I have a various devices on my LAN network (Linux, Windows, Android device..), sometimes i allow others to connect to my LAN through , it is not possible to verify the safety of their machines, Let's say i have allowed an in-trusted machine to connect trough my router. How can the infected device harm others machines?
there are lots of attack vectors, such as :
- Sniffing admin/user passwords and exploiting systems using them
- Accessing an anonymous shares and planting malware there(if they're not read-only)
- Performing MitM attacks to steal data
- Exploiting IPv6 in LAN : it's often an IPv4 LAN's but people forget to disable IPv6, so it's a prioritized by OS, especially Windows, and sending a router announcement makes you a LAN owner(I performed it myself, it works)
- Stealing Kerberos tickes
... and too many other ways to mention them all