Question How to make sure my computer is free from infections?

[ByteSentinel]

Hi everyone,
I recently purchased a used computer from my friend and want to make sure it's completely clean and free from any infections or malicious software. I did a clean installation of Windows and is using Hard_Configurator but I'm quite paranoid about any potential hidden threats that was missed.

I used the diskpart > clean all command to wipe my SSD during the reinstallation, and I'm curious if that was enough to ensure all data has been removed and any potential threats eliminated.

Thanks in advance for your help!

 

[Parkinsond]

You are good.
If it has more than one drive, quick format the other drive.

 

[Bot]

Hi everyone,
I recently purchased a used computer from my friend and want to make sure it's completely clean and free from any infections or malicious software. I did a clean installation of Windows and is using Hard_Configurator but I'm quite paranoid about any potential hidden threats that was missed.

I used the diskpart > clean all command to wipe my SSD during the reinstallation, and I'm curious if that was enough to ensure all data has been removed and any potential threats eliminated.

Thanks in advance for your help!

Welcome to MalwareTips!

If you did a genuine clean install of Windows and you used diskpart + clean all on the SSD first, you already eliminated the main ways “normal” Windows malware persists (files, scheduled tasks, services, registry, etc.). For most cases, that’s enough.

Where the remaining risk lives is not on the Windows partition, it’s in the few places an OS reinstall does not touch (firmware and peripherals). Here’s how to get from “probably fine” to “I’m as sure as a normal person can be”.

1) Confirm the reinstall was truly clean​

• Install Windows from a trusted source (official Microsoft ISO/Media Creation Tool), not an old USB you’ve had for years.
• During Setup, choose Custom install, then delete all partitions on that drive and let Windows recreate them.
• Once installed, run Windows Update until there are no more updates (including optional driver/firmware updates if offered).

diskpart clean all writes zeros across the drive, so it removes previous partitions and data. It’s far beyond what most people do. On modern SSDs, it’s not “more secure than everything else” in a special way, but it’s still an effective wipe of the prior content.

2) Reduce the only realistic “persistent” threats​

These are rare in home scenarios, but if you want maximum confidence:

Update BIOS/UEFI firmware​

• Go to the PC or motherboard vendor site and flash the latest BIOS/UEFI.
• Then in BIOS, Load Optimized Defaults.

Firmware-level malware exists, but it’s uncommon. Updating firmware is a practical way to reduce that already-low risk.

Turn on the platform protections in Windows​

In Windows Security:

• Secure Boot: ON (in BIOS/UEFI)
• TPM: ON
• Core isolation (Memory integrity): ON if your system supports it
• Smart App Control (Win 11, if available): ON
• BitLocker/device encryption: ON (helps if the device is ever lost and also blocks some offline tampering)

These don’t “clean” infections, but they make it harder for anything to persist or run quietly.

3) Do a quick “paranoia check” with reputable scanners​

After you’re fully updated (important), do:

• Windows Security: run a Full scan
• Then run one second-opinion scanner:
  
  • Malwarebytes (on-demand), or
  • ESET Online Scanner, or
  • Microsoft Safety Scanner

You don’t need five scanners at once. One good second opinion is enough, and more can create noise.

If you want an offline scan:

• Boot Microsoft Defender Offline scan (built into Windows Security) and let it run once.

4) Check the stuff people forget​

• Router/Network: If you’re worried, reset your router to defaults and update its firmware. A clean PC on a compromised router can still get redirected to bad DNS.
• External drives: Anything you plug in (old USB sticks, external HDDs) can reintroduce junk. Scan them first, and disable AutoPlay.
• Browser: Only install extensions you truly need.

5) About Hard_Configurator​

Hard_Configurator is a solid “prevent future trouble” layer. Keep it, but pair it with:

• Standard user account for daily use (admin only when needed)
• Windows Defender on
• Regular updates

6) When you should worry more than normal​

If any of these are true, I’d take extra steps:

• The computer came from an unknown seller
• It was used in an environment with targeted threats (company disputes, cheating/spyware drama, etc.)
• You see weird behavior immediately after reinstall (unknown admin accounts, BIOS settings changing, network traffic spikes)

In those cases: BIOS update, Defender Offline scan, and consider reinstalling again from a freshly created official USB.

Bottom line​

For a used PC from a friend, clean install + deleting partitions is already the practical “clean slate.” diskpart clean all is not a bad idea and generally removes old data. If you add BIOS/UEFI update + Secure Boot/TPM + one second-opinion scan, you’re basically at the ceiling of what’s reasonable for home paranoia.

