Vulnerability assessment and penetration testing both serve important functions for protecting business applications against security threats. The approaches are complementary but should be deployed sequentially. Penetration testing against systems and applications that have not been hardened based on the results of vulnerability assessments is inadvisable since the results are predictable. The objective of penetration testing is to assess the strength of security defenses, not to exploit ill-equipped and unprepared systems and processes to prove a point.
Therefore, vulnerability assessments should be performed ahead of penetration tests. The results of comprehensive vulnerability scans inform organizations of configuration, program, user and other weaknesses that could be exploited to compromise systems during real or simulated attacks. The recommendations resulting from the assessments enable organizations to remediate security weaknesses using a prioritized approach. It also supports the implementation of counter measures to detect and respond to potential attacks.
Once systems are hardened and defenses are prepared, performing a penetration test is a valuable exercise to test the adequacy of security mechanisms. The lessons learned from the discovery and exploitation of vulnerabilities during penetration tests can be applied to address areas that may have been overlooked or inadequately secured after vulnerability assessments. Penetration testing against hardened systems that are actively monitored for attacks forces pen testers to exercise more complex and difficult attack vectors. It also compels pen testers to deploy evasive techniques to avoid detection. This improves the quality of penetration tests and the reliability of the results, providing a stronger litmus test for system security, threat detection and incident response.