How to eliminate Backdoor.SDBot trojan from the operating system

What is Backdoor.SDBot?

Backdoor.SDBot is a malicious program and (as its name suggests) is a backdoor trojan. Typically, the main goal of trojans of this type is to give the attacker access to an infected computer (by opening a 'backdoor' by connecting to an IRC channel) or to send commands to it.

The program was first released in 2002, however, cyber criminals continually release new updates. This trojan mostly targets Windows users. Note that Backdoor.SDBot is capable of updating itself by checking for newer versions on the web. It can cause serious problems and should be removed immediately.

More about Backdoor.SDBot

A trojan is software that is usually designed to operate silently. I.e., it is disguised as a supposedly legitimate process or software. People might not suspect that their computers are infected with trojans for some time.

There are, however, a number of symptoms that can help to detect the presence of Backdoor.SDBot: the operating system displays errors; it runs slowly; the system shuts down or restarts randomly; there are unknown processes running in the Task Manager or duplicate .exe (or other executables) files are created, or; unknown programs are running in the background. 

Backdoor.SDBot is designed to store files (executables) in system folders ("%System%") and the names of these vary depending on the trojan variant. Note, however, that the names are likely to be identical to genuine system files, which actually belong to the operating system. This trojan might be used to download and open/execute various harmful files.

Cyber criminals could use this technique to infect computers with other malicious software such as ransomware, keystroke loggers, cryptocurrency miners, and so on. Ransomware is software that is used to prevent victims from accessing their files by encryption. To regain access to their files, victims are encouraged to pay a ransom (purchase a decryption tool/key).

Typically, users who have computers infected with these programs experience data loss. If the system is infiltrated with a keystroke logger, it might be used to steal personal details such as banking credentials and passwords and logins of other accounts. Keystroke loggers record every key pressed on the keyboard.

Cyber criminals use these programs to steal information that might be used to generate revenue. Cryptocurrency miners use hardware (such as CPU, GPU) that is installed on victims' computers to solve mathematical problems, thereby mining cryptocurrency. Computers often become unusable or have reduced performance.

They also use more power, which leads to higher electricity bills. Trojans such as Backdoor.SDBot can also be used to infect the computers of other users. Furthermore, Backdoor.SDBot might be used to take screenshots (screen captures), thus allowing cyber criminals to steal personal information/details.

This backdoor trojan could be used to perform DoS (denial-of-service) attacks. These attacks are carried out to render machines or network resources unavailable to the intended users by sending multiple queries simultaneously - this eventually causes the target (e.g., the server) to crash, since it is unable to handle the volume of queries received.

Note also that Backdoor.SDBot can uninstall itself by eliminating all related registry entries. To prevent this situation, we recommend that you eliminate this trojan immediately.

Examples of trojans

Some examples of other programs categorized as trojans include Qakbot, Emotet, LokiBot, and Adwind. In most cases, people are unaware that their computers are infected with trojans. Cyber criminals use them to proliferate other malware, steal personal details, and cause damage in other ways.

Victims usually experience problems with finances/bank accounts, privacy, browsing safety, data loss, and so on. Therefore, take all measures to avoid having your computer infected with programs of this type.

How did Backdoor.SDBot infiltrate my computer?

Cyber criminals usually proliferate trojans and other malicious programs through spam campaigns, unofficial file or software download channels, fake software update tools, and software 'cracking' tools. Spam campaign proliferate computer infections by sending emails that contain malicious attachments (files).

These might be Microsoft Office documents, PDF or archive files (such as ZIP, RAR), executable files such as .exe, JavaScript files, etc. The main purpose of these campaigns is to trick recipients into downloading and opening the attached file. When opened, it triggers download and installation of a high-risk threat.

Untrustworthy, dubious software download sources such as freeware download websites, free file hosting sites, Peer-to-Peer networks (torrent clients, eMule, and so on) are used to disguise harmful software or files as legitimate. People who use these sources to download files or software risk to installation of computer infections.

Fake software update tools (updaters) cause damage when they download malware rather than updates, or they exploit bugs and flaws of outdated software. Some people use 'cracking' tools to bypass activation of paid programs/operating systems, however, they often download and install malicious programs instead.

