== Password Erasure

After successful authentication, it is a security best practice to erase credentials from memory to prevent them from being exposed to potential memory dump attacks.
`ProviderManager` in Spring Security supports this practice through the `eraseCredentials` method, which should be invoked after the authentication process is complete.

=== Best Practices

* *Immediate Erasure*: Credentials should be erased immediately after they are no longer needed, which minimizes the window during which the credentials are exposed in memory.
* *Automatic Erasure*: Configure `ProviderManager` to automatically erase credentials post-authentication by setting `eraseCredentialsAfterAuthentication` to `true` (the default).
* *Custom Erasure Strategies*: Implement custom erasure strategies in custom `AuthenticationManager` implementations if the default erasure behavior does not meet specific security requirements.

=== Risk Assessment

Failure to properly erase credentials can lead to several risks:

* *Memory Access Attacks*: Attackers can access raw credentials from memory through exploits like buffer overflow attacks or memory dumps.
* *Insider Threats*: Malicious insiders with access to systems could potentially extract credentials from application memory.
* *Accidental Exposure*: In multi-tenant environments, lingering credentials in memory could accidentally be exposed to other tenants.

=== Implementation

[source,java]
----
public class CustomAuthenticationManager implements AuthenticationManager {

	@Override
	public Authentication authenticate(Authentication authenticationRequest)
			throws AuthenticationException {

		Authentication authenticationResult;
		// TODO: Perform authentication checks...

		// Erase credentials post-check
		if (authenticationResult instanceof CredentialsContainer container) {
			container.eraseCredentials();
		}
	}

}
----

By implementing these practices, organizations can significantly enhance the security of their authentication systems by ensuring that credentials are not left exposed in system memory.
