The default credentials are:
login: admin
password: admin
But if you use EAP these credentials are turned off by default and there is no active user (security reasons :)). If you want to turn on these users, you have to edit the following file in your current profile: ./deploy/management/console-mgr.sar/web-console.war/WEB-INF/classes/web-console-users.properties. It should be enough to remove the # sign from the line with the user.
If you want to create a new user, don't forget to set up the correct groups in web-console-roles.properties file.
You can easily find information where these information are stored: just open the ./conf/login-config.xml file and find the proper security domain definition. In the case of the Web Console application, it will be web-console policy.
Also if you want to have access to JMX, you have unlock JMX Console. Just check the following files in the conf/props/ directory (in your profile): jmx-console-users.properties and jmx-console-roles.properties.