In the web server on D-Link DIR-620 devices with a certain customized (by ISP) variant of firmware 1.0.3, 1.0.37, 1.3.1, 1.3.3, 1.3.7, 1.4.0, and 2.0.22, there is a hardcoded password of anonymous for the admin account.
D-Link DIR-620 devices, with a certain Rostelekom variant of firmware 1.0.37, have a hardcoded rostel account, which makes it easier for remote attackers to obtain access via a TELNET session.