About The Installed M.D.A.'s Full Scan Finish Time Plus the End Results Of The MRT?

Question

I did a full scan with the installed M.D.A. and it ended up at 7 minutes 28 seconds for 258058 files?,is that normal in 2026?.I ask this question because before 2026 doing a full scan was a minimum of 3 hours.After the full scan was completed and nothing was found by the installed M.D.A,as shown on the screen.I checked the downloads folder to find the untouched dangerous downloaded downloads still there.I also did a full scan with the MRT and it also didn't find any threats either?,as shown on the screen.I explored a free program called (SuperAntispyware) and (MalwareBytes free) and using either one when used separately after the full scan was listing many dangerous downloaded downloads and where it was located?.A full scan by both of these two free programs was ending up getting it right?.I could not even understand why i can keep all dangerous downloads without limits, only by using the installed M.D.A. by itself,compared to the other installed free programs that totally blocked all dangerous downloaded downloads each time including installed ones,as shown on the screen.I could not once explore a/all dangerous download while the SuperAntispyware or MalwareBytes was installed,as shown on the screen,compared to the M.D.A on it's own that as i mentioned before was totally okay after fully exploring all kinds of dangerous downloads,that always doesn't end well.Please add ?,cheers.

Answer 1

A full Microsoft Defender Antivirus (MDA) “full scan” completing in about 7½ minutes for ~258,000 files is possible and not inherently a sign of a problem, especially on modern hardware and if:

• The disk is fast (SSD instead of HDD).
• Many files were already scanned recently and are unchanged.
• There are relatively few large archives (ZIP, CAB, etc.).

Documentation notes that full scans can take hours or even days depending on data size and type, but that is a worst‑case scenario, not a requirement:

• A full scan starts with a quick scan, then scans all mounted fixed disks and optionally removable/network drives.
• Duration is strongly affected by the amount of data, number of files, and especially large archives.

So the change from “3+ hours before 2026” to “about 7 minutes now” can be explained by changes in:

• Hardware (e.g., moving to SSD, faster CPU).
• Data volume (fewer files, fewer large archives).
• Configuration (for example, if some drives or locations are no longer mounted or included).

Regarding why Microsoft Defender and MSRT find nothing while other tools flag “many dangerous downloads”:

1. Different tools use different detection criteria
   • Microsoft Defender Antivirus and the Windows Malicious Software Removal Tool (MSRT) focus on known malware families and active threats.
   • MSRT in particular only targets a specific list of prevalent malware, not everything potentially unwanted.
   • Third‑party tools like SuperAntiSpyware or Malwarebytes often classify more items as “threats,” including adware, tracking cookies, and potentially unwanted programs (PUPs), which may not be classified as malware by Microsoft.
2. MSRT’s behavior
   • MSRT is designed to remove specific prevalent malware, not to act as a full real‑time antivirus.
   • When it detects malicious software, it may prompt for a full scan; that full scan can take several hours and scans all fixed and removable drives, but only for the families it knows about.
   • If MSRT finds nothing, it simply means none of its targeted malware families are present.
3. Defender’s scan types and coverage
   • Quick scan: checks locations where malware is most likely to start (registry, startup folders, mounted removable devices) and relies on real‑time protection for ongoing protection.
   • Full scan: quick scan plus all mounted fixed disks and optionally removable/network drives. It uses the security intelligence definitions available at the time the scan starts.
   • Full scans are generally not recommended to be scheduled regularly because real‑time protection plus quick scans are usually sufficient.
4. Why “dangerous downloads” can remain in the Downloads folder
   • If Defender does not classify a file as malware or a PUA/PUP based on its current definitions and policies, it will not remove or block it, even if another tool flags it.
   • Some items flagged by third‑party tools may be:
     • Tracking cookies.
     • Bundled installers.
     • Tools or scripts that are only risky in certain contexts.
   • Defender’s goal is to balance protection with avoiding excessive false positives.
5. Scan performance and “missed” items
   • A fast full scan does not automatically mean files were skipped; it reflects the amount and type of data and system performance.
   • If there are many large archives or limited memory, full scans can be slow or even fail; guidance suggests cleaning up large ZIP/CAB collections or excluding specific high‑volume folders in such cases.

If there is concern that Defender is not scanning everything expected:

• Confirm that the scan type is actually “Full scan,” not “Quick scan.”
• Check that all relevant drives are mounted and included.
• Ensure security intelligence definitions are up to date before scanning.
• Optionally run a custom scan on the Downloads folder specifically.

The behavior described—Defender and MSRT reporting clean, while other tools report many “dangerous” items—is consistent with different detection scopes and criteria, not necessarily a failure of Defender or MSRT.

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References:

• About scheduled quick or full Microsoft Defender Antivirus scans
• Antivirus and antimalware software: FAQ
• Troubleshoot problems with detecting and removing malware
• Remove specific prevalent malware with Windows Malicious Software Removal Tool (KB890830)
• Troubleshoot Microsoft Defender Antivirus scan issues