I didn’t see any pop ups while I was there or any email issues. The owner was surprised but I told her when a pop up does occur or there is an email issue, take a picture so I can tell what’s going on. I don’t think the computer is infected: she has Malwarebytes for Mac and it took only 10 seconds to run a quick scan and didn’t report any issues. That's the fastest I've ever seen Malwarebytes run on any PC including new ones. Plus I couldn't tell if it's up-to-date, look up any history on it or tell if it automatically runs in the background. But I'll accept it for what it is.
MBAM for Mac does not run in the background. It only scans when you run the program and manually initiate a scan. If you want a real-time malware/virus scanner, then you will need a full anti-virus program. There are a number of them available for Macs. I believe at least some of the free ones are like MBAM for Mac in that they don't have a real-time/background scanner, but I believe some do. Personally, I use Intego's VirusBarrier (actually also their firewall NetBarrier as well), which is a paid program. The biggest reason is the Intego effectively only does Mac anti-virus/malware/security products and has been doing so long before most of the other "big names" starting doing Mac products (with the exception of McAfee and Norton/Symantec).
And MBAM for Mac is not as extensive as the PC version. This is at least due to the fact that there is just a LOT less things to scan for on Macs than there is on Windows. There is frankly much more "bad stuff" out there for Windows, so MBAM for Windows has much more things to scan for. The other potential reason is that I don't know if MBAM for Mac does much more than scan for mostly adware since it started out as an anti-adware program. While the Windows version is not meant to be your only anti-malware/virus program on a Windows computer, I believe this is even more true on a Mac. FWIW, a scan of my computer using it lasted about a minute...which is WAY shorter than any Windows computer I have run a MBAM scan on.
It appears MBAM for Mac will automatically check to see if the signatures need to be update when you start up the program (I saw a brief flash of something indicating that when I started it up). You can also manually update the signatures under the "Scanner" menu in the program. You can also open a log from that menu, which will list the signatures used for the last scan, including the date of those signatures. And you can check for updates of the program itself under the "Malwarebytes Anti-Malware" menu.
Even without any real detailed information about what was happening, I also doubt there is any sort of infection. The biggest reason is that there is just way less "bad stuff" out there for Macs. It is only in the last year or two that any real malware for Macs actually started to show up "in the wild"...most of it was more proof of concept type stuff. There is so little threats out there that many Mac users don't even bother with anti-virus software (I DO NOT fall in the camp...I have been running AV software on my Mac since back before Mac OS X came into being, which back then there actually were quite bit of viruses for Macs). In addition, like Microsoft, Apple has added more built-in security into newer versions of the Mac OS. So, the reality is the actual malware infections are pretty rare still on Macs. Adware is a bigger possibility, but it is still rarer than it is for Windows computers.
My guess is that it likely just normal ad popup windows and normal spam tactics (i.e. "cold emailing" common email addresses, etc) that can just as easily effect Windows computers. If so, then an ad blocker and/or popup blocker Safari (or Chrome or Firefox) extension can deal with popup ads (I will note that Safari does have a setting in its Preferences that can block popup windows, but it will also block legitimate ones as well). And if spam is really an issue, then use of a spam filter (whether through the email provider's server side spam filter or one running on the Mac locally either built into an email client or independent) would likely be the best option (or just use the same spam filter I use...my delete key).
OS X version 10.9.5. Processor 2.3 GHz or 3.3 GHz I don’t recall. Intel core i5. RAM 4GB 1333MHz DDR3 Startup disk Macintosh HD
IMac 21.5” Mid 2011. Graphics AMD Radeon HD 6750M 512 MB. Software OS X 10.9.5 (13F1911)
Model name / Identifier iMac 12,1. Boot ROM version IM 121.0047.821. SMC version System 1.71f21.
SN system C02FGEKYDHJF. Hardware UUID 193793BC-12B2-5258-A3F1-EB2F81595ASF.
Here are issues I'm wondering about.
Somewhere in my evaluation of the computer I saw that there is a Free upgrade to Mac OS Sierra
--- This to me is what the computer needs: does this make sense?
