How can an attacker eavesdrop on users in public WIFI?

Question

I want know why it's said that public WIFI is not safe for banking transactions or entering password for online accounts etc. I want to imitate an attacker and try to harvest as much information as I can from my local wireless network in my home with a couple users. I have a background on working with hacking tools included in Kali linux or Owasp on Microsoft Windows.

In order to imitate a controlled attack and to know how much information can be gathered and how it's done, I'm looking for a way to sniff in my local network and find out what data other devices are transmitting over the network, like passwords, keywords transmitted over the network (HTTP and if possible also HTTPS websites). these are the things that come to my mind when I think about an unsafe public WIFI and what nefarious things an attacker can do to obtain data.

I have a second question regarding this, because I have access to my home wireless router, can I setup a local DNS server on my Windows or Linux (VM) and it work as a relay DNS server (i.e doesn't contain any DNS data, only be used to direct the data being transmitted over the network to my computer so that I can see the data) ? is it possible, and if yes then please point to the right direction and how can it be done. if not, please explain why and what other options do I have for my purpose? or what an attacker with enough motication actually would do in a situation like this?

Answer 1

When accessing a public wifi an attacker might use applications such as wire shark to capture packet information (the data of users), if encrypted the attacker will most likely attempt some kind of MitM

MitM ARP poison, this will essentially tell the victims machine "Yo, Im the next hop I swear". with this the traffic could be directed through the attackers machine.

how would the attacker deal with this? well thats tricky because an attacker could either redirect all 443 traffic to 80 but alot of websites patched that common easy problem years ago.

The attacker could DNS steal and send the user to his own custom webpage (which could be a spoof of a common website and it would appear ligit)

being within a network as well gives you in depth sight to those on a network and their activity, some times people even broadcast their files to the world. Also not just this but you can also try more attacks out which firewalls may be strengthen from.

There are many more possibilities of what an attacker could do but this is a few points!