How to avoid installation of malware?

To keep computers safe from ransomware, trojans, malware and so on, we recommend that you download, install, update software, and browse the Internet with care. Do not download files or software using dubious sources. Download from official and trustworthy websites only.

Update installed programs with implemented functions or tools that are designed by official software developers. The same applies to software activation. Use of 'cracks' and cracking tools is illegal and, furthermore, they are often the reason behind installation of malicious programs.

Attachments that are included in irrelevant emails should not be opened, especially if they are sent from unknown addresses. Prevent damage caused by malicious programs by regularly running scans with reputable (and updated) anti-spyware/anti-virus software.

If you believe that your computer is already infected, we recommend running a scan with Combo Cleaner Antivirus for Windows to automatically eliminate infiltrated malware.

Known names of files that can be used to disguise Backdoor.SDBot trojan (files are placed in the "%System%" folder):

Aim95.exe, CMagesta.exe, Cmd32.exe, Cnfgldr.exe, Explorer.exe, FB_PNU.EXE, IEXPL0RE.EXE, MSTasks.exe, MSsrvs32.exe, Mssql.exe, Regrun.exe, Svchosts.exe, Sys32.exe, Sys3f2.exe, Syscfg32.exe, Sysmon16.exe, YahooMsgr.exe, cthelp.exe, iexplore.exe, ipcl32.exe, quicktimeprom.exe, service.exe, sock32.exe, spooler.exe, svhost.exe, syswin32.exe, vcvw.exe, winupdate32.exe, xmconfig.exe

The Backdoor.SDBot trojan is designed to modify system options by adding the following rules/values:

• "Configuration Loader" = "%System%\iexplore.exe"
• "Configuration Loader" = "MSTasks.exe"
• "Configuration Loader" = "aim95.exe"
• "Configuration Loader" = "cmd32.exe"
• "Configuration Loader"= "IEXPL0RE.EXE"
• "Configuration Manager" = "Cnfgldr.exe"
• "Fixnice" = "vcvw.exe"
• "Internet Config" = "svchosts.exe"
• "Internet Protocol Configuration Loader" = "ipcl32.exe
• "MSSQL" = "Mssql.exe"
• "MachineTest" = "CMagesta.exe"
• "Microsoft Synchronization Manager" = "svhost.exe"
• "Microsoft Synchronization Manager" = "winupdate32.exe"
• "Microsoft Video Capture Controls" = "MSsrvs32.exe"
• "Quick Time file manager" = "quicktimeprom.exe"
• "Registry Checker" = "%System%\Regrun.exe"
• "Sock32" = "sock32.exe"
• "System Monitor" = "Sysmon16.exe"
• "System33" = "%System%\FB_PNU.EXE"
• "Windows Configuration" = "spooler.exe"
• "Windows Explorer" = " Explorer.exe"
• "Windows Services" = "service.exe"
• "Yahoo Instant Messenger" = "Yahoo Instant Messenger"
• "cthelp" = "cthelp.exe"
• "stratas" = "xmconfig.exe"
• "syswin32" = "syswin32.exe"

In addition, Backdoor.SDBot might modify the following Windows Registry entries:

• HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
• HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\
• HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\Run\RunServices

Files that might be created by Backdoor.SDBot trojan:

• %System%\SVKP.sys (Clean driver file that can be used for malicious purposes)
• %System%\msdirectx.sys (This file is designed to provide rootkit functionality and anti-virus suites detect it as Hacktool.Rootkit)

Known IRC servers used by the Backdoor.SDBot trojan:

• bmu.FL0W1NG.NET
• bmu.h4x0rs.org
• bmu.q8hell.org

The list of actions cyber criminals can perform using Backdoor.SDBot includes:

• Completely uninstall the trojan by removing the certain registry entries
• Download and execute files
• Dynamically update the Trojan
• Gather system/network information
• Manage the IRC client on an infected machine
• Manage the installation of the back door
• Perform Denial of Service (DoS) attacks
• Send the Trojan to other IRC channels with attempts to inject it into other machines

Example of a spam email used to distribute Backdoor.SDBot trojan:

Text presented within:

Subject: Certificate

Dear all,

Whatever you have suggested correction have been made please share your valuable suggestion before going to final print.

