Explanation: Penetration testing (also called pen testing) is the practice of testing a computer system, network, or Web application to find vulnerabilities that an attacker could exploit. Following are the areas that can be exploited in a penetration test: Kernel flaws: Kernel flaws refer to the exploitation of kernel code flaws in the operating system. Buffer overflows: Buffer overflows refer to the exploitation of a software failure to properly check for the length of input data. This overflow can cause malicious behavior on the system. Race conditions: A race condition is a situation in which an attacker can gain access to a system as a privileged user. File and directory permissions: In this area, an attacker exploits weak permissions restrictions to gain unauthorized access of documents. Trojan horses: These are malicious programs that can exploit an information system by attaching themselves in valid programs and files. Social engineering: In this technique, an attacker uses his social skills and persuasion to acquire valuable information that can be used to conduct an attack against a system.