Is it Safe to Buy a Used Computer?

Category: Hardware

In today’s age of rampant malware, would you buy a used computer being sold at a thrift store, on Ebay, or Craigslist? How about a refurbished computer offered by Dell, HP, or another well-known vendor? What about a used hard drive, memory module, printer, or even a mouse? Is it ever safe to go with used tech hardware? Read on for my advice...

When Is Used Hardware Safe?

People buy used cars every day, with the understanding that something could go wrong. If you're lucky, you might get a limited warranty from a dealer. But if you buy from a private individual, it's a "buyer beware" situation, and you hope for the best. Of course, many items are sold online as "used" or "reburbished" and things work out just fine. But you'd be surprised how much returned (and sometimes defective) merchandise is being sold online as "new." I'll be publishing an eye-opening article on that topic soon.

But what about computer gear? Is there a chance that malware could be lurking in a used computer, a hard drive, or even a printer? What about state-sponsored spy organizations implanting spyware in the computer supply chain? Such questions are not raised only by the tinfoil-hat crowd. The most cursory attention to security-related tech news finds examples of even brand-new hardware being infected with malware. If the culprit can be found, it’s usually a disgruntled or careless factory employee who allowed malware into the production line. How much more vulnerable is used hardware?

Any computer that has been used by someone else is suspect, because anyone - no matter how security-conscious - may allow malware to slip into his/her system. Refurbished gear is guaranteed to be restored to factory-specified performance levels. But that means the machine performs adequately on benchmark tests. It does not, necessarily, mean that it has been scanned with a good anti-malware utility, let alone thoroughly cleansed of any malware. When shopping refurbs, be sure to ask specifically about malware scanning, including names of anti-malware software used and what components are scanned.

Buying a Used Computer - Is it safe?

Don’t expect refurbished gear’s limited warranty to cover undetected malware delivered with the refurbished hardware. Even if you can prove you found the malware almost immediately after opening the box, it will be an uphill battle to convince a vendor that you were not the source of the infection.

I would not trust any seller or giver of used computers, from a stranger on Craigslist to my family’s “IT geek.” OK, I might trust the latter, because he is me! That’s my point: trust only yourself to do a proper job of checking used gear for malware, and do the job properly.

Before plugging anything into any “new” used computer - including allowing it to connect to your WiFi network - you should boot it from a rescue disk that does an automatic anti-malware scan. You can made a rescue disk with Windows or your anti-malware program. If you haven’t made such a disk, do it before you need it! Here are instructions for the AVG Rescue CD and the Windows Defender Offline disk. You can find other options here.

Running blindly with a used computer is kind of like moving into a fully-furnished abandoned house. Would you sleep on a bed that might be harboring bed bugs or dust mites? Would you sit on that dirty old couch?

Another option when purchasing a used or refurbished computer is to toss the hard drive. Install a new hard drive, and either restore your files from a backup, or start from scratch with a Windows installation disk. Did the previous owner fail to apply security patches, use anti-virus tools, and keep software up to date? Did he download stuff from dark corners of the Internet? You don't want to inherit someone else's problems.

RAM (memory) modules should be safe. When they’re without power, they lose all data stored on them, including any RAM-resident malware. However, that is not true for firmware chips such as those embedded in printers and other peripherals, including graphics cards that may be inside a used computer. Firmware chips retain their contents even without power.

A mouse does not contain any writable memory, not even firmware. A mouse is driven by the driver software that is installed on a computer. I would not trust a USB flash drive full of “mouseware” that might accompany a used mouse. I would download the latest version of the compatible software from the manufacturer’s site, not a third-party software repository.

What About Other Gadgets?

For that matter, I would not trust any USB flash drive or external storage device that I didn't purchase brand new myself. Aside from the fact that a careless person might be passing along an infected USB drive, it's a well-known tactic for bad guys to load malware on USB drives, and "accidentally" leave them where someone might find them. Under the right conditions, simply inserting an infected drive into a USB slot will transfer a virus to your computer.

A used printer contains plenty of writable memory in which malware can lurk. Most modern printers require bi-directional communication with the host PC, meaning the printer can transmit data to the PC. That data may include malware, so treat your “new” used printer as a potential threat. It does seem unlikely, but this article from Computer Weekly details how it can happen.
For the first month or so after acquiring it, keep your PC’s shields at their highest sensitivity, and scan for infections daily. Better some false positives than a malware infection that was timed not to go off until you became complacent.

I would not buy a used “Internet of Things” device at all. Every one of them contains writable memory in which malware can hide, and there is presently no satisfactory way to scan IoT things for malware. Whether it’s a Chromecast dongle, a "smart" appliance, or a relatively cheap smart light bulb, I would buy a new one.

Sorry if I seem overly negative on buying used or refurbished computer equipment. But you can (for example) buy a new desktop PC from Dell, HP or Acer for about $350, with 4GB of RAM and a 1-terabyte hard drive. How much will you save, after buying a junker and upgrading the hard drive? Your thoughts on this topic are welcome. Post your comment or question below...

