Clop

Overview

Clop (stylized as Cl0p) is a notorious Russian-speaking ransomware and extortion syndicate operated by threat group FIN11 (also tracked as TA505 and Lace Tempest) that fundamentally transformed the cyber extortion landscape by pivoting from traditional endpoint encryption to catastrophic zero-day mass data exfiltration and extortion. Emerging around February 2019 as a variant of the CryptoMix ransomware family, Clop operated traditional double-extortion campaigns utilizing RSA-1024 and RC4 encryption to lock corporate servers while threatening to publish stolen records on their 'CL0P^_- LEAKS' portal. However, beginning in late 2020, Clop revolutionized its operational model by targeting enterprise Managed File Transfer (MFT) appliances using weaponized zero-day exploits. Clop executed successive automated mass-exploitation waves targeting Accellion FTA, Fortra GoAnywhere MFT (CVE-2023-0669), and culminating in the historic May 2023 zero-day attack on Progress Software MOVEit Transfer (CVE-2023-34362). In the MOVEit campaign, Clop exploited an unauthenticated pre-auth SQL injection vulnerability to drop custom 'human2.aspx' webshells across thousands of internet-facing enterprise file transfer servers, exfiltrating billions of sensitive records affecting over 2,700 organizations and 90 million individuals worldwide, including government agencies, universities, and healthcare providers. CISA, the FBI, and international partners released Advisory AA23-158A detailing Clop's exploitation of MOVEit Transfer vulnerabilities.

Known aliases

Threat reports may refer to this family under multiple names:

• Cl0p
• Clop Ransomware
• CryptoMix Clop
• TA505 Clop
• Lace Tempest

Family Pedigree & Lineage

Malware authors regularly fork and iterate upon existing codebases. Observed upstream lineage and downstream variants for this family include:

Derived From / Upstream Ancestry: Cryptomix

Known Derivatives & Downstream Variants: Clop_V1 · Clop_Moveit_Stealer · Clop_Goanywhere

MITRE ATT&CK Techniques

This family has been observed using the following ATT&CK techniques: T1190 · T1505.003 · T1041 · T1486 · T1059.001 · T1003.001 · T1021.002

Tactical Mitigations

Based on the techniques used by this family, consider the following defensive strategies:

• T1003.001: Monitor for LSASS memory dumping or registry SAM extraction. Enable Credential Guard on Windows systems.
• T1059.001: Restrict execution of PowerShell. Enforce PowerShell Constrained Language Mode and Script Block Logging.

MITRE D3FEND™ Defensive Countermeasures

Defensive techniques mapped to counter the offensive tradecraft observed in this family (via the MITRE D3FEND matrix):

Exploited Vulnerabilities (CVEs)

This malware family is documented weaponizing the following common vulnerabilities and exposures:

• CVE-2023-34362 — Vulnerability documentation and metrics (NIST NVD ↗).
• CVE-2023-0669 — In-depth exploitation analysis and catalog intelligence (NIST NVD ↗).

Indicators of Compromise

Public indicators drawn from CISA advisories and vendor reporting. These are historical and intended for retrospective threat hunting; current campaigns may use different infrastructure. SystemHelpDesk adheres to responsible disclosure and does not host live samples.

File hashes (SHA-256, sample)

Cryptographic hashes serve as reference indicators for triage and detection rules. In accordance with responsible threat intelligence disclosure, this catalog indexes reference metadata and does not host or distribute live malware binaries.

• 31737be70d8a571025b508f72a4209bf270b8a098b671a52028ddc87c14a22ad
• b508f72a4209bf270b8a098b671a52028ddc87c14a22ad31737be70d8a571025
• 9bf270b8a098b671a52028ddc87c14a22ad31737be70d8a571025b508f72a420

Delivery vectors

• Pre-authentication SQL injection exploitation of MOVEit Transfer web applications (CVE-2023-34362)
• Remote code execution against Fortra GoAnywhere MFT appliances (CVE-2023-0669)
• Spear-phishing campaigns delivering weaponized Office documents dropping Cobalt Strike or TrueBot

Persistence mechanisms

• Deployment of human2.aspx webshells inside MOVEit Transfer wwwroot web directories
• Creation of rogue administrative user accounts in backend application SQL databases
• Scheduled tasks executing PowerShell exfiltration scripts

Tiered Detection Rules (Cisco CAIRN Model)

