This paper is the result of various security assessments performed on 
several ZyXEL Prestige devices in both, a controlled environment 
(computer lab) and production environments during several penetration tests.

There are two types of attacks featured in this paper which we believe 
might be potentially new:

- Persistent XSS via SNMP
- Remote wardriving over the Internet


Additionally, the paper is full of other goodies such as:

- Privilege escalation: it allows retrieving administrative settings 
(i.e.: WEP key, ISP and dynamic DNS credentials) and also altering such 
settings

- SNMP read and SNMP *write* access enabled by default: not only we 
demonstrate  how to change settings but we also show how to obtain the 
credentials for the Dynamic DNS service in cleartext

- Poor session management allows hijacking of admin sessions

- Authentication vulnerable to replay and password cracking attacks

- Disclosure of credentials: several types of credentials travel in the 
clear when being submitted by the user, and also when being returned 
from the web interface back to the browser

http://www.procheckup.com/Hacking_ZyXEL_Gateways.pdf