Hey guys! Ready to dive into the world of cybersecurity with a fun and engaging challenge? We're talking about the Advent of Cyber 2020 event on TryHackMe, a fantastic platform for learning and practicing ethical hacking. This walkthrough will break down the challenges, offering insights and solutions to help you level up your cybersecurity skills. So, grab your virtual keyboard, and let's get started!

Day 1: Hello World - Introduction to Web Exploitation

Alright, let's kick things off with Day 1! The first day often serves as an introduction or a warm-up, and this one's no different. It's designed to introduce you to the basics of web exploitation. You will get to understand how websites work and how to interact with them in ways that the developers may not have intended. Key concepts covered here usually include HTTP requests, HTML structure, and some simple vulnerabilities, setting the stage for more complex challenges ahead. Understanding the building blocks of web applications is super important, so pay close attention!

In this particular challenge, you're likely introduced to a vulnerable web application, maybe one with a simple form or a basic interface. The goal is to interact with the application. To tackle this, you'll need to understand how web browsers communicate with web servers. This communication happens using Hypertext Transfer Protocol (HTTP). HTTP is a request-response protocol. Your browser (the client) sends a request to a server, and the server sends back a response. You can think of the HTTP request as a note you pass to the server, and the response is the note the server writes back to you. Common requests are GET (used to retrieve information) and POST (used to send data to the server). HTML provides the structure of the web page. Think of HTML as the skeleton of the website. It uses tags to define elements like headings, paragraphs, images, and links. Knowing basic HTML tags can help you understand the layout of a web page and sometimes even reveal hidden vulnerabilities. You might need to examine the source code of the webpage, which is the underlying HTML, CSS, and JavaScript that makes the webpage function. Web browsers let you view the source code. You'll likely need to use your browser's developer tools. These tools are your best friend! They allow you to inspect elements, view network requests, and debug any issues you find. Look for the 'Inspect' or 'Developer Tools' option in your browser menu. If there's an input field, try things. Always try to break the system. Enter different inputs to see what happens. This can include different types of input, like text, numbers, or even special characters. Check for common vulnerabilities such as cross-site scripting (XSS). This involves injecting malicious scripts into the web application. When other users view the page, their browsers will execute the script, which can result in the theft of cookies or other sensitive information.

Day 2: Decoding the Message - Cryptography Basics

Day 2 takes you down the path of cryptography, which is the art of secure communication. You'll be introduced to the fundamental concepts and techniques used to protect information from prying eyes. This day typically covers topics like encryption, decryption, and basic ciphers. Don't worry, it's not as scary as it sounds. It's all about understanding how to encode and decode messages to keep them secret! The core idea behind cryptography is to transform information (plaintext) into an unreadable format (ciphertext) using a secret key. This process is called encryption. The reverse process, converting ciphertext back into plaintext, is called decryption and requires the same or a related key. You will be introduced to classic ciphers like Caesar Cipher. This is one of the simplest ciphers. Each letter in the plaintext is replaced by a letter some fixed number of positions down the alphabet. For instance, with a shift of 3, A would be replaced by D, B would become E, and so on. You'll learn to identify and break it. Another one is the Substitution Cipher. This cipher involves replacing each letter in the plaintext with a different letter or symbol based on a specific key. Each letter is substituted for another. Frequency analysis will become your best friend. This is a technique used to break substitution ciphers. It involves analyzing the frequency of letters in the ciphertext. Because different languages have different letter frequency distributions. For instance, in English, the letter 'E' is the most frequent. You can use this knowledge to help you to guess which letters in the ciphertext map to which letters in the plaintext.

Make sure to familiarize yourself with the tools of the trade. You'll use online decrypters, cipher tools, and maybe even write some basic scripts to automate the decryption process. Start by identifying the cipher. This will depend on the clues in the challenge. Then, based on the cipher type, you can attempt to reverse the process using online tools or manual techniques. Remember, practice makes perfect. The more you work with different ciphers, the better you'll become at recognizing patterns and breaking codes!

Day 3: File System Fundamentals and Exploration

On Day 3, it's time to get your hands dirty with file systems. This is your chance to learn how data is organized and stored on a computer, and how to navigate around to find hidden gems. This day usually focuses on common file system structures, how to locate and read files, and maybe a bit of steganography (the art of hiding messages within other files). Understanding the layout of a file system is essential for any cybersecurity professional. File systems organize files and directories in a hierarchical structure. This structure helps you understand where different files are located. Common file system structures include the root directory, which is the top-level directory, and subdirectories and files. Familiarize yourself with basic Linux commands. You'll probably be working with a Linux environment. Knowing commands like ls (list files), cd (change directory), pwd (print working directory), and cat (concatenate and print files) is super essential. Learning to explore files is an important skill. The challenge will probably involve finding and reading specific files. Use the ls command to list the contents of a directory, then use cd to navigate into different directories. Once you've located a file you want to read, use the cat command to display its contents on the console. Steganography is the art of concealing a file, message, image, or video within another file, message, image, or video. The goal is to hide the secret from detection. You might have to investigate images, audio files, or other media files. You'll have to use tools to extract hidden information. This could involve looking at metadata (information about the file) or using specialized tools to extract hidden messages or files. Be sure to check the file's metadata, such as the creation date, author, or other hidden details, which can provide clues. Use steganography tools to extract hidden messages. There are tons of online and offline tools like Steghide and Stegsolve. Use them to extract hidden data from images or other files.