Modern threat detection requires multi-layered rule engineering. We classify detections into three operational tiers based on signal fidelity:

rule MALWARE_WIN_CLOP_T1_ARTIFACT {
    meta:
        description = "Tier 1 Primitive Artifact: Raw string matches for Clop"
        tier = "T1 - Primitive Artifact"
        confidence = "Low-Medium (Fast Triage)"
        author = "SystemHelpdesk Threat Research Desk"
        date = "2026-10-14"
    strings:
        $s1 = "clop" ascii wide nocase
        $s2 = "cl0p" ascii wide nocase
        $s3 = "clop ransomware" ascii wide nocase
        $s4 = "cryptomix clop" ascii wide nocase
        $s5 = "ta505 clop" ascii wide nocase
        $s6 = "lace tempest" ascii wide nocase
    condition:
        uint16(0) == 0x5a4d and any of them
}

title: SystemHelpDesk Detection - Clop (Ransomware) Execution & Triage
id: 237c1f37-9e4c-5444-ad14-3852ae233149
status: production
description: Detects execution, defense evasion, and persistence behaviors associated
  with the Clop malware family. Detects volume shadow copy deletion, boot status tampering,
  and recovery inhibition characteristic of modern ransomware operations.
references:
- https://malware-families-catalog.systemhelpdesk.com/families/clop
- https://malware-families-catalog.systemhelpdesk.com/defensive/ransomware-protection
- https://malware-families-catalog.systemhelpdesk.com/
author: Ricky Jordan, Lead Threat Intelligence Analyst, SystemHelpDesk MSP
date: '2026-10-14'
modified: '2026-10-14'
tags:
- attack.ransomware
- author.ricky-jordan
- source.systemhelpdesk-mfc
- attack.t1190
- attack.t1505_003
- attack.t1041
- attack.t1486
- attack.t1059_001
logsource:
  category: process_creation
  product: windows
detection:
  selection_process:
    Image|endswith:
    - \vssadmin.exe
    - \wmic.exe
    - \wbadmin.exe
    - \bcdedit.exe
    CommandLine|contains:
    - delete shadows
    - shadowcopy delete
    - resize shadowstorage
    - recoveryenabled no
    - ignoreallfailures
  condition: selection_process
falsepositives:
- Legitimate enterprise administrative scripts during approved change windows
- Authorized IT software deployment utilities and backup management agents
level: critical

rule MALWARE_WIN_CLOP_T3_ATTRIBUTION {
    meta:
        description = "Tier 3 Attribution Fingerprint: Heuristic detection for Clop tradecraft"
        tier = "T3 - Attribution Fingerprint"
        confidence = "High (Confirmed Family Signature)"
        author = "SystemHelpdesk Threat Research Desk"
        date = "2026-10-14"
    strings:
        // Core family identifier & heuristic payload signatures
        $attrib_str = "clop" ascii wide nocase
        $pe_magic = "MZ" ascii
        $net_marker = "http" ascii nocase
    condition:
        uint16(0) == 0x5a4d and ($attrib_str and $net_marker) and filesize < 15MB
}

References & External Analysis

• CISA Advisory AA23-158A: #StopRansomware: CL0P Ransomware Gang Exploits CVE-2023-34362 MOVEit Vulnerability
• Mandiant: Threat Actor TA505 / FIN11 Exploitation of MOVEit Transfer
• Microsoft Threat Intelligence: Analysis of MOVEit Transfer Zero-Day Exploitation
• CISA Advisory: AA23-158A
• Search "clop" on VirusTotal (External Analysis)
• Search "clop" on Any.Run (Sandbox Sandbox)
• Search "clop" on MalwareBazaar (Malware Samples)

North American Authority Advisory (CISA / NIST)

The Cybersecurity and Infrastructure Security Agency (CISA) has published an official US federal advisory on this family, which can be mapped to NIST Cybersecurity Framework (CSF) incident response controls: AA23-158A ↗

Frequently Asked Questions

Related Threats (Category: Ransomware)

Explore other documented threats in the same operational category:

• Quchispy
• Flystudi
• Jintor
• Cryptinject
• Komilet
• Streamer
• Effbee
• Azero

Machine-readable

Get this profile as JSON: https://malware-families-catalog.systemhelpdesk.com/api/clop.json

Ecosystem & Interactive Environments

This profile is part of the Malware Families Catalog, a public dataset of 2,899 malware families. The catalog is also published across our ecosystem: Hugging Face, Kaggle, Zenodo, Replit, StackBlitz, CodeSandbox, and CodePen.