# Introduction

## The Information Security Field

> ⚡ Penetration Testing Usage:
>
> * Knowing the information security (**`infosec`**) field
> * Career opportunities
> * Talking with colleagues

### InfoSec Culture

Deep roots in the underground hacking scene.

**`Hacker`** = refers to people who prefer to understand how a system works, being curious, intelligent and motivated to pursue knowledge.

Usually a hacker approaches systems with curiosity, so he can:

* Find new ways to use computer systems
* Bypass imposed restrictions
* Understand security pitfalls

*Performing an attack* means to **understand** the technology and the functioning of the target system.

*Being a Hacker* means **improving** skills every day, pushed by **curiosity** and hunger for **knowledge**.

> 📕 There is always something new to learn! *Hacking* is a lifestyle.

*Being an InfoSec professional* means pursuing knowledge by keeping challenging yourself and your colleagues, being honest with yourself and never stop.

* To have an idea about the ideals of the underground hacking community read [The Conscience of a Hacker](http://phrack.org/issues/7/3.html).

![](https://1996978447-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FlhjuckuLbvBn36EoFL7P%2Fuploads%2Fgit-blob-c5bb1d4a8d551fb5dbcfdd6964c405d989ae8fd6%2FTheConscienceOfAHacker_TheMentor_pic.png?alt=media)

### Career Opportunities

Companies and government bodies are using advanced tech to store and process confidential data. Using hacking skills for good has become critical for the safety of nations too.

*Data is transmitted* across private & public networks. It is a **must** to:

* **Protect sensitive information**
* Implement hardware and software defensive systems
* Protect `digital assets` from major **cyber-threats** like:
  * global cyber syndicates
  * hackers for hire
  * hacktivists
  * terrorists
  * state-sponsored hackers

*Train the organization* to make sure:

* secure applications are developed
* proper defensive measures are taken
* proper use of the company's data is in place

*Hire a penetration tester* to ensure that a system is secure from cyber-attacks.

**`Penetration Testers`** (a.k.a. **`pentesters`**) = are professionals hired to simulate a hacking attack against a network, a computer system, a web application or the entire organization. They discover vulnerabilities across the tested systems by mastering the same tools and techniques used by malicious hackers. They often work:

* as freelancers
* in an IT Security services company
* as in-house employees

Pentesters can specialize in specific InfoSec sectors:

* Systems attacks
* Web Applications
* Malware Analysis
* Reverse Engineering
* Mobile Applications
* Network Pentesting
* Social Engineering
* Other...

> 📌 Be passionate, skilled and hungry for knowledge!

***

### Information Security Terms

It is fundamental to speak the InfoSec domain language.

***

**`WHITE HAT HACKER`**

* is a professional pentester or ***ethical hacker*** who performs *authorized* attacks against a system helping the client *solve* their security issues.
* they do NOT perform illegal actions.

***

**`BLACK HAT HACKER`**

* is a hacker who performs *unauthorized* attacks against a system with the purpose of *causing damage* or gaining *profit*.
* a category of black hat hackers is called "*crackers*".

***

**`USER`**

* is a computer system user (an employee of your client of an external user).

***

**`MALICIOUS USER`**

* is a user who *misuses* or *attacks* computer systems and applications.

***

**`ROOT / ADMINISTRATOR`**

* are the users who manage IT networks or single systems.
* they have *maximum privileges* over a system.

***

**`PRIVILEGES`**

* identify the action that a user is *allowed* to do.
* the higher the privileges, the more control.

***

**`SECURITY THROUGH OBSCURITY`**

* is the use of *secrecy of design*, implementation or configuration in order to provide security.
* it *cannot stop* a skilled and motivated attacker.

***

**`ATTACK`**

* is any kind of action aimed at *misusing* or *taking control* over a computer system or application.
  * unauthorized access to an administration area
  * stealing a user's credentials
  * causing denial of service
  * eavesdropping or communications

***

**`PRIVILEGE ESCALATION`**

* **`privesc`** is an attack where a malicious user *gains elevated privileges* over a system.

***

**`DENIAL OF SERVICE`**

* a **`DoS attack`** is used by an attacker to make a system or a service unavailable / unresponsive, causing a service crash or resources saturation.

***

**`REMOTE CODE EXECUTION`**

* during a **`RCE attack`** a malicious user executes some attacker-controlled *code* on a victim *remote* machine.
* RCE vulnerabilities can be *exploited* over the network by a remote attacker.

***

**`SHELL CODE`**

* is a piece of custom code which provides the attacker a **`shell`** on the victim machine, generally used during RCE attacks.

***

## Cryptography Protocols & VPNs

> ⚡ P.T. Usage:
>
> * Knowing how info is transmitted over networks, by using the right protocol for the transmission
> * Traffic protection

### Clear-text Protocols

* They should **not** be used for the transmission of critical or private info, since it's easy to intercept.
* Use clear-text protocols only on trusted networks, if really necessary.

### Cryptographic Protocols

* They are used to protect the communication by *encrypting* the transmitted information, in case of eavesdropping.
* Always use a **cryptographic** protocol for usernames and passwords.

A Clear-text protocol information can be wrapped into a cryptographic protocol, like a *VPN tunnel*.

### Virtual Private Networks (VPN)

A **`VPN`** establish a secure, encrypted and protected connection between a private network and a public one (or the Internet), using a private tunnel for the data.

* The client is directly connected to the private network.

***

## Wireshark

* **`Wireshark`** is a network sniffer tool and packet analyzer, that allows to capture the data transmitted over the network.