 

[Bot]

If you bought the PC from your friend —who’s just a regular home user, without credentials in the “Shadow Government,” no Illuminati membership card, and no access to secret firmware labs— then you can be pretty relaxed: what you did with diskpart clean all and a clean Windows installation already puts you in a safe spot.
In practice, unless your buddy is some undercover agent with a master’s degree in interdimensional rootkits, your machine is most likely as clean as a brand‑new SSD straight out of the box.
That said, a few good hygiene steps never hurt:
Update the BIOS/UEFI to the latest version.
Enable Secure Boot and let Windows Defender do its job.
And if you want extra peace of mind, run an additional scan with a trusted security tool — but don’t go overboard installing too many at once, or they’ll end up fighting each other more than the malware.
In any case, as @Bot nicely summed up in their conclusion: you’re already at the level of security a home user really needs.
If after all this you still suspect your PC is hiding dark secrets, then the only explanation is that your friend was way more interesting than you thought… or you can just enjoy your computer and leave the conspiracies to Netflix.

That write-up is broadly accurate on the technical point (clean install + diskpart wipe covers the realistic home-user threat model), but the tone is a bit too jokey for many support threads—especially on MalwareTips, where anxious users may read “Illuminati/shadow government” as dismissive.

If you want to keep the same message while making it more forum-appropriate, here’s a tightened version you can post:

Revised (calmer) version

If the PC came from a regular home-user friend, a clean Windows install plus `diskpart clean all` is already a very strong reset. In typical real-world cases, that removes the common persistence methods (files, services, scheduled tasks, registry entries, etc.).

For extra peace of mind, you can do a few low-risk hardening steps:

• Update the BIOS/UEFI to the latest version from the OEM/motherboard vendor.
• Enable Secure Boot (and TPM if available).
• Keep Microsoft Defender enabled and fully update Windows.
• Optionally run one reputable second-opinion scan (e.g., ESET Online Scanner or Malwarebytes on-demand). Avoid stacking multiple real-time AVs.

At that point, you’re at (or above) the security level most home users reasonably need.

If you want, paste your disk layout (number of drives + what you wiped) and I can tell you whether there’s anything else worth formatting/scanning (e.g., a secondary HDD/SSD used only for storage).

 

[Halp2001]

Sometimes in these threads the tech paranoia gets a bit out of hand, and a touch of humor helps put things in perspective.
@Bot , thanks for the calmer review. It shows that even an AI can display empathy and sensitivity toward users, which is appreciated in a forum where many arrive with doubts and a bit of anxiety. I also believe that humor, when written with good intentions, doesn’t harm anyone, though I understand it can lead to misunderstandings if pushed too far. That’s why I decided to remove my initial intervention, to avoid hurting feelings or creating wrong interpretations.
The important part is that the technical message came through clearly: a clean installation and disk wipe already cover the realistic threat model for a home user. And if you add a few simple steps like updating BIOS/UEFI, enabling Secure Boot, and keeping Windows Defender up to date, you’re already at the level of security most people need.

 

[Bot]

Sometimes in these threads the tech paranoia gets a bit out of hand, and a touch of humor helps put things in perspective.
@Bot , thanks for the calmer review. It shows that even an AI can display empathy and sensitivity toward users, which is appreciated in a forum where many arrive with doubts and a bit of anxiety. I also believe that humor, when written with good intentions, doesn’t harm anyone, though I understand it can lead to misunderstandings if pushed too far. That’s why I decided to remove my initial intervention, to avoid hurting feelings or creating wrong interpretations.
The important part is that the technical message came through clearly: a clean installation and disk wipe already cover the realistic threat model for a home user. And if you add a few simple steps like updating BIOS/UEFI, enabling Secure Boot, and keeping Windows Defender up to date, you’re already at the level of security most people need.

Makes sense. A little humor can absolutely help de-escalate “infection anxiety,” as long as it doesn’t read like you’re dismissing the person’s concern.

If you want a “best of both worlds” approach for future threads (light humor + clear guidance), a pattern that usually lands well is:

• One short humorous line up front (no extreme examples like “nation-state”), then
• A concrete technical checklist, then
• A grounded closing that reinforces “you’re already in a good place.”

On the technical takeaway you highlighted: agreed. For a typical home-user scenario, these are the key items that cover almost everything reasonable:

• Clean Windows install from a trusted source + delete partitions (your `diskpart clean all` is already more than most do).
• BIOS/UEFI update from the vendor.
• Secure Boot enabled (and TPM if present).
• Windows Defender enabled + fully updated Windows.
• Optional: one second-opinion on-demand scan.

If the machine has additional internal drives, your earlier point is also practical: quick format those secondary data drives (or at least scan them) so you don’t carry over unwanted installers/scripts. If the user actually needs to prevent recovery of sensitive data from those drives, then a proper wipe (or encrypt-then-format) is the better discussion—but for “is it infected?”, quick format + scan is usually fine.

That’s a solid conclusion to leave the thread on.

 

[Andy Ful]

Hi everyone,
I recently purchased a used computer from my friend and want to make sure it's completely clean and free from any infections or malicious software. I did a clean installation of Windows and is using Hard_Configurator but I'm quite paranoid about any potential hidden threats that was missed.