Thanks & Regards
*Kamal Kumar*
(Product Manager)

How to remove malware manually?

Most trojan infections can be removed by running a full system scan with Combo Cleaner. The full manual procedure below is for cases where automatic removal failed, where you want to verify a scan caught everything, or where the threat has multiple persistence points.

Tools you'll need

Combo Cleaner Antivirus 7-days free trial

Recommended primary scanner. VB100 certified. The 7-day free trial is available.

Microsoft Defender Offline Free · built-in

Built into Windows. Boots to a clean environment to catch rootkits.

Process Explorer Free

From Microsoft Sysinternals. Better than Task Manager - shows full paths and signatures.

Autoruns Free

From Microsoft Sysinternals. Lists every place malware can persist on your system.

Microsoft Safety Scanner (MSERT) Free

Official Microsoft on-demand scanner. Always-current signatures - expires every 10 days.

Phase 1~ 5 min

Contain - limit the damage

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1

Disconnect from the network

30 secNo tool needed

Unplug your Ethernet cable and turn off Wi-Fi. If you're on a laptop, the airplane-mode key works fastest.

Why this matters

Many trojans exfiltrate data - saved browser passwords, banking sessions, screenshots - and accept remote commands. Cutting the network stops both immediately. Keep it disconnected until Phase 4.

2

Boot into Safe Mode with Networking

3 min

Safe Mode loads a minimal set of drivers and stops most malware from auto-running. "With Networking" lets you download tools - re-enable Wi-Fi only after you've booted in.

Windows 11

Open Settings → System → Recovery. Click Restart now next to Advanced startup.

Your computer will restart into the "Choose an option" menu. Click Troubleshoot → Advanced options → Startup Settings → Restart. After the second reboot, press 5 or F5.

Windows 10

Click the Windows logo, hold Shift, click the Power icon and choose Restart. In the Choose an option screen, click Troubleshoot → Advanced options → Startup Settings → Restart. Press F5.

Windows 8

Go to the Start Screen, type Advanced, select Settings → Advanced startup options → Restart now → Troubleshoot → Advanced options → Startup settings → Restart → F5.

Note: Windows 8 reached end-of-life in January 2023 - running on it puts you at much higher risk of reinfection.

Windows 7

Click Start → Shut Down → Restart → OK. As the system boots, press F8 repeatedly until the Windows Advanced Options menu appears, then choose Safe Mode with Networking.

Note: Windows 7 reached end-of-life in January 2020 - running on it puts you at much higher risk of reinfection.

Phase 2~ 15 min

Identify - find what's hiding

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3

Inspect running processes with Process Explorer

Tool: Process Explorer5 min

Download Process Explorer from Microsoft Sysinternals. Run it as Administrator. Click Options → Verify Image Signatures and View → Lower Pane View → DLLs.

Sort by "Verified Signer." Anything unsigned running from %AppData%, %LocalAppData%, %Temp%, or %ProgramData% is suspicious. Right-click → Properties to see the full image path. Right-click → "Search Online" to look up unfamiliar process names.

Why not just Task Manager

Task Manager hides full file paths, doesn't show digital signatures, and groups processes in ways that make malware easy to miss. Process Explorer is the same tool Microsoft engineers use.

4

Map every persistence point with Autoruns

Tool: Autoruns 14.x10 min

Download Autoruns. Right-click Autoruns.exe and choose Run as administrator - without elevation, Autoruns can't inspect protected registry hives.

In the menu, open Options → Hide Microsoft Entries and Options → Hide Empty Locations, then click Refresh.

Modern trojans don't just live in startup. Walk through these tabs and look for unsigned or unfamiliar entries:

• Logon - classic Run/RunOnce keys
• Scheduled Tasks - frequent hiding spot, especially tasks with PowerShell, MSHTA, or rundll32 actions
• Services - unsigned services in non-Microsoft folders
• WMI - Event Subscriptions are a stealthy persistence mechanism (MITRE T1546.003)
• Image Hijacks - Image File Execution Options "Debugger" abuse
• AppInit - DLLs loaded into every GUI process
• Browser plug-ins - unsigned add-ons across all installed browsers

Pro tip

Right-click any suspicious entry → "Jump to Image" to see the actual file. Right-click → "Search Online" opens VirusTotal for the file hash. Don't delete yet - just write down the file paths and entry names. We'll remove them after the scans.

