Published Nov 10, 2010 | Updated Sep 15, 2017


Severe |Detected with Windows Defender Antivirus

Aliases: PC Repair (other) TR/FakeSysdef.A.20 (Avira) Trojan.Inject.12360 (ESET) Mal/FakeAV-EA (Sophos) Trojan.FakeAV!gen28 (Symantec) HDD Defragmenter (other) Check Disk (other) Windows Repair (other) WindowsRecovery (other) Windows 7 Recovery (other) Windows XP Recovery (other) Data Restore (other) Disk Defrag (other) Disk Doctor (other) Disk Helper (other) Disk Ok (other) Disk Optimizer (other) Disk Recovery (other) Disk Repair (other) Disk Tool (other) Easy Scan (other) Fast Disk (other) File Recovery (other) Good Memory (other) Hard Drive Diagnostic (other) HDD Control (other) HDD Diagnostic (other) HDD Fix (other) HDD Low (other) HDD Ok (other) HDD Plus (other) HDD Repair (other) HDD Rescue (other) HDD Scan (other) HDD Tools (other) Memory Fixer (other) Memory Optimizer (other) Memory Scan (other) Quick Defrag (other) Quick Defragmenter (other) Smart Defragmenter (other) Smart Hdd (other) System Defragmenter (other) System Diagnostic (other) System Fix (other) Ultra Defragger (other) Win Defrag (other) Win Defragmenter (other) Win Disk (other) Win Hdd (other) Win Scan (other) Win Scanner (other) Windows Diagnostic (other) Windows Disk (other) Windows Fix disk (other) Windows Restore (other) Windows Safemode (other) Windows Scan (other) Windows Tool (other) Windows XP Restore (other) Windows 7 Restore (other) Data_Recovery (other) Data Recovery (other) SMART Repair (other) S.M.A.R.T. Repair (other) SMART Check (other) S.M.A.R.T. Check (other)


Windows Defender detects and removes this threat.

Win32/FakeSysdef is a family of programs that claim to scan for hardware defects related to system memory, hard drives and over-all system performance. They scan the system, show fake hardware problems, and offer a solution to defrag the hard drives and optimize the system performance. They then inform the user that they need to pay money to download the fix module and to register the software in order to repair these non-existent hardware problems. One of the first variants was distributed as program named "HDD Defragmenter" hence the name "FakeSysdef" or "Fake System Defragmenter".

NOTE: On March 31, 2017, an incorrect detection for our cloud-based protection for Trojan:Win32/FakeSysdef was identified and immediately fixed.

To ensure that this issue is remediated, you can do a forced daily update to download your Microsoft antimalware and antispyware software. The fix has been deployed in signature build 1.239.530.0 on March 31, 2017, 2:50 PM PDT.

See Updating your Microsoft antimalware and antispyware software for more information.


This program poses a high threat to your PC.

You might need to manually update your Microsoft security software.

After updating, make sure you run a full scan. Even if we've already detected and removed this particular threat, running a full scan might find other malware that is hiding on your PC.


Run antivirus or antimalware software


Use the following free Microsoft software to detect and remove this threat:



You should also run a full scan. A full scan might find hidden malware.


Additional instructions to remove Win32/FakeSysdef from your computer are available here:

How to remove the PC Repair virus

For more information on antivirus software, see

Additional remediation instructions for Win32/FakeSysdef:

This threat may make lasting changes to a computer's configuration that are NOT restored by detecting and removing this threat. For more information on returning an infected computer to its pre-infected state, please see the following article/s:

Use cloud protection

Use cloud protection to help guard against the latest malware threats. It’s turned on by default for Microsoft Security Essentials and Windows Defender for Windows 10. 

Go to All settings > Update & security > Windows Defender and make sure that your Cloud-based Protection settings is turned On.

Get more help

You can also see our advanced troubleshooting page or search the Microsoft virus and malware community for more help.

If you’re using Windows XP, see our Windows XP end of support page.