leaked Data

Unlike opportunistic cybercrime that indiscriminately dumps available information, Clop releases highly targeted and context-rich datasets. The group deliberately focuses on data that creates regulatory obligations, triggers contractual liability, damages trust with customers and partners, and retains value long after initial publication. This intentional selection is why clop leaked data is repeatedly cited in legal filings, breach notifications, and regulatory investigations, extending the impact well beyond the initial incident.

Industries Most Affected by Clop Leaks

Analysis of known Clop victim disclosures and dark web listings shows clear industry concentration.

Healthcare Organizations

Healthcare entities are disproportionately affected by Clop due to the volume and sensitivity of data they manage, including patient records, insurance information, billing data, and employee PII. A healthcare-related clop data breach often triggers mandatory regulatory disclosures, immediate scrutiny from authorities, increased class-action litigation risk, and long-term erosion of patient trust. Even limited exposure can carry severe operational and reputational consequences.

Universities and Research Institutions

Universities and research institutions are frequent Clop targets because of decentralized IT environments, high-volume data exchange, and close collaboration with government and industry partners. Clop leaked data in these cases commonly includes student records, research datasets, grant documentation, and intellectual property tied to ongoing projects, creating significant risk to funding, academic credibility, and institutional reputation.

Enterprises and Professional Services Firms

Large enterprises targeted by Clop often face exposure of HR databases, financial statements, legal contracts, M&A documentation, and internal communications. For professional services firms, the impact is magnified, as a single breach can affect multiple clients simultaneously, multiplying legal liability, regulatory scrutiny, and reputational damage across the organization’s customer base.

Data Sensitivity Classification: Why Clop Data Is So Dangerous

Clop leaks rarely involve low-value information. Instead, they frequently include regulated and strategic data.

Personally Identifiable Information (PII)

Clop leaks frequently expose high-value PII such as names, contact details, national identifiers, and employee or customer records. This type of data enables identity theft, targeted fraud, credential abuse, and creates long-term regulatory and monitoring obligations for affected organizations.

Financial and Contractual Data

Leaked datasets often include invoices, payment records, vendor agreements, pricing structures, and confidential financial reports. This information can be weaponized for fraud, competitive intelligence, and contractual or legal disputes, extending the impact beyond immediate breach response.

Intellectual Property and Sensitive Internal Data

In some incidents, Clop releases source code, product designs, research data, and internal strategy documents. Exposure of this material turns a security incident into a long-term competitive and strategic risk rather than a purely technical issue.

Who Is at Risk? Why CLOP Targets High-Value Organizations

One of the most common misconceptions about the Clop ransomware group is that it targets organizations indiscriminately. In reality, Clop is highly selective. Victim choice is driven by leverage, not vulnerability alone.

Understanding this targeting logic is critical for executives and security leaders, because it explains why well-resourced organizations continue to suffer major Clop incidents, while many smaller businesses are ignored entirely.

Is Clop Ransomware Still Active?

Yes - Clop ransomware remains active and dangerous, not because of frequent encryption attacks, but due to its long-lasting extortion model. Previously stolen data continues to resurface, pressure on victims often extends months after compromise, and Clop’s methods have influenced newer threat actors. Many enterprises also continue to rely on the same high-risk data platforms, making Clop’s activity persistent and episodic rather than constant background noise.

Why Clop Avoids Small Businesses

Clop operates on return-on-investment logic rather than volume. Small businesses are typically unattractive because they hold limited sensitive data, face minimal regulatory pressure, generate little media attention, and have low ransom-payment potential. As a result, most high-profile clop ransomware attacks involve organizations that are financially stable, operationally mature, and publicly visible.

The Clop Victim Profile: What Makes an Organization Attractive

Clop targets organizations with high data density, particularly those operating managed file transfer systems, enterprise platforms, data exchange gateways, and third-party integration hubs, where large volumes of sensitive information are centralized and easy to monetize through extortion. The more data aggregated, the greater the leverage.