5

Check the hosts file and DNS settings

3 minBuilt into Windows

Trojans often redirect bank, antivirus, and update domains to attacker-controlled servers by editing the hosts file or DNS settings.

Hosts file: Open Notepad as Administrator and open C:\Windows\System32\drivers\etc\hosts. Legitimate entries are commented with #. Any uncommented IP-to-domain mapping is suspicious - especially redirects for microsoft.com, windowsupdate, or your bank.

DNS settings: Open Command Prompt as Administrator and run ipconfig /all. Confirm your DNS servers point to your ISP, your router, or a known public resolver (Cloudflare 1.1.1.1, Google 8.8.8.8). Then open Settings → Network & internet → [your adapter] → DNS server assignment and verify both DNS and DNS over HTTPS (DoH) settings haven't been hijacked.

Why this matters

A clean PC with hijacked DNS is still a compromised PC. You'll think you're at chase.com and you'll be at the attacker's clone.

Phase 3~ 60-90 min

Remove - three scans, one cleanup

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No single antivirus catches everything. The order below is intentional: offline scan first (catches rootkits before Windows fully loads), then on-demand scanners on the running system, then manual cleanup of anything they missed.

6

Run Microsoft Defender Offline

Tool: Built into Windows15 min

Reboot to normal Windows. Open Windows Security → Virus & threat protection → Scan options. Select Microsoft Defender Antivirus (offline scan) and click Scan now. Your computer will restart into a stripped-down environment and scan before the full operating system loads.

Why this comes first

Rootkits and bootkits hide from any scanner running on the same Windows session that's already infected. A pre-boot offline scan sees the disk before the malware can hide itself.

Recommended antivirus

Combo Cleaner

VB100 certified. Includes anti-trojan, registry/persistence scanning, anti-spyware in one pass. The 7-day free trial is available.

Download Combo Cleaner

7

Run Combo Cleaner full system scan

Tool: Combo Cleaner20-40 min

Install Combo Cleaner and run a full system scan (not the quick scan). Let it complete fully, review the detected threats, and apply the recommended actions. Combo Cleaner will quarantine known trojans and registry persistence.

8

Run Microsoft Safety Scanner as a second-opinion scan

Tool: Microsoft Safety Scanner15 min

Download Microsoft Safety Scanner (MSERT.exe), Microsoft's free on-demand tool. The binary expires every 10 days, which means every download has the latest signatures. Run a full scan after Combo Cleaner to catch anything one engine alone might miss.

Why a second scan

Different scanning engines catch different threats. Running an additional Microsoft scan after Combo Cleaner is the single most underused verification step in malware removal.

9

Manually remove anything still listed in Autoruns

Tool: Autoruns10 min

Reopen Autoruns. Anything you flagged in Step 4 that's still present hasn't been caught by the automated scans. For each remaining suspicious entry: right-click → Delete in Autoruns (this removes the persistence registration), then navigate to the file path and delete the actual file. Empty the Recycle Bin.

Important

Some malware files reappear after deletion because something else on the system recreates them. If you delete a file and it returns within minutes, you have a remaining persistence point that Autoruns didn't show - usually a service or scheduled task running under SYSTEM. Re-run the scans from Steps 6-8 or proceed to a clean install (see end of guide).

Phase 4~ 15 min

Recover - restore browsers and security

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10

Reset browsers and clear notification permissions

5 min

Trojans and adware frequently hijack browsers - change the default search engine, install rogue extensions, or grant themselves notification permissions to keep displaying scam pop-ups even after the malware is gone.

• Chrome: visit chrome://settings/reset and click "Restore settings to their original defaults." Then visit chrome://settings/content/notifications and remove any unfamiliar sites.
• Edge: visit edge://settings/reset. Then check edge://settings/content/notifications.
• Firefox: open about:support and click Refresh Firefox (Firefox uses "Refresh," not "Reset"). Then check Settings → Privacy & Security → Permissions → Notifications.

