HTB BlockSynergy Complete Writeup - Blockchain PoW Mining, SSRF 0.0.0.0 Bypass, URL Userinfo Command Injection, Smart Contract Path Traversal and TOCTOU SUID Race to Root

A comprehensive penetration testing guide covering proof of work blockchain mining to unlock VIP node registration, SSRF filter bypass with 0.0.0.0 to reach a localhost only admin panel, command injection through URL userinfo credentials with hex encoding payload smuggling, arbitrary file write via a smart contract logging engine path traversal to inject SSH keys, hardcoded FTP credential capture from a root cron job, and a TOCTOU race condition against a root restore daemon to extract a SUID root bash shell.

August 30, 2026 • views • 29 min read • 3,513 words

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