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Removal instructions for System Defender

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What is System Defender?

The Malwarebytes research team has determined that System Defender is a fake anti-malware application. These so-called "rogues" use intentional false positives to convince users that their systems have been compromised. Then they try to sell you their software, claiming it will remove these threats. In extreme cases the false threats are actually the very trojans that advertise or even directly install the rogue. This one also opens IE Windows to a porn-site. You are strongly advised to follow our removal instructions below.

How do I know if I am infected with System Defender?

This is how the main screen of the rogue application looks:


You may find this icon in your taskbar:


And see these warnings:





How did System Defender get on my computer?

Rogue programs use different methods for spreading themselves. This particular one was installed by a trojan.

How do I remove System Defender?

  • Please download Malwarebytes Anti-Malware to your desktop.
  • Double-click mbam-setup-version.exe and follow the prompts to install the program.
  • At the end, be sure a check-mark is placed next to the following:
    • Enable free trial of Malwarebytes Anti-Malware Premium
    • Launch Malwarebytes Anti-Malware
  • Then click Finish.
  • If an update is found, you will be prompted to download and install the latest version.
  • Once the program has loaded, select Scan now. Or select the Threat Scan from the Scan menu.
  • When the scan is complete , make sure that everything is set to "Quarantine", and click Apply Actions.
  • Reboot your computer if prompted.
Is there anything else I need to do to get rid of System Defender?

The rogue installs a proxy. You can remove this or revert to the old settings in Internet Explorer - Tools - Internet Options - Connections - LAN settings


Here you can remove the checkmark before "Use a proxy server for your LAN" or you can restore the settings to the previous situation. On most systems a checkmark should be placed before "Automatically detect settings".

Contact your system administrator if your are unsure what the old settings where.

How would the full version of Malwarebytes Anti-Malware help protect me?

We hope our application has helped you eradicate this malicious software. If your current security solution let this infection through, you might please consider purchasing the FULL version of Malwarebytes Anti-Malware for additional protection.

As you can see below the full version of Malwarebytes Anti-Malware would have protected you against the System Defender rogue. It would have warned you before the rogue could install itself, giving you a chance to stop it before it became too late.


Technical details for experts

Signs in a HijackThis log:

R1 - HKCU\Software\Microsoft\Windows\CurrentVersion\Internet Settings,ProxyServer = http= - HKCU\..\Run: [xcohutdw] C:\Users\MALWAR~1\AppData\Local\Temp\athdvwbitu\xcohutdw.exe
Note: the name, folder- and filename in the Run entry are random.


Alterations made by the installer:

File system details  ---------------------------------------------    In the new folder C:\Users\{username}\AppData\Local\Temp\athdvwbitu       Adds the file xcohutdw.exeRegistry details  ------------------------------------------    [HKEY_CURRENT_USER\Software\Microsoft\Internet Explorer\Download]       "CheckExeSignatures        REG_SZ, "yes" ==> REG_SZ, "no"       "RunInvalidSignatures"="REG_DWORD", 1    [HKEY_CURRENT_USER\Software\Microsoft\Internet Explorer\Main]       "Error Dlg Displayed On Every Error"="REG_SZ", "no"    [HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Internet Settings]       "ProxyEnable"= REG_DWORD, 1       "ProxyOverride"="REG_SZ", "<local>"       "ProxyServer"="REG_SZ", "http="    [HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Policies\Associations]       "LowRiskFileTypes"="REG_SZ", ".exe"    [HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Policies\Attachments]       "SaveZoneInformation"="REG_DWORD", 1    [HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run]       "yjnuwskt"="REG_SZ", "C:\Users\{username}\AppData\Local\Temp\ljykfhahsp\yjnuwskt.exe"    [HKEY_CURRENT_USER\Software\swudijyi]       "0"="REG_DWORD", 1414836625       "ozotehrr"="REG_DWORD", 0

Malwarebytes Anti-Malware log:

Malwarebytes Anti-Malwarewww.malwarebytes.orgScan Date: 11/1/2014Scan Time: 11:01:48 AMLogfile: SystemDefender.txtAdministrator: YesVersion: Database: v2014.11.01.03Rootkit Database: v2014.10.22.01License: FreeMalware Protection: DisabledMalicious Website Protection: DisabledSelf-protection: DisabledOS: Windows 7 Service Pack 1CPU: x86File System: NTFSUser: MalwarebytesScan Type: Threat ScanResult: CompletedObjects Scanned: 273211Time Elapsed: 3 min, 18 secMemory: EnabledStartup: EnabledFilesystem: EnabledArchives: EnabledRootkits: DisabledHeuristics: EnabledPUP: EnabledPUM: EnabledProcesses: 0(No malicious items detected)Modules: 0(No malicious items detected)Registry Keys: 0(No malicious items detected)Registry Values: 1Trojan.Agent.ED, HKCU\SOFTWARE\MICROSOFT\WINDOWS\CURRENTVERSION\RUN|xcohutdw, C:\Users\MALWAR~1\AppData\Local\Temp\athdvwbitu\xcohutdw.exe, Quarantined, [c5d2af87304c6acc555a1fbc7c85d52b]Registry Data: 0(No malicious items detected)Folders: 0(No malicious items detected)Files: 3Trojan.Agent.ED, C:\Users\{username}\AppData\Local\Temp\athdvwbitu\xcohutdw.exe, Delete-on-Reboot, [c5d2af87304c6acc555a1fbc7c85d52b], Trojan.Agent.ED, C:\Users\{username}\Desktop\1019aaa89a1025918e158aeedfb45404_b289da21ffd572ee4d5c9ff9593a8ece_undefined.exe, Quarantined, [cacda98d710bdb5b446bf6e54fb2936d], Trojan.Agent.ED, C:\Users\{username}\Desktop\xcohutdw.exe, Quarantined, [4750d6608defd95dcae503d82fd26a96], Physical Sectors: 0(No malicious items detected)(end)

As mentioned before the full version of Malwarebytes Anti-Malware could have protected your computer against this threat.

We use different ways of protecting your computer(s):

  • Dynamically Blocks Malware Sites & Servers
  • Malware Execution Prevention
Save yourself the hassle and get protected.
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