JavaScript : Internal information leak

System configuration information leak is possible. This can help an attacker to plan an attack.

Debug information and error messages can be written to the log, displayed to the console, or sent to the user depending on the system settings. In some cases, an attacker can make a conclusion about the system vulnerabilities from the error message. For example, a database error can indicate insecurity against SQL injection attacks. Information about the version of the operating system, application server and system configuration can also be of value to the attacker.

In this case, we are talking about an internal leak: system information is stored in the local file or event log or is displayed on the screen.

This applies both to the classic web applications and mobile applications.