This link deals with modem security problems. (It's followed by an article which should interest Tor users.)
http://www.tomsguide.com/us/home-router-security,news-19245.html

From the article:

Most gateway routers used by home customers are profoundly not secure, and some routers are so vulnerable to attack that they should be thrown out, a security expert said at the HOPE X hacker conference in New York...

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"We have met the enemy and he is us." -- Pogo
Greetings from coastal Washington state, the scenic US Pacific Northwest.

Interestingly, I have a router/modem from my isp and it isn't full of the security holes listed.

Surprisingly it doesn't mention the simple security measure of turning off the modem when computers are not in use.