the-web-application-hackers-handbook

Chapter 2 n Core Defense Mechanisms 31
by presenting an uninformative error message. See Chapter 15 for more details
on these measures.
Figure 2-6: An unhandled error
Effective error handling is often integrated with the application’s logging
mechanisms, which record as much debug information as possible about unanticipated
errors. Unexpected errors often point to defects within the application’s
defenses that can be addressed at the source if the application’s owner has the
required information.
Maintaining Audit Logs
Audit logs are valuable primarily when investigating intrusion attempts against
an application. Following such an incident, effective audit logs should enable
the application’s owners to understand exactly what has taken place, which
vulnerabilities (if any) were exploited, whether the attacker gained unauthorized
access to data or performed any unauthorized actions, and, as far as possible,
provide evidence of the intruder’s identity.