ZyXEL Prestige routers, including P-660 and P-661 models with firmware 3.40(AGD.2) through 3.40(AHQ.3), have (1) "user" as their default password for the "user" account and (2) "1234" as their default password for the "admin" account, which makes it easier for remote attackers to obtain access.
ZyXEL Prestige routers, including P-660, P-661, and P-662 models with firmware 3.40(AGD.2) through 3.40(AHQ.3), allow remote authenticated users to obtain ISP and Dynamic DNS credentials by sending a direct request for (1) WAN.html, (2) wzPPPOE.html, and (3) rpDyDNS.html, and then reading the HTML source.
The SNMP service on ZyXEL Prestige routers, including P-660 and P-661 models with firmware 3.40(AGD.2) through 3.40(AHQ.3), has "public" as its default community for both (1) read and (2) write operations, which allows remote attackers to perform administrative actions via SNMP, as demonstrated by reading the Dynamic DNS service password or inserting an XSS sequence into the system.sysName.0 variable, which is displayed on the System Status page.
The default SNMP configuration on ZyXEL Prestige routers, including P-660 and P-661 models with firmware 3.40(AGD.2) through 3.40(AHQ.3), has a Trusted Host value of 0.0.0.0, which allows remote attackers to send SNMP requests from any source IP address.
ZyXEL Prestige routers, including P-660, P-661, and P-662 models with firmware 3.40(PE9) and 3.40(AGD.2) through 3.40(AHQ.3), do not use a salt when calculating an MD5 password hash, which makes it easier for attackers to crack passwords.
ZyXEL Prestige routers, including P-660, P-661, and P-662 models with firmware 3.40(PE9) and 3.40(AGD.2) through 3.40(AHQ.3), support authentication over HTTP via a hash string in the hiddenPassword field, which allows remote attackers to obtain access via a replay attack.
ZyXEL Prestige routers, including P-660, P-661, and P-662 models with firmware 3.40(AGD.2) through 3.40(AHQ.3), allow remote authenticated users to obtain authentication data by making direct HTTP requests and then reading the HTML source, as demonstrated by a request for (1) RemMagSNMP.html, which discloses SNMP communities; or (2) WLAN.html, which discloses WEP keys.
ZyXEL Prestige routers have a minimum password length for the admin account that is too small, which makes it easier for remote attackers to guess passwords via brute force methods.
ZyXEL ZyWALL 1050 has a hard-coded password for the Quagga and Zebra processes that is not changed when it is set by a user, which allows remote attackers to gain privileges.
Multiple cross-site request forgery (CSRF) vulnerabilities on the ZyXEL P-660HW series router allow remote attackers to (1) change DNS servers and (2) add keywords to the "bannedlist" via unspecified vectors.