> 🔬 Check [*HTTP(s) Traffic Sniffing*](https://blog.syselement.com/ine/courses/ejpt/exam-preparation-labs/p.t.-prerequisites-labs/http-s-traffic-sniffing) lab.

***

## Binary Arithmetic Basics

> ⚡ P.T. Usage:
>
> * Computer/Boolean logic, data is represented in binary format
> * Network addressing

### Binary and Decimal Bases

**`Binary`** notation uses only two symbols to represent numbers, **0** (**zero**) and **1** (**one**).

**`Decimal`** notation uses ten symbols (0 to 9).

* *Counting* in binary: start counting from 0, when reach 1, you increment the digit to the left of it.
  * 0, 1, 10, 11, 100, 101, 110, 111, 1000 ... and so on.
* *Converting* from **bin**ary to **dec**imal: by using the position of the digits.

  $$
  11011(*2) = 1*2^0+1*2^1+0*2^2+1*2^3+1\*2^4=27*{(10)}
  $$
* *Converting* from **dec**imal to **bin**ary:

  * by dividing the decimal number by 2 (base 2), write the remainder, continue like this until reaching 0 as dividend.

  $$
  26/2=13 \remainder\ is\ 0 \ 13/2=6 \remainder\ is\ 1 \ 6/2=3 \remainder\ is\ 0 \ 3/2=1 \remainder\ is\ 1 \ 1/2=0 \remainder\ is\ 1 \\
  $$

  $$
  26\_{(10)}=11010(\_2)
  $$

  * Or use the powers of two in a "base 2 table":

  $$
  {Powers\ of\ 2} \ 2^0=1 \ 2^1=2 \ 2^2=4 \ 2^3=8 \ 2^4=16 \ 2^5=32 \ 2^6=64 \ 2^7=128 \ 2^8=256 \ 2^9=512 \ 2^{10}=1024 \ 2^{11}=2048 \ 2^{12}=4096 \ 2^{13}=8192 \ 2^{14}=16384 \ 2^{15}=32768
  $$

  $$
  {Example\ } \ 2^4+2^3+2^1=16+8+2=26 \ 2^4\ YES\ \dashrightarrow 1 \ 2^3\ YES\ \dashrightarrow 1 \ 2^2\ NO\ \dashrightarrow 0 \ 2^1\ YES\ \dashrightarrow 1 \ 2^0\ NO\ \dashrightarrow 0 \ 26\_{(10)}=11010(\_2)
  $$

### Bitwise operations

* **`NOT`** flips the bits - zero to one, and one to zero.

  $$
  NOT(11011)=00100
  $$
* **`AND`** logical AND (**&**) between the bits of the operands.

  $$
  {If\ both\ bits\ are\ =1, result\ is\ 1.} \ 0\ &\ 0\ = 0 \ 0\ &\ 1\ = 0 \ 1\ &\ 0\ = 0 \ 1\ &\ 1\ = 1
  $$

  $$
  1010\ &\ 1101\ = 1000
  $$
* **`OR`** logical OR (**|**) between the bits of the operands.

  $$
  {If\ at\ least\ one\ bit\ is\ =1, result\ is\ 1.} \ 0\ |\ 0\ = 0 \ 0\ |\ 1\ = 1 \ 1\ |\ 0\ = 1 \ 1\ |\ 1\ = 1
  $$

  $$
  1010\ |\ 1100\ = 1110
  $$
* **`XOR`** logical Exclusive OR (**^** , **⊕**) between the bits of the operands.

  $$
  {If\ just\ one\ bit\ is\ =1, result\ is\ 1.} \ 0 \oplus 0\ = 0 \ 0 \oplus 1\ = 1 \ 1 \oplus 0\ = 1 \ 1 \oplus 1\ = 0
  $$

  $$
  1010 \oplus 1101\ = 0111 = 111
  $$

Windows calculator can help with calculations in "Programmer" mode.

![](https://1996978447-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FlhjuckuLbvBn36EoFL7P%2Fuploads%2Fgit-blob-1b89d9e6976e932013a4f72f3f2ab4ddd32db809%2Fimage-20220131231201595.png?alt=media)

### Hexadecimal arithmetic

**`Hexadecimal`** system is used too in computer science. It uses 16 symbols (with letters for double-digit numbers):

* `0, 1, 2, 3, 4, 5, 6, 7, 8, 9, A, B, C, D, E, F`

To distinguish a hexadecimal number from a decimal number, "**0x**" at the beginning or "**h**" at the end is added.

* *Converting* from **hex**adecimal to **dec**imal: by using the position of the digits.

  $$
  0x4a1 = 0x(4\ 10\ 1) \ 0x4a1 = 1*16^0 + 10*16^1 + 4\*16^2 = 1 + 160 + 1024 = 1185\_{(10)}
  $$
* *Converting* from **dec**imal to **hex**adecimal:

  * by subsequently dividing the decimal number by 16 (base 16), write the remainder, continue like this until reaching 0.

  $$
  1185/16=74,0625 \remainder\ is\ 0,0625 \ 74/16=4,625 \remainder\ is\ 0,625 \ 4/16=0,25 \remainder\ is\ 0,25 \ 0/16=can't\ divide\ 0.
  $$

  $$
  0.25*16=4 \ 0.625*16=10\ (a) \ 0.0625\*16=1
  $$

  $$
  1185\_{(10)}=4a1\_{(16)}=0x4a1
  $$

> 📌Online converters can help to speed up the calculations, for example here you can find some conversion tools [Binary Hex Converters](https://www.binaryhexconverter.com/).

***