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Most recent comments on "Is it Safe to Buy a Used Computer?"

(See all 32 comments for this article.)

Posted by:

Renaud Olgiati
28 Jan 2019

I recently had to deal with around 20 computers left over when the French Consulate in Asunción closed, and those were given to the Alliance Française language school.

I dealt with them by the simple expedient of booting each with a DBAN live disk, and completely wiping the disks before re-formating them as ext4 and installing Linux.

Problem solved.

Posted by:

28 Jan 2019

I buy used stuff all the time, from cars to furniture, EXCEPT for electronics! You get so much more for your money when buying a new device with the latest capabilities, over anything used and older than a year or two. However, a relatively new device that has been factory refurbished is probably OK.

Posted by:

28 Jan 2019

I too have purchased Refurbished PCs from reliable companies. I have been purchasing these PCs from a company called They go over the PCs that they get from either Dell or HP. These PCs are "Off-Lease" computers and they have a 6-month warranty with them. The 6-month warranty has been a part of their company's policy for over 15 years.

I am using a Dell Optiplex 960 that I bought from them in Sept. 2013. Yes, there were some blemishes but, that never bothered me. Every one that I have gotten from them has been wonderfully package for shipping. All of them have had "sprayed foam" around the Mini Towers. They have worked right from getting them out of their shipping boxes.

I have saved many dollars for myself, as well as family and friends. Right now, my PC is technically 11 years old, but it is still kicking and works just fine. I got a Refurbished one for my Hubby and his PC is fine, too. His is a Dell Optiplex 760, with a 500 HDD, 8MB Memory and it came with Win 7 Pro. I have upgraded his, to Win 10 Pro.

Right now, my PC is a Win 7 Pro. I had to go back to the original MS Operating System since the last Update of Win 10 Pro really did a number on PC. I was getting BSODs when I haven't had them since forever, it seems. I am debating whether or not I want to get Win 10 Pro again. I use my PC more than my Hubby does, he mainly plays 2 games Mahjongg and Bejeweled 2 or 3. He does like to play Solitaire now and then. But, everything on his is working fine.

Newegg also has Refurbished PCs that have a Microsoft Warranty for 1 full year. Now, for a Used PC that is probably an "Off-Lease", that really is a good bargain.

Yes, you must be very, very careful when you are looking at Used or Off-Leased PCs. I would not get any from E-Bay or Craig's List. I just got one from Newegg for my grandson for $155 plus $3.99 shipping. It was a great deal and he is using his to work in conjunction with his X-Box One, for playing his favorite games.

I have also gotten Discontinued Motherboards when I have built my own. I get good deals on them and they are brand new with all the bells and whistles. I have been a user of discontinued and refurbished products since 1997. I don't need the latest and greatest components to be a Happy Camper. I just want something that is "newer" than my last PC.

Now, this has been my experience and if, you do know what you are doing ... You can find great bargains.

Posted by:

28 Jan 2019

Oh no! I've bought and sold laptops from Craigslist for years. Hard drives and memory from Ebay. Twice i didn't get what i paid for.(Not much lost). Otherwise, mostly bargains. Latest buy was a DELL 14" Windoz 7 Pro quad core laptop but only a 160GB hard drive for $75. From a hobbyist stranger. Sometimes i have to push the start button harder (twice) to cold start it. To this i installed Used 8 GB DDR3 memory off Ebay for $23. And a new WD Black 7200 rpm, 500 GB hard drive for $30. Most items include the purchase of a Square trade warranty for little money. Buy new? Some items.

Posted by:

Bill Pfeifer
28 Jan 2019

I volunteer at a homeless shelter, where we get donated computers with unknown history.
I sanitize the hard drive with hdderase (, which uses the Secure Erase command built into the drive's firmware. Takes a looong time, but it fully wipes everything, even data unaccessible through software, such as bad blocks. Then install Win 10; if it activates, great. If not - next!

Posted by:

28 Jan 2019

STOP TOSSING HARD DRIVES! Assuming the hard drive is not broken, performing a Diskpart clean command or just deleting all the partitions will remove everything from a hard drive including any possible malware.

Boot from a Linux or Windows installation flash drive or DVD and take the option to delete all partitions and/or erase the disk.

Posted by:

28 Jan 2019

Staples and New Egg offer a lot of refurbs. I decided to go to the source which I learned about in the comments and called them, the company that does the refurbushing. The person I spoke to was terrific and provided me with the link to New Egg for the machine he quoted me on, a ThinkPad. I only use it occasionally but so far it's fantastic. And it was a g r e a t price.

Posted by:

Charlie Keebler
29 Jan 2019

Greetings Bob!
You mention the "AVG Rescue CD". However, going to that site and trying to download the image results in a "404". Searching the website for the download provided no joy.
Thanks for your newsletter.
- Charlie

Posted by:

29 Jan 2019

If you are that paranoid you should know gaming mice have flash memory in them to save the settings. I personally have no problem with used computers or other related hardware. A few precautions is all it takes to protect yourself. I tend to avoid used hdd's but that is because I don't know when it will fail.

