To be clear, "validating" is an industry euphemism for stealing, just for a different purpose. How do you validate the card is live? Run a real transaction through it and mark it based on the result. But what do you run for this real transaction? Well, whatever you want. Typically it'll be something to avoid suspicion as much as possible, but the thief gets to pick what they test it with, so why not pick something that they'll personally benefit from? There are so many online games with purchasable currency these days, it's hard to choose.

They won't cash out on them or buy items. Instead, they'll collect cards from a source (skimming, hacking, whatever), validate them by adding them to a website that does an authorization (those $1 checks that never get committed). They can then sell them wholesale for a premium compared to non-verified cards.

I've been away from that world for a while but remember that more serious operations will separate the cashing out part (either money or goods) from their acquiring / validating operation because the former carries more risk.

There's also an interesting episode of the darknet diaries podcast (https://darknetdiaries.com/episode/85/) about card cloning which I found interesting.

Not necessarily. Some online services, particularly shops that do home delivery, may give their customers the possibility of adding a card to their wallet and perform a verification as part of the process. As a result, it becomes possible to validate a stolen card number without performing an actual transaction.

The most amusing to me are the ones from “Microsoft” to alert me that they have detected malware on my computer.

And yet if you dare browse the web with TOR or a VPN or sometimes just happen to be on a small ISP[0][1] then you're being punished immediately. You solve your cloudflare-supplied captcha because you may be a bot (you're not, and the dangerous bots will not be defeated by this anyway, but some humans will be), and then you get an error from the website itself because it runs a secondary bot detection thing. And you weren't even anywhere near anything "dangerous" like a checkout page.

[0] My parents use a regional small ISP (but locally very popular) that serves around 50K customers. My parents also use a regional bank (a Volksbank, and those are members of a national association that provides all kinds of services). Suddenly that bank would not even let them see the bank's front page. After some back and forth on the phone support line it turned out the bank had recently deployed some "advanced" bot detection, one that had a whitelist of residential-ISP-associated AS/IP ranges, and of course whoever compiled and maintained that list had forgot to include that small local ISP. For that regional bank it meant they had just shut out a very significant number of their customers (and potential customers just trying to look up what the bank offers), as there was very likely a huge overlap of people using that regional ISP and that regional bank (both are regional, after all). It also was something they couldn't fix themselves, as the "online banking" stuff was not in-house but was run by the national association (which probably used some bot-detection as a service provider). It took the bank (or rather, the national association) a few weeks to fix. Mind you, the last few years that bank has been heavily marketing a cheaper "online only" account, only online banking, online support, and access to the self-serve ATMs and banking terminals, but no face-to-face or even ear-to-ear human interaction. Try contacting "online support" about "the website outright refuses me" when the "online support" is only available on that website. Kudos is you're smart enough to switch to their mobile app, as your phone uses a different ISP, unless you forget to turn off wifi. That's the advice my parents got from the phone support (they sill have an account type that not online-only).

[1] When I recently visited my parents, from the wifi [same ISP as in 0] I couldn't open the website of a bakery too look up if and when they would be open on a Sunday. Some error message about "this website is not available in your network" (English text, for a German bakery... suspicious :P). I could open it via my mobile, tho. I could open it from my regular ISP when back home (in another city) again. Mind you, that website is purely informational and has no "interactive" features let alone let's you buy anything. It's just static text and some pictures.

Smaller ISPs are also more likely to have issues with CPE getting compromised and routers running botnets within the comfort of your home. There are services which invite people to sell their residential bandwidth in return for money, this can potentially have a disproportionate impact at smaller sample sizes.

Networks can declare themselves to be ISPs. You could check if your ISP shows up as an ISP in peeringDB.

https://networkengineering.stackexchange.com/questions/44585...

They are reportedly very proactive when it comes to CPE security, as well, up to giving customers a proactive phone call when they see somebody is using equipment with known vulnerabilities (customers are allowed to operate their own equipment as long as it is deemed compatible, most will use remotely managed equipment, tho, I believe; my dad used to use his own DSL router and once got such a call if I remember correctly. He switched over to their fiber now and managed equipment).

Their AS is indeed identified as an "ISP" in peeringDB.

While I would be extremely surprised if the company was doing shady things, you surely got a point that a small ISP like that could suffer more in reputation from some few customers being up to shady things, including sub-lending the line. I am pretty sure that is against the ToS, but enforcement is a problem of course. Especially detecting such traffic without violating German privacy laws is probably a difficult task, but it's not impossible.