When logging a message there are several important requirements which must be fulfilled:

• The user must be able to easily retrieve the logs
• The format of all logged message must be uniform to allow the user to easily read the log
• Logged data must actually be recorded
• Sensitive data must only be logged securely

If a program directly writes to the standard outputs, there is absolutely no way to comply with those requirements. That’s why defining and using a dedicated logger is highly recommended.

Noncompliant Code Example

private void DoSomething()
{
    // ...
    Console.WriteLine("so far, so good..."); // Noncompliant
    // ...
}

Exceptions

The following are ignored by this rule:

• Console Applications
• Calls in methods decorated with [Conditional ("DEBUG")]
• Calls included in DEBUG preprocessor branches (#if DEBUG)

See

• OWASP Top 10 2021 Category A9 - Security Logging and Monitoring Failures