Have you ever worried about connecting to Starbuck’s WiFi

Sniffing wireless traffic is shockingly simple if you use anything less than WPA2 to secure your network. It basically involves a client associated with your access point in promiscuous mode. This allows programs like Wireshark to see all packets broadcast on the network – he/she must of course have your wifi decryption keys but WEP is practically insecure to someone with very basic tools. To make such an attack more efficient, the attacker would usually issue an APR (ARP Poison Routing) attack on the network. This involves the attacker announcing that he/she is your router and any data you have bound for the gateway then goes via the attacker. This makes the attacker much more likely to see your data. Once the attacker has created this foundation it is a matter of waiting and watching. A script on the attacker’s machine can check the packets coming through until you do something over HTTP, the unencrypted transfer protocol which will enable sniffing of your cookies and passwords.

Now, the article is actually old but some of them are still true. it not only talks about packet sniffing but also other techniques.

https://www.securityweek.com/how-logging-starbucks-can-compromise-your-corporate-security