Like what Microsoft has done, newer versions of the macOS do have more built-in security than the older versions. So, Sierra (which is 10.12) will have security updates compared to 10.9.5 (aka Mavericks) that the Mac is currently running. After all, 10.9 (aka Mavericks) was released about 3.5 years ago. Plus, Apple no longer supplies security updates to 10.9 (Apple's policy is to provide security updates to only the current version and the two previous versions, which at this time is 10.11, aka El Capitan, and 10.10, aka Yosemite). So, it will be more secure overall.
Now, whether it actually solves the issues that your friend is experiencing remains to be seen. After all, it will first really be a function of what issues he/she is experiencing and whether any updates to the macOS since Mavericks might help.
There is also the issue of whether or not new features might interrupt work flows. For the most part, there is not huge changes to the basic way the macOS works between Mavericks (10.9) and Sierra (10.12). There are a few things to be aware of, however. For one, Sierra introduces a bunch of features that commonly get lumped into what I will refer to as "storage optimization". These things include stuff like storing the Documents and Desktop folder on your iCloud drive (which means it is synced across Macs...kind of like Dropbox), have the macOS automatically store rarely used files on iCloud if your storage is maxed out, automatically empty the trash, get rid of duplicate and obsolete files, and automatically remove watched movies and TV shows from iTunes and your drive. While all these things can be really useful, they also can potentially be dangerous for a number of reasons, not the least of which is that it might require your to pay for more iCloud storage. It is these features that have caused me to hold of on Sierra...mainly because there have been instances of them being turned on by default after upgrading to Sierra and/or after updates to Sierra...and I don't want any of them on (theoretically, they all are supposed to be off by default, but the instances where they were not were bugs/errors). So, my point is the your friend should be aware of what the new features added in Yosemite, El Capitan, and Sierra were and whether or not any of those might be a problem...and also be aware of how best to set things up.
If your friend does not want to go all the way to Sierra, but still upgrade from 10.9, then that is more challenging. Generally, if you don't "buy" a new macOS version from the App Store (you have to "buy" it even though it is free) while it is the currently available version, then getting it becomes difficult. If you "buy" it while it is the currently available version, then it will show up under your "Purchased" tab in the App Store and you can download it even after it is no longer available by normal means on the App Store. If you have not bought it, then you typically have to call Apple's 1-800 store line to see if you can buy it that way, which would result in it showing up under your purchases. The exception seems to be with El Capitan. While El Capitan (10.11) will not show up if you open the App Store and search for it, supposedly this link should take you to in the App Store if you enter the link in Safari on the Mac:https://itunes.apple.com/app/os-x-el-capitan/id1147835434?mt=12
If it works, I would suggest that your friend "Get" (aka "Buy") it even if they do not want to upgrade to El Capitan. That way it will always be available under the Purchases tab. I would recommend the same for Sierra. I always "buy" the new macOS version, even if I am not ready to upgrade to it at that time. As a result, I have Lion (10.7), Mountain Lion (10.8), Mavericks (10.9), Yosemite (10.10), El Capitan (10.11), and Sierra (10.12), all the versions that were available through the App Store rather than physical media, available to download if I even want/need them (I also still have the optical discs of 10.0 through 10.6 around here somewhere...not that I necessarily still have computers that can run all those versions).
The last thing to note is that if you "buy" a macOS upgrade, it will download the upgrade installer to the Applications folder for the active user account and then automatically run the upgrade app. You can then either proceed with the upgrade or quit the upgrade installer app. If you quit the upgrade installer app, then it will remain in the Applications folder to be run at a later date. If you complete the upgrade now (or later), then the upgrade installer app will be deleted from the Applications folder. So, I tend recommend saving that installer file to another drive as backup so you don't need to download it again in the future.
Incompatible item and it appears it isn’t downloaded
--- IPhoto Apple version 9.6.1 released Mar 19, 2015
--- Is it because the computer isn’t upgraded to Sierra?
Yes and no. Technically, it is likely because it was not updated to Yosemite, which was released in 2014. Plus, if the Mac was running Yosemite 10.10.3 or newer, iPhoto would have been replaced by Photos anyway, a new photo management apps released by Apple with 10.10.3 in April 2015 (it is effectively a rebuilt/renamed iPhoto app and then Apple killed iPhoto, the consumer level app, and Aperture, the pro/prosumer level app).