The cunning Winos 4.0 malware variant exploits deceptive NSIS installers to carry out multi-stage attacks. This malware even manipulates Windows Defender‘s security settings, creating exceptions that provide it room to operate. The dire consequences of these actions include data theft, registry tampering, and unauthorized surveillance of your PC activities.
Understanding the Dangers of Winos 4.0 Malware
The Winos 4.0 malware represents an advanced family of malicious software, tracing its roots back to Gh0st RAT. The “4.0”designation isn’t indicative of a specific version but reflects its classification within a broader category that has existed for over a year. Notably, on May 22, 2025, Rapid7 highlighted a Winos 4.0 variant utilizing VPN and browser installers to deploy its payload.
The malware initiates a chain reaction by deploying a bogus NSIS application, which acts as a corrupted executable file. Installer names are often innocuous, like QQBrowser_Setup_x64.exe or Lets.15.0.exe, benefitting from user trust. Such cunning deception tactics make Winos 4.0 particularly hazardous. Upon installation, it stealthily drops additional components, including a VBScript launcher, a PowerShell loader, a malicious DLL, and configuration files. Rapid7 aptly refers to this multi-stage payload as the Catena loader.
A significant feature of Winos 4.0 is its ability to maintain persistence through silent PowerShell commands that introduce exclusions to shield its payload. Astonishingly, this malware may lay dormant for weeks before activating, capturing passwords, cryptocurrency information, and manipulating the registry while monitoring screenshots, webcam feeds, and microphone audio. Operating entirely in memory, akin to Remcos RAT, this malware avoids detection by leaving no traces on your disk.
How to Verify Digital Signatures of Installers
To safeguard your PC, diligently checking the digital signatures of applications before installation is paramount. Right-click on the application, navigate to Properties -> Digital Signatures, then click Details -> View Certificate to verify the installer’s authenticity.
The image above illustrates checking the digital signature of QQBrowser, which, despite the availability of malicious variants with fake NSIS installers, bears a valid signature from Tencent Technology, the application’s legitimate developer.
Essential Windows Security Measures
Despite Winos 4.0’s cunning ability to deceive Windows Defender, there are ample steps you can adopt within the Windows Security app to bolster your defenses.
To prevent the execution of NSIS installers, launch PowerShell in administrator mode and execute the command below, which effectively reduces the Attack Surface Area (ASR) without implementing a blanket ban.
Set-MpPreference -AttackSurfaceReductionRules_Ids 3B576869-A4EC-4529-8536-B80A7769E899 -AttackSurfaceReductionRules_Actions Enabled
Next, access the Windows Security application. Navigate to Virus & Threat Protection -> Virus & Threat Protection Settings -> Manage Settings, ensuring that Real-time Protection is activated.
Furthermore, under Virus & Threat Protection, scroll to Manage Ransomware Protection. If Controlled Folder Access appears disabled, reactivate it. You may also whitelist trusted applications through the option Allow an App Through Controlled Folder Access.
Implementing these fundamental Windows Security protections is an effective first line of defense. Advanced users may also consider fortifying their firewall settings to specifically block Winos 4.0 malware.
Preventing Winos 4.0 from Making Exclusions in Windows Defender
One of the insidious tactics employed by Winos 4.0 is the formation of exclusions within Windows Defender scanning protocols. You can take proactive measures to impede this threat.
Open PowerShell in administrator mode and use the command below to add execution policies that restrict harmful scripts. Flash A to confirm.
Set-ExecutionPolicy -Scope CurrentUser -ExecutionPolicy Restricted
To restrict unauthorized exclusions across all drives, execute the following command in PowerShell:
Remove-MpPreference -ExclusionPath C:\, D:\, E:\, F:\, G:\, H:\, I:\, J:\, K:\, L:\, M:\, N:\, O:\, P:\, Q:\, R:\, S:\, T:\, U:\, V:\, W:\, X:\, Y:\, Z:
Detecting Fake NSIS Entries with Autoruns
Employing a Microsoft tool called Autoruns can help track undesirable startup programs, including suspect NSIS entries. This method is among the most effective ways to identify Winos 4.0 and prevent its execution.
Start by downloading the Autoruns ZIP file from the Sysinternals webpage. Installation is unnecessary; just unzip the file and double-click on Autoruns64 (for Windows 64 systems).This gives you an overview of active logons, scheduled tasks, and processes. Look for entries flagged in red and closely monitor any NSIS-related entries that will be highlighted.
Legitimate Windows app installers often escape suspicion. Once they navigate through SmartScreen (which should remain enabled) and pass Windows Security checks, users often presume that these applications are safe—this assumption provides a gateway for Winos 4.0 malware. Ensuring robust shielding for your PowerShell window by restricting script executions can vastly improve your defense. Leverage services like VirusTotal to analyze installer packages for potential malware threats.
Frequently Asked Questions
1. What is Winos 4.0 malware and how does it infect my system?
Winos 4.0 is an advanced form of malware derived from Gh0st RAT, typically infecting systems through deceptive NSIS installers disguised as legitimate applications. Once installed, it can execute a multi-stage attack leading to data theft and surveillance.
2. How can I protect my computer against Winos 4.0 malware?
Protect your computer by verifying the digital signatures of all installers, enabling Windows Security protections, preventing unauthorized exclusions in Windows Defender, and using tools such as Autoruns to detect suspicious entries.
3. What are the signs that my computer might be infected with malware?
Signs of infection may include unusual system slowdowns, unrecognized programs at startup, unexpected behavior from installed applications, or frequent system crashes. If you suspect infection, it is crucial to scan your system with reliable antivirus software immediately.
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