Winshow

Overview

Executive Summary

Infection Vector and Technical Capabilities

• Browser Extension Forcing: It installs malicious extensions or add-ons across all major web browsers (Chrome, Firefox, Edge). It often uses Group Policy Object (GPO) modifications in Windows to force-install these extensions and prevent the user from disabling them.
• Search Hijacking and Redirection: WinShow alters the browser's default search engine and homepage. Legitimate search queries are intercepted and routed through attacker-controlled domains to artificially inflate traffic metrics for affiliate programs.
• Content Injection: The adware actively modifies the HTML of legitimate websites the user visits, overlaying the page with intrusive pop-ups, banner ads, and in-text hyperlinks that were not placed there by the site owner.

Threat Assessment

Incident Response and Remediation

• Comprehensive Anti-Malware Scan: Utilize an enterprise-grade anti-malware solution capable of detecting and removing deeply embedded Potentially Unwanted Programs (PUPs), specifically targeting the persistent registry keys associated with the hijacker.
• Remediation of Group Policies: IT staff must inspect the local Group Policy settings (specifically Chrome/Edge enterprise policies) to remove any entries that are force-installing the malicious extensions.
• Browser Factory Reset: The most effective way to eradicate the hijacking components is to perform a complete factory reset of all installed web browsers, clearing all extensions, caches, and custom settings.

Known aliases

Threat reports may refer to this family under multiple names:

• Adware.WinShow
• BrowserHijacker.WinShow
• PUP.WinShow

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:

• T1185: Enforce strong MFA and use browser isolation or hardened browsers for sensitive financial or administrative portals to defeat session hijacking.

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_WINSHOW_T1_ARTIFACT {
    meta:
        description = "Tier 1 Primitive Artifact: Raw string matches for Winshow"
        tier = "T1 - Primitive Artifact"
        confidence = "Low-Medium (Fast Triage)"
        author = "SystemHelpdesk Threat Research Desk"
        date = "2026-10-14"
    strings:
        $s1 = "winshow" ascii wide nocase
        $s2 = "adware.winshow" ascii wide nocase
        $s3 = "browserhijacker.winshow" ascii wide nocase
        $s4 = "pup.winshow" ascii wide nocase
    condition:
        uint16(0) == 0x5a4d and any of them
}

title: SystemHelpDesk Detection - Winshow (Ransomware) Execution & Triage
id: 8249bcaf-66fd-521d-98cd-b092d52c4660
status: production
description: Detects execution, defense evasion, and persistence behaviors associated
  with the Winshow 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/winshow
- 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.t1562_001
- attack.t1185
- attack.t1112
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_WINSHOW_T3_ATTRIBUTION {
    meta:
        description = "Tier 3 Attribution Fingerprint: Heuristic detection for Winshow 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 = "winshow" 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. Immediately isolate affected host(s) from the internal network (disconnect physical Ethernet and disable Wi-Fi/Bluetooth) to prevent Winshow from spreading laterally or encrypting network-attached storage (NAS) and shared SMB volumes.
2. Preserve volatile system memory (RAM capture) on a representative endpoint before attempting a reboot or power-down, as Winshow symmetric encryption keys or uncompiled payload components may still reside in memory.
3. Audit process execution logs and terminate active scripting interpreters (e.g. PowerShell, CMD, WScript) or commands executing 'vssadmin.exe delete shadows' or 'wbadmin' used by Winshow to inhibit recovery.
4. Investigate the initial compromise vector (such as exposed RDP instances, spearphishing attachments, or vulnerable edge gateways) and enforce an immediate credential reset for all compromised Active Directory accounts.
5. Restore critical assets and databases exclusively from verified, air-gapped, or immutable offline backups once the Winshow binary and related persistence hooks are eradicated.

What to Avoid

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

1. Do not restart or power cycle infected systems prematurely; doing so destroys volatile RAM encryption keys and may trigger bootloader locking logic embedded in Winshow.
2. Avoid negotiating or paying the extortion demand without prior forensic evaluation and consultation with incident response specialists, as payment does not guarantee data recovery.
3. Do not connect clean backup drives or external storage to the affected network until Winshow eradication is completely verified.

References & External Analysis

• Search "winshow" on VirusTotal (External Analysis)
• Search "winshow" on Any.Run (Sandbox Sandbox)
• Search "winshow" on MalwareBazaar (Malware Samples)

Frequently Asked Questions

Related Threats (Category: Ransomware)

Explore other documented threats in the same operational category:

• Spook
• Sennoma
• Kradword
• Crypton
• Donn
• Baidu
• Gpukj
• Csom

Machine-readable

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