-O is a command-line switch used for OS detection in Nmap.
For example, nmap -O 192.168.1.1.

Script kiddies are hackers who are new to hacking and don’t have much knowledge or skills to perform hacks. Instead, they use tools and scripts developed by more experienced hackers.

XOR (eXclusive OR) is a boolean logic operation that is widely used in cryptography. It is used in generating parity bits for error checking and fault tolerance. The output is True (or 1) if and only if the two inputs are different. The output is false (or 0) if the two inputs have the same value.

A collision attack is an attempt to find two input strings of a hash function that produce the same hash result.

In a Smurf attack, a large amount of ICMP echo request (ping) traffic is sent to an IP broadcast address, with a spoofed source IP address of the intended victim. IRC servers are commonly used to prolong thus making them the primary victim of this attack.

Maltego is an open-source intelligence and forensics software application developed by Paterva. It is a comprehensive tool for graphical link analysis that offers real-time data mining and information gathering which can be presented in a graph format.

To open the Computer Management Console from the command line just type compmgmt.msc in your run box or at the command line.

Ransomware is a form of malware that restricts the user from accessing their infected computer system or files and then asks for a ransom payment to regain user access. The main goal of a ransomware attack is to extort money from its victims.

A rainbow table attack is a hacking method that involves the use of a rainbow hash table. This table contains the values used to encrypt the passwords before adding them to the database.

HTTP-methods returns all the available methods on the server.

Active sniffing involves sending out multiple network probes to identify access points. The following are examples of different active sniffing techniques: • MAC flooding • DNS poisoning • ARP poisoning • DHCP attacks • Switch port stealing • Spoofing attack

In an asymmetric key system, public keys are shared or available to anyone, while private keys are held only by the key owner.

Vulnerability scanning is a method used in checking whether a system is exploitable or not by identifying its vulnerabilities.

With rule-based access control, when a request is made for access to a network or network resource, the controlling device, e.g. firewall, checks properties of the request against a set of rules. A rule might be to block an IP address or a range of IP addresses.

You must report your client immediately if they are involved in any illegal activities.

OS fingerprinting is the process a hacker goes through to determine the type of operating system being used on a targeted computer. This is beneficial because it gives the hacker useful information about any security vulnerabilities of the operating system that can be exploited to launch an attack.

Polymorphic shellcode encrypts the shellcode by XORing values over the shellcode, using loader code to decrypt the shellcode, and then executing the decrypted shellcode.

Suicide hackers are those who hack for some purpose and even don’t bother to suffer long-term jail due to their activities.

A black-box tester is unaware of the internal structure of the application to be tested, while a white-box tester has access to the internal structure of the application. A gray-box tester partially knows the internal structure, which includes access to the documentation of internal data structures as well as the algorithms used.

RSA is based on the practical difficulty of factoring the product of two large prime numbers, the factoring problem.

Open Web Application Security Project or OWASP is a non-profit organization dedicated to providing unbiased, practical, and cost-effective information about application security. OWASP’s Top 10 Security Vulnerabilities provides a ranking of the top ten most prevalent security vulnerabilities which also serves as a guideline for developers and security professionals.

Nmap or network mapper is a powerful reconnaissance tool. It is a free, open-source Linux command-line tool that can be used to gather lots of information about the target. This program can be used in finding active hosts on a network, perform port scanning, ping sweeps, and, OS and version detection.

A worm is a type of malware that replicates, executes, and spreads across network connections, but unlike a computer virus, it does not need the help of human interaction. It is designed to consume all available computing resources causing network, web, and individual computer systems to become overloaded and stop responding.

Network Time Protocol (NTP) is a protocol used to synchronize computer clock times in a network.

Cavity virus known as spacefiller virus is a rare type of computer virus that installs itself by filling in empty sections of a file. By only using empty sections of a file, the virus can infect a file without the size of the file changing, making it more difficult to detect.

In cryptography, Triple DES (3DES or TDES), officially the Triple Data Encryption Algorithm (TDEA or Triple DEA), is a symmetric-key block cipher, which applies the DES cipher algorithm three times to each data block.

-sS = Stealth scanning
-O = Operating System (OS) checking
-p = Scan fewer ports
-p 150 to 160 = Scanning ports 150 to 160

General Data Protection Regulation or GDPR is a regulation that requires businesses to ensure the protection of personal data and privacy of European citizens. It establishes one law across the continent and a single set of rules which applies to companies doing business within EU member states.

Dynamic ARP inspection (DAI) is a security feature that rejects invalid and malicious ARP packets. The feature prevents a class of man-in-the-middle attacks, where an unfriendly station intercepts traffic for other stations by poisoning the ARP caches of its unsuspecting neighbors.

The fourth phase of ethical hacking is maintaining access. In this phase, the hacker will secure his or her access to the system to maintain it for a longer time for future exploitation and additional attack purposes. To keep the access and maintain undetected for a longer time, the hacker must remain invisible to the host system to avoid getting caught.

An audit trail is a step-by-step record by which accounting or trade data can be traced to its source.

Worms are designed to consume all available computing resources causing network, web, and individual computer systems to become overloaded and stop responding. Some popular examples are Stuxnet, Morris worm, and Code red worm.

Hacktivists break into government agencies or big corporate systems out of protest. They use their skills to promote a political or social agenda.

Vulnerability scanning is a method used to check whether a system is exploitable by identifying its vulnerabilities. A vulnerability scanner consists of a scanning engine and a catalog. These tools generally target vulnerabilities that secure host configurations can fix easily, updated security patches, and a clean Web document.

The so-called Connection String Parameter Pollution (CSPP) attack exploits poorly secured dynamic connections between Web apps and databases, namely ones that still use semicolons as separators between data such as the data source, user ID, and password associated with a connection to the database, for instance.

Dumpster diving (or searching for useful information through a potential victim’s garbage dump). This is an often-used method of social engineering. In the corporate world, a lot of valuable data, such as employees’ names, phone numbers, organizational charts, as well as user credentials and passwords written in notes, can be found in the company’s trash.

In an asymmetric key system, public keys are shared or available to anyone, while private keys are held only by the key owner.

Network TAPs are a purpose-built hardware device that sits in a network segment, between two appliances (router, switch or firewall), and allows you to access and monitor the network traffic.