The group also prioritizes victims with regulatory and legal exposure, including organizations subject to data protection laws, industry compliance requirements, and mandatory breach disclosure rules. These frameworks transform data theft into legal obligations, regulatory deadlines, and financial penalties, increasing pressure to negotiate.

Indicators of Compromise (IOCs) for Clop Ransomware

Key IOCs Indicating a Breach in CL0P MOVEit Campaign (CVE-2023-34362)

The definitive signs of a breach (successful compromise via the SQL injection vulnerability) are the presence of LEMURLOOT web shells on the MOVEit Transfer server. These files were uploaded by attackers post-exploitation to maintain access, steal data, and stage further actions.

Primary Breach IOCs (Web Shell Files – High Confidence of Compromise if Found):

• human2.aspx (most common, usually size 6249 bytes) – Multiple hash variants exist; any matching file in MOVEit directories signals breach.

  • Example hashes:

    • SHA-256: A1269294254E958E0E58FC0FE887EBBC4201D5C266557F09C3F37542BD6D53D7 (MD5: DDD95F1C76A1D50B997B2E64274F386A)

    • SHA-256: F0D85B65B9F6942C75271209138AB24A73DA29A06BC6CC4FAEDDCB825058C09D (MD5: 9F3C306DABC3F349B343251F4443412C)

    • SHA-256: CF23EA0D63B4C4C348865CEFD70C35727EA8C82BA86D56635E488D816E60EA45 (MD5: B69E23CD45C8AC71652737EF44E15A34)

    • (Many more variants in the list – all with size 6249 bytes and similar patterns)

• donotuse_human2.aspx (size 6249)

  • SHA-256: 348E435196DD795E1EC31169BD111C7EC964E5A6AB525A562B17F10DE0AB031D

• h2.aspx (size 6428)

  • SHA-256: D477EC94E522B8D741F46B2C00291DA05C72D21C359244CCB1C211C12B635899

• upload.txt or UNAVAILABLE (sometimes used as decoy names, size 6249 or 6223)

  • Example: SHA-256: 387CEE566AEDBAFA8C114ED1C6B98D8B9B65E9F178CF2F6AE2F5AC441082747A

Supporting IOCs (Indicate Ongoing Exfiltration or Post-Breach Activity):

• Connections to malicious domains (e.g., connectzoomdownload.com, zoom.voyage, qweastradoc.com, guerdofest.com)

• Access to URLs like http://guerdofest.com/gate.php, http://qweastradoc.com/gate.php, or fake Zoom downloads (Zoom.exe, ZoomInstaller.exe)

• Presence of droppers/DLLs (e.g., app_web_xlji1wtn.dll, app_web_c1tp5zym.dll, 7zipsfx.000zoom.exe)

Summary:

• Finding any human2.aspx, h2.aspx, or donotuse_human2.aspx (with matching hashes/sizes) on a MOVEit server = confirmed breach.

• Network traffic to the listed domains/URLs = post-breach activity (exfiltration or C2).

• Standalone hashes or other files = additional evidence, but web shells are the strongest breach indicator.

Scan MOVEit web directories (e.g., /MOVEitTransfer) for these ASPX files first if investigating potential compromise.

Below Is Full Resource File Including All Informations Related To IOCs Of Clop :

Download

Incident Response: What To Do If Clop Leaked Your Data

When an organization confirms involvement with the Clop ransomware group, the incident is already beyond a routine security event. A clop ransomware response is not just about containment it is about controlling fallout across legal, regulatory, reputational, and operational domains.

The most damaging mistakes in Clop incidents are rarely technical. They are timing, coordination, and assumption errors.

Incident Response Guidance for CL0P Exploitation of MOVEit Transfer (CVE-2023-34362)

If indicators from the provided block list (e.g., human2.aspx, h2.aspx, donotuse_human2.aspx, or matching hashes/domains) are detected on your MOVEit Transfer server, treat it as a confirmed compromise. Follow these structured incident response steps, primarily drawn from CISA Alert AA23-158A and related guidance.

