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eBay is port scanning visitors to their website

blog.nem.ec

101–110 of 148 posts

Re: eBay is port scanning visitors to their website

#102
post #9

I asked this earlier and nobody had a response, so thought I'd ask it again: is there an extension to block this? Edit: @Windows users: pip install pydivert and then try to write a script to block connections from Chrome to non-Chrome processes. you might need GetTcpTable2() or something. (Looking into this now. Check out http://stackoverflow.com/a/25431340 )

uBlock Origin blocks this specific threat (and it's added a few extra filters since this article was posted), however as I noted near the end there are a bunch of other companies running these exact same scans and uBlock only has the ability to block one at a time as they pop up.

I've heard with uMatrix you can block all sites from trying to access localhost/127.0.0.1, which should stop the fingerprinting in its tracks. You may need to enable on a few sites that use localhost for legit things, but those aren't super common.

Re: eBay is port scanning visitors to their website

#103
post #19

This might explain why some preinstalled HP laptop software (with open ports?) causes a BSOD when users visit ebay https://h30434.www3.hp.com/t5/Notebook-Operating-System-and-...

A preinstalled local server, presumably running in kernel space for it cause BSOD, crash when connected from localhost and attempted TLS handshake? The preinstalled crapware never changes.

Re: eBay is port scanning visitors to their website

#104
post #94
post #89

I never understood why websockets aren’t subject to same origin policy and CORS (or similar policies). Any web expert here could explain this design (non-)decision?

Surprisingly often websocket connections are made to a different domain from what is serving the site itself. I'm not sure about the root cause to the pattern, but sure as hell know that our company has been doing it at least since 2013. Browsers set the "Origin" header for ws:// calls, and the websocket servers are expected to check that. Without the check, it'd be possible to issue blind writes (CSRF) from random w…

> Surprisingly often websocket connections are made to a different domain from what is serving the site itself.

That's probably because websockets require asynchronous servers optimizing for number of active connections, while normal sites are best served by servers optimized for response time.

Of course, you can have both handled by the same origin, but it's not the blatantly obvious way.

Re: eBay is port scanning visitors to their website

#105
post #29
post #14

It's crystal clear why they do this. Many companies or persons share their desktops for remote usage. Later they sell this service to eBay users. And they're using it for different fraudulent activities - from making real sales (just for stars) to bidding to own items (for rising price). For years eBay fight this.

It seems like eBay wants it both ways. They want to have a huge user base with low friction to get started, but they also don't want fraudulent players. Instead of doing KYC (know your customer) like many financial services, they're stuck doing dirty tricks like this to try and combat fraud.

Banks also port scan. There was a list in the previous discussion.

Re: eBay is port scanning visitors to their website

#106
post #36

Earlier quoted context omitted.

This is the kind of thing the webkit team at apple raised as privacy problems with webrtc. They got called IE. But seriously, many new specs are very obviously abusable, yet on HN people seem unwilling to accept "this feature is trivially abusable" as a reason to not give developers a new feature, even when it is user hostile. Web specs, and the webdevs he frequently want them, need to consider abusive developers bei…

"IE". Difficult to search for what that means.

Internet Explorer. A much maligned legacy browser for legacy windows desktop platforms.

Aside from being intensely maligned and full of security holes, it doesn't (or didn't?) support WebRTC.

So being called IE is sarcastic like ha ha if you're so concerned about security downgrade to IE which doesn't support WebRTC.

Re: eBay is port scanning visitors to their website

#107

A couple Chrome devtools debugging tips: 1. Local Overrides feature allows you to persist and edit source files across page loads (unfortunately only source files currently, so you're out of luck if the JS comes from an XHR or something) 2. F3 on the network panel will let you search for a string across all resources the page loaded. Can be useful for tracking down where stuff like user-agent checks are called (if no…

Thanks for the tips! Local Overrides is new to me and would have helped a lot. I made heavy use of F3 (also Ctrl+Shift+F) to find my way around those scripts, and to find my place again after each page refresh.

Re: eBay is port scanning visitors to their website

#108
post #29

Earlier quoted context omitted.

It seems like eBay wants it both ways. They want to have a huge user base with low friction to get started, but they also don't want fraudulent players. Instead of doing KYC (know your customer) like many financial services, they're stuck doing dirty tricks like this to try and combat fraud.

Why is it bad to have it both ways?

Because it's at the expense of the customer.

Re: eBay is port scanning visitors to their website

#109
post #82
post #19

This might explain why some preinstalled HP laptop software (with open ports?) causes a BSOD when users visit ebay https://h30434.www3.hp.com/t5/Notebook-Operating-System-and-...

A family member with a Dell has similar BSOD problem when visiting some of these websites. Do we know what software preinstalled on Dell causing the problem?

the BSOD minidump should tell you which driver crashed. GUIs exist for analyzing minidumps, it might even be feasible to talk someone through the process over the phone.

Re: eBay is port scanning visitors to their website

#110
Great article! Finally I got it. Between this one and the original post. 'Why is this website port scanning me'. Can anyone shed some thoughts / reason why the scan is not performed on Linux machines? Maybe not RDP, but VNC servers that the scan performs on Windows m/cs ..
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