HTB KOBOLD

Overview

Kobold is a Medium-difficulty Linux machine featuring Docker escape vulnerabilities and web application exploitation. This machine teaches:

• Web application reconnaissance
• CVE exploitation for modern frameworks
• Docker container breakout techniques
• Privilege escalation via container permissions

Enumeration

Port Scanning

Initial reconnaissance reveals standard web services and potential custom applications.

Key Services:

• HTTP web application
• Possible custom service ports
• Container management interfaces

Web Application Analysis

The target hosts a web application that appears to be:

• Built with modern frameworks
• Potentially vulnerable to known CVEs
• Running containerized services

Initial Foothold

Vulnerability Discovery

The path to initial access involves:

1. CVE-2026-23744 - MCPJam Inspector RCE
2. Exploiting web framework vulnerabilities
3. Gaining shell access through unsafe deserialization or code execution

Exploitation Hints

Key areas to investigate:

• Application version disclosure
• User input handling
• File upload functionality
• API endpoints

User Access: Once inside, you'll find yourself in a containerized environment.

Privilege Escalation

Container Analysis

After gaining initial access, examine:

• Container runtime and permissions
• Available Docker sockets
• Group memberships
• Mounted volumes

Docker Escape

The privilege escalation involves:

1. Identifying operator group membership
2. Exploiting Docker socket access
3. Container breakout to host system
4. Root access on the underlying host

Key Concepts

• Understanding Docker socket exploitation
• Container vs host filesystem access
• Privilege abuse in containerized environments

Root Flag Location: /root/root.txt (on host system)

Key Takeaways

• Container security is critical
• Docker socket exposure is dangerous
• Group memberships matter
• Version disclosure aids exploitation

Tools Used

• nmap - Port scanning
• gobuster / ffuf - Web enumeration
• CVE-specific exploits
• docker commands for escape
• Standard Linux privilege escalation tools