Review installed extensions in each browser and remove anything you don't recognize, especially extensions you didn't install yourself.

11

Re-enable Defender, Tamper Protection, and update everything

10 min

Many trojans disable security software. Open Windows Security → Virus & threat protection → Manage settings and confirm Real-time protection, Cloud-delivered protection, and Tamper Protection are all turned on. Tamper Protection prevents malware from disabling Defender silently.

Then run Windows Update (Settings → Windows Update → Check for updates) and update your browsers and applications. The infection vector that let the trojan in originally usually involves outdated software.

Phase 5~ 15 min + 7 days

Verify & secure

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12

Change passwords from a clean device

20 min⚠ Critical

If the trojan was an info-stealer (Lumma, RedLine, Vidar, and similar are extremely common), assume every password saved in your browser is compromised. Change them from a different, known-clean device - your phone is fine if it's not infected.

Recommended order:

1. Primary email first - it's the recovery hub for everything else
2. Banking and financial accounts
3. Password manager master password (if you use one)
4. Social media, shopping, and remaining accounts

Where available, enable phishing-resistant multi-factor authentication (passkeys / FIDO2 hardware keys / authenticator apps) - SMS-based MFA is bypassable by sophisticated attackers.

13

Verify the clean and monitor for 7 days

5 min + 1 week monitoring

Reconnect to the network and run one final full scan with Combo Cleaner. Open Task Manager (Ctrl + Shift + Esc) and switch to the Startup apps tab - confirm nothing suspicious has reappeared.

Over the next 7 days, watch for symptom recurrence: unexpected high CPU usage, unknown processes returning, browser redirects, or pop-ups. If anything returns, you missed a persistence point and the procedure needs to be repeated - or you may have a deeper compromise that requires a clean install.

When to clean install Windows instead

Manual removal isn't always the right answer. Reinstalling Windows from scratch is the only way to be 100% certain when:

• The malware reappears after every removal attempt
• A bootkit or UEFI rootkit was detected (this class of threat sits below the operating system and survives a normal Windows reinstall)
• A confirmed credential-theft trojan ran with administrator privileges (Lumma, RedLine, Vidar) - the system likely has multiple unknown payloads
• The PC is used for online banking, business email, or anything where partial doubt isn't acceptable

A clean install is a 30-60 minute process: Windows 11 reinstall via Settings → System → Recovery → Reset this PC → Remove everything → Cloud download. Back up documents to external storage first, scan the backup with Combo Cleaner before restoring it, and reinstall applications fresh - never restore them from a backup of the infected system.

Important: Manual removal requires advanced computer skills. If you're not confident identifying system files from malicious files, run an automated scan with Combo Cleaner and Windows Defender and stop there - that path catches the vast majority of consumer trojans without the risk of breaking Windows by deleting the wrong file.

Frequently Asked Questions (FAQ)

My computer is infected with Backdoor.SDBot malware, should I format my storage device to get rid of it?

Formatting your storage device will effectively remove the Backdoor.SDBot malware, but it will also erase all data on the device. Thus, running a system scan using a reputable security tool like Combo Cleaner is advisable to try to detect and eliminate the malware.

What are the biggest issues that malware can cause?

Malware can cause a range of significant issues, including data loss or theft, financial losses through identity theft or fraud, and compromised system stability leading to crashes or slowdowns. Additionally, malware can cause privacy breaches and additional computer infections.

What is the purpose of Backdoor.SDBot?

It is likely that cybercriminals use this malware to inject additional payloads, allowing them to encrypt victims' files, steal sensitive information, access files, capture screenshots, or perform other malicious activities.

How did malware infiltrate my computer?

It is known that Backdoor.SDBot is delivered via emails containing malicious attachments. Also, it may be distributed using vulnerabilities in outdated software or operating systems, P2P networks, malicious advertisements, compromised or deceptive web pages, infected USB drives, and similar methods.

Will Combo Cleaner protect me from malware?

Combo Cleaner can detect and remove nearly all known malware. Sophisticated malware often conceals itself deep within the system. Thus, users whose computers are infected with this kind of malware are advised to run a full system scan to ensure removal.