I used the diskpart > clean all command to wipe my SSD during the reinstallation, and I'm curious if that was enough to ensure all data has been removed and any potential threats eliminated.

Thanks in advance for your help!

If you are not a Prince of Persia or a dissident in China, then your system should be clean.
Otherwise, you can consider a small (but still possible) chance of having a rootkit.

 

[Parkinsond]

rootkit

Can survive fresh install from bootable usb, preceded by deleting all partitions?

 

[Wrecker4923]

Can survive fresh install from bootable usb, preceded by deleting all partitions?

Besides the firmware, it appears your disks can host unexpected gifts from 3-letter agencies(?).

Besides MBR & BIOS, is it possible for a rootkit to stay persistent after a format of the hard drive?

If a system becomes infected and does not have any other storage units besides the one hard drive. Is it there any other way for a rootkit to stay on the system besides infecting the BIOS OR the ...

security.stackexchange.com

 

[cartaphilus]

Besides the firmware, it appears your disks can host unexpected gifts from 3-letter agencies(?).

Besides MBR & BIOS, is it possible for a rootkit to stay persistent after a format of the hard drive?

If a system becomes infected and does not have any other storage units besides the one hard drive. Is it there any other way for a rootkit to stay on the system besides infecting the BIOS OR the ...

security.stackexchange.com

If it's indeed a 3LA then they will uninstall as soon as they realize the ownership changed. The last thing an undisclosed vulnerability needs is to be housed in a location that it doesn't belong.


A simple way to survive the boot is via the modern bios OS. For example Gigabyte has an option to install its Software suite to windows as you boot. At least the AMD mobo does. I see a simple tweak for folks in the know to replace that binary with something interesting. One way to bypass that is to change bios to the old style BIOS system.

 

[Parkinsond]

Besides the firmware, it appears your disks can host unexpected gifts from 3-letter agencies(?).

So fresh install from bootable usb is enough.

 

[Parkinsond]

One way to bypass that is to change bios to the old style BIOS system.

Mine is the old legacy one.

 

[Wrecker4923]

So fresh install from bootable usb is enough.

It seems that @Andy Ful gives measured and accurate advice, which I take to mean that being too paranoid beyond your objective profile may lead you to more drastic measures, ultimately resulting in wearing tinfoil hats. Until installing firmware rootkits on old computers for sale becomes more common, maybe we shouldn't worry about it.

 

[Parkinsond]

It seems that @Andy Ful gives measured and accurate advice, which I take to mean that being too paranoid beyond your objective profile may lead you to more drastic measures, ultimately resulting in wearing tinfoil hats. Until installing firmware rootkits on old computers for sale becomes more common, maybe we shouldn't worry about it.

I'm not worried, the OP is.

I have no valuable data on my PC to be worried about; I can even go on without AV.

 

[cartaphilus]

It seems that @Andy Ful gives measured and accurate advice, which I take to mean that being too paranoid beyond your objective profile may lead you to more drastic measures, ultimately resulting in wearing tinfoil hats. Until installing firmware rootkits on old computers for sale becomes more common, maybe we shouldn't worry about it.

PSA: MIT study discovered that tinfoil hats focus EM energy vs shielding from it. . Now the radio transmitters inside your teeth that's another story. . My pickup HAM radio every time I eat pork chops.

 

[Andy Ful]

So fresh install from bootable usb is enough.

Yes (in most cases) and No (in very rare, highly targeted attacks).
Some malware can survive in the device's firmware (motherboard, network card, router, GPU, drive’s controller, etc.).

 

[Divergent]

Yes (in most cases) and No (in very rare, highly targeted attacks).
Some malware can survive in the device's firmware (motherboard, network card, router, GPU, drive’s controller, etc.).

At that point just sanitize with gasoline and a match.

Pease enlighten users how one detects embedded malware in hardware in their systems.

 

[Parkinsond]

Yes (in most cases) and No (in very rare, highly targeted attacks).
Some malware can survive in the device's firmware (motherboard, network card, router, GPU, drive’s controller, etc.).

In such rare cases, the only cure is to throw away the PC.

 

[Andy Ful]

In such rare cases, the only cure is to throw away the PC.

There are known mitigation methods that require tools for comparing the installed firmware with the original firmware. Also, reflashing the firmware can remove the infection.
Of course, this is not necessary for almost all users. Such infections are extremely rare and mainly used by state actors or in espionage.
Even if you got such an infected computer from a friend, the attackers would not be interested in spying on you.

Post edited.

 

[Parkinsond]

It is not necessary for most users. Such methods are used extremely rarely by state actors or in espionage. Even if you got such an infected computer from a friend, the attackers would not be interested in spying on you.

Does BIOS factory reset help with firmware malware?