Cwqw

Overview

Cwqw (identified across antimalware research as Ransom:Win32/Cwqw, Trojan-Ransom.Win32.Cwqw, and Ransom.Cwqw) is an evasive corporate crypto-ransomware family designed to execute destructive file encryption while actively impairing endpoint defenses. Distributed primarily via malicious loader networks and exploited network perimeter devices, Cwqw executes aggressive pre-encryption routines. Prior to encrypting data, the malware terminates an extensive list of targeted Windows services and processes, specifically targeting database servers (Microsoft SQL Server, MySQL, Oracle), mail servers (Exchange), hypervisors, and enterprise backup software (Veeam, Acronis). By forcibly terminating these processes, Cwqw unlocks restricted database handles and prevents automated backup systems from interfering with the encryption process. Cwqw then deploys high-speed symmetric stream encryption across all accessible drives, encrypting documents, databases, and code repositories, before deleting shadow copies and leaving extortion instructions demanding cryptocurrency ransom payment.

Known aliases

Threat reports may refer to this family under multiple names:

• Ransom:Win32/Cwqw
• Trojan-Ransom.Win32.Cwqw
• Win32/Cwqw
• Cwqw Ransomware
• Ransom.Cwqw

MITRE ATT&CK Techniques

Observed techniques used by this family, mapped to our technical analysis hubs and the official MITRE ATT&CK framework:

Tactical Mitigations

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

• T1105: Implement network intrusion detection systems (NIDS) and host-based firewalls to block unauthorized inbound or outbound file transfers.
• T1566.001: Scan email attachments for malicious macros, scripts, or suspicious archive files.

MITRE D3FEND™ Defensive Countermeasures

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

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_CWQW_T1_ARTIFACT {
    meta:
        description = "Tier 1 Primitive Artifact: Raw string matches for Cwqw"
        tier = "T1 - Primitive Artifact"
        confidence = "Low-Medium (Fast Triage)"
        author = "SystemHelpdesk Threat Research Desk"
        date = "2026-10-14"
    strings:
        $s1 = "cwqw" ascii wide nocase
        $s2 = "ransom:win32/cwqw" ascii wide nocase
        $s3 = "trojan-ransom.win32.cwqw" ascii wide nocase
        $s4 = "win32/cwqw" ascii wide nocase
        $s5 = "cwqw ransomware" ascii wide nocase
        $s6 = "ransom.cwqw" ascii wide nocase
    condition:
        uint16(0) == 0x5a4d and any of them
}

title: SystemHelpDesk Detection - Cwqw (Ransomware) Execution & Triage
id: 5bc16561-e0a8-56c2-a18c-5bbdfda7de50
status: production
description: Detects execution, defense evasion, and persistence behaviors associated
  with the Cwqw 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/cwqw
- 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.t1486
- attack.t1562_001
- attack.t1490
- attack.t1057
- attack.t1083
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_CWQW_T3_ATTRIBUTION {
    meta:
        description = "Tier 3 Attribution Fingerprint: Heuristic detection for Cwqw 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 = "cwqw" 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
}

Containment & Response Steps

Ordered checklist for responders. Adapt to your environment and engage professional support for active incidents.

1. Isolate the endpoint immediately to prevent Cwqw from downloading and executing its secondary payloads (e.g., ransomware).
2. Audit the Windows Task Scheduler and Registry Run keys to identify and remove the Cwqw persistence mechanisms.
3. Review firewall and proxy logs to identify the C2 domains Cwqw attempted to contact, and block them enterprise-wide.
4. Capture a live memory image (RAM dump) to extract the injected Cwqw modules and identify the secondary payloads.

What to Avoid

Common mistakes during response to this family that can destroy evidence, spread the infection, or worsen recovery.

1. Do not close an incident simply because the initial Cwqw dropper was quarantined; always verify if secondary payloads were downloaded.
2. Avoid relying solely on manual file deletion, as the injected processes will likely just recreate the dropped binaries.

References & External Analysis

• Microsoft Defender Threat Encyclopedia - Ransom:Win32/Cwqw
• Trend Micro Security Research - Ransom.Win32.CWQW Overview
• MITRE ATT&CK - Impair Defenses: Disable or Modify Tools (T1562.001)
• Search "cwqw" on VirusTotal (External Analysis)
• Search "cwqw" on Any.Run (Sandbox Sandbox)
• Search "cwqw" on MalwareBazaar (Malware Samples)

Frequently Asked Questions

Related Threats (Category: Ransomware)

Explore other documented threats in the same operational category:

• Bsymem
• Genericgb
• Bnqp
• Installbar
• Darsing
• Sadenav
• Wuca
• Cloverplus

Machine-readable

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