What Do Ethical Hackers Do?

Ethical hackers are motivated by different reasons, but their purpose is usually the same as that of crackers: they're trying to determine what an intruder can see on a targeted network or system, and what the hacker can do with that information. This process of testing the security of a system or network is known as a penetration test, or pen test.

Hackers break into computer systems. Contrary to widespread myth, doing this doesn't usually involve a mysterious leap of hackerly brilliance, but rather persistence and the dogged repetition of a handful of fairly well-known tricks that exploit common weaknesses in the security of target systems. A pen test is no more than just performing those same steps with the same tools used by a malicious hacker to see what data could be exposed using hacking tools and techniques.

Many ethical hackers detect malicious hacker activity as part of the security team of an organization tasked with defending against malicious hacking activity. When hired, an ethical hacker asks the organization what is to be protected, from whom, and what resources the company is willing to expend in order to gain protection. A penetration test plan can then be built around the data that needs to be protected and potential risks.

Documenting the results of various tests is critical in producing the end product of the pen test: the pen test report. Taking screenshots of potentially valuable information or saving log files is critical to presenting the findings to a client in a pen test report. The pen test report is a compilation of all the potential risks in a computer or system. 

Goals Attackers Try to Achieve

Whether perpetuated by an ethical hacker or malicious hacker, all attacks are an attempt to breach computer system security. Security consists of four basic elements:

• Confidentiality
• Authenticity
• Integrity
• Availability

A hacker's goal is to exploit vulnerabilities in a system or network to find a weakness in one or more of the four elements of security. For example, in performing a denial-of-service (DoS) attack, a hacker attacks the availability elements of systems and networks. Although a DoS attack can take many forms, the main purpose is to use up system resources or bandwidth. A flood of incoming messages to the target system essentially forces it to shut down, thereby denying service to legitimate users of the system. Although the media focuses on the target of DoS attacks, in reality such attacks have many victims—the final target and the systems the intruder controls.

Information theft, such as stealing passwords or other data as it travels in cleartext across trusted networks, is a confidentiality attack, because it allows someone other than the intended recipient to gain access to the data. This theft isn't limited to data on network servers. Laptops, disks, and backup tapes are all at risk. These company-owned devices are loaded with confidential information and can give a hacker information about the security measures in place at an organization.

Bit-flipping attacks are considered integrity attacks because the data may have been tampered with in transit or at rest on computer systems; therefore, system administrators are unable to verify the data is as the sender intended it. A bit-flipping attack is an attack on a cryptographic cipher: the attacker changes the cipher text in such a way as to result in a predictable change of the plain text, although the attacker doesn't learn the plain text itself. This type of attack isn't directed against the cipher but against a message or series of messages. In the extreme, this can become a DoS attack against all messages on a particular channel using that cipher. The attack is especially dangerous when the attacker knows the format of the message. When a bit-flipping attack is applied to digital signatures, the attacker may be able to change a promissory note stating "I owe you $10.00" into one stating "I owe you $10,000."

MAC address spoofing is an authentication attack because it allows an unauthorized device to connect to the network when Media Access Control (MAC) filtering is in place, such as on a wireless network. By spoofing the MAC address of a legitimate wireless station, an intruder can take on that station's identity and use the network.