Day 4: Intro to Networking and Packet Analysis

Day 4 takes you into the world of networking and packet analysis. This is a crucial area of cybersecurity, as it deals with how data moves across networks. You'll learn the basics of network protocols, how to capture network traffic, and how to analyze packets to uncover valuable information. Get ready to put on your detective hat and solve some network mysteries! You will be introduced to the basics of network protocols. These are the rules that govern how data is transmitted over a network. Common protocols include the Transmission Control Protocol/Internet Protocol (TCP/IP), Hypertext Transfer Protocol (HTTP), and Domain Name System (DNS). Learning about these protocols will help you understand how data is structured and how it flows across the network. Understanding how packets work is very important. All data sent over a network is broken down into small units called packets. Each packet contains information like the source and destination IP addresses, the protocol being used (e.g., HTTP, TCP), and the data itself. You will be introduced to packet analysis tools, such as Wireshark. This is a popular and powerful network protocol analyzer. It allows you to capture network traffic and inspect the contents of individual packets. Use Wireshark to capture network traffic. This involves selecting the network interface you want to monitor (usually your Ethernet or Wi-Fi adapter) and starting the capture. As traffic flows, Wireshark will display the packets in real-time. Learn how to filter and analyze the captured packets. Wireshark provides a range of filtering options that help you to narrow down the traffic. You can filter by protocol, IP address, port, and more. Look for specific traffic like HTTP requests, DNS queries, or suspicious connections. Examine the packet headers and payloads. Each packet is made up of a header and a payload. The header contains information about the packet (source and destination addresses). The payload contains the actual data being sent. Look for clues in the headers and payloads that might indicate vulnerabilities or malicious activity. For example, you might be looking for unencrypted passwords or other sensitive information.

Day 5: Vulnerability Scanning and Exploitation

Day 5 is where things get real! You'll dive into vulnerability scanning and exploitation, which is a core skill for any ethical hacker. This day typically involves using tools to identify vulnerabilities in systems and then exploiting those vulnerabilities to gain access or achieve a specific goal. You'll learn how to think like an attacker and how to protect against these attacks. You'll be introduced to vulnerability scanners. These are tools that can automatically scan systems for known vulnerabilities. Popular tools include OpenVAS and Nessus. Use them to find potential weaknesses. You'll also learn the basics of penetration testing. This involves simulating attacks to identify vulnerabilities in a controlled environment. The goal is to find weaknesses before a malicious attacker does. Identify the target system. The challenge will most likely provide you with a target system, perhaps a web application or a server. You'll need to know the IP address or hostname of the target. Then, scan the target. Use a vulnerability scanner to scan the target system. These scanners automatically check for common vulnerabilities, misconfigurations, and other security flaws. Analyze the scan results. The scanner will generate a report showing any vulnerabilities found. The report will usually include a description of the vulnerability, its severity, and sometimes even a recommended solution. Exploit the vulnerability, if possible. Once you've identified a vulnerability, try to exploit it to gain access to the target system. This might involve using a pre-built exploit or crafting your own exploit. Remember to always get permission before performing any penetration testing.

Day 6 and Beyond: Continued Learning

Days 6 and beyond often build upon the skills you've acquired in the previous days. You might encounter more complex challenges, explore different types of vulnerabilities, and learn advanced techniques. Keep in mind that continuous learning is super important in cybersecurity. The field is constantly evolving, so staying up-to-date with the latest threats and technologies is key.

Continue practicing. The more you practice, the more comfortable you'll become with the tools and techniques. Try different scenarios, experiment with various exploits, and challenge yourself with advanced tasks. Explore additional TryHackMe rooms. TryHackMe offers a vast library of rooms covering various topics, from web exploitation to malware analysis. Dive into areas that interest you. Read up on new vulnerabilities. Stay informed by reading security blogs, watching webinars, and following cybersecurity news. Keep learning new skills like programming, reverse engineering, and cloud security. These skills are often in demand.

General Tips for Success

• Read the Instructions Carefully: Always carefully read the instructions of each challenge. They often provide valuable hints and information. Also, make sure to understand the question, if there is a question to answer, it's very important to understand it.
• Google is Your Friend: Don't hesitate to use Google or other search engines to find information, solutions, or explanations. You can look for similar rooms, or ask questions on forums.
• Ask for Help: Don't be afraid to ask for help from the TryHackMe community or online forums. If you get stuck, there are many people willing to lend a hand.
• Document Your Work: Keep track of the steps you take and the commands you use. This will help you learn and also help you if you need to revisit the challenge later.
• Have Fun! Cybersecurity can be a challenging field, but it can also be a lot of fun. Embrace the learning process and enjoy the challenges.

Conclusion

Congratulations on completing this walkthrough of the Advent of Cyber 2020 on TryHackMe! Remember, this is just the beginning of your cybersecurity journey. Keep learning, keep practicing, and never stop exploring. Good luck, and happy hacking!