Published Nov 10, 2010|Updated Sep 15, 2017

Trojan:Win32/FakeSysdef

Alert level: Severe Detected with Windows Defender Antivirus

Also detected as: 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.