Scanning the LAN through your browser is nothing new. JS-Recon from AnD Labs [0] is a tool from 2010 that could do it. I have seen eBay [1], Facebook [2], and H

Scanning the LAN through your browser is nothing new. JS-Recon from AnD Labs [0] is a tool from 2010 that could do it. I have seen eBay [1], Facebook [2], and Halifax [3] do it too, albeit for other reasons than scanning for outdated devices (fraud/loss prevention). LexisNexis' ThreatMetrix [4] is commonly used to do this. Please note that this is a copy of a comment I made 2 years ago and I have not tested the links to see if they are still correct. [0]: https://web.archive.org/web/20101128053633/http://www.andlabs.org:80/tools/jsrecon/jsrecon.html https://web.archive.org/web/20101128053633/http://www.andlab... [1]: https://forum.ultravnc.net/viewtopic.php?f=7&t=33509 https://forum.ultravnc.net/viewtopic.php?f=7&t=33509 [2]: https://www.reddit.com/r/AskNetsec/comments/4j0nas/why_is_facebook_checking_my_open_ports/ https://www.reddit.com/r/AskNetsec/comments/4j0nas/why_is_fa... [3]: https://www.theregister.com/2018/08/07/halifax_bank_ports_scans/ https://www.theregister.com/2018/08/07/halifax_bank_ports_sc... [4]: https://risk.lexisnexis.com/products/threatmetrix https://risk.lexisnexis.com/products/threatmetrix