[ale] how can a firewalled PC POSSIBLY be attacked?

[Ron Frazier (ALE)]

The discussion on vpn's and security at Emory prompted me to ask this.  This was prompted by some statements in another thread that a PC could be in danger if attached to unfiltered lan ports on Emory's network.

Assume you have a PC connected directly to the internet.  It doesn't matter if it's linux, windows, mac, or android.  I'm speaking in conceptual terms.  Assume the PC is not running any server type programs, so it is not listening on any ports.  Assume no one is browsing to potentially malicious web pages, or even any web pages.  The PC is just sitting there idling.  Assume the PC has firewall software running.  The firewall's only job is to drop all packets that are not part of a response to an inquiry that this PC has issued.    I don't want to debate, at this point, the pros and cons of dropping all packets or operating in stealth mode.

My question is, conceptually speaking, how can this PC POSSIBLY be vulnerable to any remote attack?  How could anything phase it?

Then, how does the answer change depending on whether it is linux, windows, mac, or android.

Finally, if it were behind a hardware firewall, or router, how could any unwanted packets get on the lan?

Sincerely,

Ron


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Ron Frazier
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