1. Identification & Confirmation

• Scan MOVEit web directories (e.g., /MOVEitTransfer) for known web shells: human2.aspx (size ~6249 bytes), h2.aspx (~6428 bytes), upload.txt, UNAVAILABLE, or app_web_*.dll files.

• Use provided hashes (SHA-256/MD5) to match files via tools like VirusTotal, EDR, or hash scanners.

• Check logs for outbound connections to listed domains (e.g., zoom.voyage, connectzoomdownload.com), gate.php endpoints, or IPs.

• Deploy YARA rules (from CISA) to detect LEMURLOOT webshell activity (e.g., strings like "X-siLock-Comment", "MOVEit.DMZ").

• Audit database for unauthorized accounts: Run SQL query SELECT * FROM [database_name].[dbo].[users] WHERE Permission=30 AND Status='active' and Deleted='0' to identify CL0P-created admin accounts (Permission=30 is admin level).

2. Containment (Immediate Actions)

• Isolate the server: Immediately disable all HTTP/HTTPS traffic to the MOVEit Transfer instance (block inbound/outbound at firewall level). This prevents further exploitation or exfiltration.

• Block IOCs: Block listed domains, URLs, IPs, and hashes network-wide (firewall, DNS sinkhole, proxy).

• Preserve evidence: Create forensic images of the server, logs, and database before any changes.

• Disable compromised accounts: Delete or disable any unrecognized admin accounts found in the database.

3. Eradication

• Remove web shells and artifacts: Delete all matching malicious files (human2.aspx variants, DLLs, droppers like 7zipsfx.000zoom.exe).

• Rebuild or restore:

  • If possible, rebuild the MOVEit server from clean backups (do NOT restore from compromised backups).

  • If rebuilding, wipe the server fully—leaving the database intact may allow persistent CL0P accounts to remain.

• Apply patches: Update MOVEit Transfer to the latest version (Progress released fixes for CVE-2023-34362 and follow-on vulnerabilities like CVE-2023-35036). Verify patch status via Progress support.

4. Recovery

• Restore operations safely: Re-enable traffic only after patching, removing IOCs, and validating no persistence (e.g., re-scan with YARA/EDR).

• Monitor post-recovery: Watch for anomalous activity (e.g., unusual database queries, outbound traffic) for at least weeks.

• Reset credentials: Force password resets for all MOVEit users; implement MFA if not already in place.

• Backup validation: Ensure offline, encrypted, immutable backups are available and tested.

5. Post-Incident & Reporting

• Conduct root cause analysis: Determine how the vulnerability was exploited and why IOCs were missed.

• Report to authorities: Contact CISA (report@cisa.gov or 888-282-0870), FBI local field office, or ic3.gov. Do NOT pay ransom.

• Share IOCs: Report any new indicators to CISA for broader defense.

• Implement long-term mitigations: Enforce least privilege, network segmentation, continuous patching, EDR monitoring, and regular vulnerability scans.

How Dark Web Monitoring Helps Detect Clop Data Leaks Early

Dark web monitoring is critical for detecting Clop data leaks because the most damaging phase often occurs after the initial intrusion. Clop frequently steals data without deploying ransomware, triggering no endpoint alerts or encryption events. As a result, the first confirmation of compromise often appears externally, when leaked data becomes publicly discoverable and regulatory, legal, and reputational consequences are already unavoidable.

Effective Clop-focused dark web monitoring goes far beyond simple brand searches. It involves continuous surveillance of Clop leak sites, mirror infrastructure, underground forums, and early-stage chatter where stolen datasets, partial samples, or negotiation signals may surface. Because Clop follows a predictable extortion lifecycle, these indicators can provide days or weeks of advance warning before public listing and pressure escalation.