🐧 Fikklish – Proving Grounds Practice Walkthrough

This repository contains my full walkthrough of the Fikklish machine from Offensive Security’s Proving Grounds Practice.

The lab focuses on exploiting a Remote Code Execution (RCE) vulnerability in Weblate 4.11 (CVE-2022-23915), followed by privilege escalation via argument injection in a vulnerable Ruby git gem (CVE-2022-25648).

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🎯 Objectives

• Perform full enumeration and identify attack surface
• Achieve initial access via Weblate RCE
• Stabilize access through reverse shell and SSH key persistence
• Escalate privileges to root via argument injection
• Extract both user and root flags

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🧠 Key Concepts Covered

• Web application enumeration and contextual credential discovery
• Exploiting Mercurial/Git-based RCE via configuration injection
• Validating exploitation using tcpdump (ICMP callback)
• Reverse shell troubleshooting (egress filtering, port selection)
• SSH key persistence for stable access
• Privilege escalation via argument injection in Ruby git gem
• Understanding real-world instability (Redis errors, service locks, environment resets)

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⚠️ Notes

• This write-up is intended for OSCP / OSCP+ level learners
• Some steps require analytical thinking rather than brute-force approaches
• The target environment may behave inconsistently (e.g. Redis failures, locking issues), and manual resets may be required

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📄 Walkthrough

The full walkthrough is available here:

👉 Fikklish Writeup (PDF)

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🔓 Sharing & Usage

Feel free to share, reference, and reuse this write-up for learning and educational purposes.
If you build upon it or reference it publicly, attribution is appreciated.

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🏁 Completion

• User flag: ✅
• Root flag: ✅

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✍️ Author

Created as part of Offsec Singapore Chapter meetup.