Posted by:

Greg c
29 Jan 2019

AVG Rescue CD appears to have been retired. The links to this CD do NOT work and I could not find much reference to it on AVG site.
I was able to find mention of it in this post (May 2018) and even this link will no longer work:
"AVG Rescue CD ( is very old and not maintained so we recommend it's usage only if none of the other methods worked."

Posted by:

Bob K
29 Jan 2019

About the only way to way to get a computer these days with Win 7 on it is to latch on to a used one. A couple of refurbished boxes from Newegg have been great buys, very nicely cleaned up -- and no malware.

Posted by:

29 Jan 2019

I like the smell of new [ummmm...] hardware!
I also enjoy building my own systems with newest gear that have all of the latest tech-acronyms.
I am willing to pay a 'bit' extra to get ruggedness. This allows me to learn and figure out all of the latest whizzbang features, which [unfortunately] keep loyal to Moore's Law.
After about 36 months, these hardware are re-purposed for friends or a relatives.
While building up an Intel NUC8i7 for last Christmas, I have come to realize that the end is near for this enjoyable pastime of the last 40+ years. Soon, a "used computer" is going to become as disposable as [errrr...] used toilet-paper.

Posted by:

29 Jan 2019

@ Bob Rankin,

Thanks for the good advice.

@ Renaud Olgiati

Please avoid going to the Softonic website
(like for dban etc ) They are notorious for bundling the software with all kinds of crap.

As for me. I've been very lucky over the years buying secondhand computers. IBM,Dell and HP.
Every one of them looked like new - factory reconditioned. of course I check everything
and have the knowledge to boot.
Never found any problems.

Posted by:

29 Jan 2019

I have dealt with secondhand computer hardware for years and never had any problems. You just need to be aware of the traps/pitfalls and take the necessary steps. I have purchased second had RAM off eBay and other similar sites with no issues. One dramm did not work so just returned it bwith no hassles. eBay’s buyer protection is great.. i also recently scored a s/h ‘firecuda’ 1tb hybrid drive for $30 (the seller upgraded to a full SSD), here in Australia they are over $100 new. Installed and works fine running Win 10.

Posted by:

29 Jan 2019

I have bought several refurbished Lenovo laptops from an Amazon (UK) reseller, reformatted and installed Linux to provide my children and wife with a good quality tough(er) machine at a reasonable cost. (Lenovo because of great Linux support.) We have never had any issues, the battery isn't covered on any warrantee but they are mainly used in their rooms plugged in. Currently preferred option is the T410 and Mint 19.1.

Posted by:

29 Jan 2019

Thank you Bob, I'll have to rethink my policy of buying second hand kit, now that malware is so prevalent. Those folk objecting to binning old drives overlook the fact that many will have had hard use for some years, and will be much nearer their fail-by date than a new drive.
Several UK companies selling ex-business computers install new drives as a matter of course; now I understand their motives.
You did not mention backing up your computer before plugging in any second hand kit, but I suppose anyone reading your articles will have taken that as read!!

Posted by:

29 Jan 2019

I bought a laptop from a pawn shop and discovered that a mysterious admin had locked out all software installations, including new antivirus programs. It also would not run the antivirus that was installed. Nor would it run any utilities. I pulled the hard drive and hooked it up to an external drive dongle on my other computer and wiped the drive then repartitioned and reformatted it. Installed a clean Windows install and it worked for a couple of years for me, till I found a really good price on a new laptop.

Posted by:

29 Jan 2019

I have purchased 4 refurbished computers, all with good luck and substantial savings. On all, I upgraded the hard drive with a new one and ran the usual anitvirus/malware programs. I continue to use these computers some 3 years later.

Posted by:

Mike Davies
30 Jan 2019

I lent a Sandisk USB stick to a pal, it had various documentaries on it which he was interested in watching, all scanned and cleared OK. He transferred the data to his laptop and viewed the shows, no problem.
He then lost the USB stick and said "I'll replace it".
He bought one off the net from China - he's not very computer-savvy at all.
So, he gives me the stick, which had no labels or markings on, just "8 GB" on it.
Oh dear, but no problem.
I set up Avast to do a pre-boot scan, turned off my laptop, plugged in the new USB stick, and then turned on the laptop.
The pre-boot scan started, showing me its progress on a black and white screen.
After a while it finished.
I don't recall what the answer was, but when I checked the properties of the US stick it showed the memory as only 5 GB, not the supposed 8 GB.
So 3 GB of crapware, spyware, malware or whatever had been deleted.
Also, after this process, the USB stick was virtually unusable.
The lesson is, only buy such stuff from recognised reliable suppliers.

Posted by:

Skeeter Sanders
04 Feb 2019

Bob -- Are you saying that simply doing a clean reinstall of the operating system won't wipe out any malware that's on a used computer?

I thought that to do a clean reinstall of the OS will "overwrite and erase anything that's previously on the hard drive -- much like re-recording on an old audiotape or videotape will overwrite and erase anything that was previously recorded on it.

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