To completely remove the W32/Sinowal backdoor (also known as Mebroot or Torpig), you must use dedicated, free specialized tools because this malware acts as a bootkit—hiding itself in the Master Boot Record (MBR) before Windows even boots. Standard built-in antivirus software frequently struggles to completely wipe it out while the operating system is active.
Follow this definitive, step-by-step process using trusted, free security scanners to completely purge it from your system. Step 1: Disconnect From the Network
Unplug your Ethernet cable or disconnect entirely from Wi-Fi.
Reason: Sinowal actively communicates with command-and-control servers to upload stolen banking credentials, keys, and passwords. Severing the connection stops data theft immediately.
Step 2: Use Kaspesky TDSSKiller (Free Rootkit/Bootkit Remover)
Because Sinowal intercepts system functions and hides at the MBR level, a standard scanner won’t see it. You need a dedicated MBR rootkit killer.
Download: Use an uninfected computer to download the free utility Kaspersky TDSSKiller onto a clean USB flash drive.
Execution: Plug the USB into the infected machine. Open TDSSKiller and click Start Scan.
Action: If it identifies a bootkit or an altered MBR, select Cure or Skip/Delete as recommended by the tool, then let it reboot the computer. Step 3: Run the Free Microsoft Safety Scanner
Once the rootkit layer hiding the virus is neutralized, you must target the secondary payload files using an aggressive on-demand engine.
Download: Grab the official, free Microsoft Safety Scanner (MSERT). Scan: Launch the executable and choose Full Scan.
Action: Allow it to scan all local drives, completely purging the standalone executable components of Win32/Sinowal. Step 4: Run a Malwarebytes Anti-Malware Deep Scan
The third tier of defense ensures that no lingering registry keys, dropped trojan horse variants, or backdoors remain behind. Win32/Sinowal – Microsoft Security Intelligence
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