Advanced Web Exploitation
Foundational web challenges hide flags in cookies and single injections. Advanced ones make you chain bugs: stored XSS that steals an admin bot's session, SSRF that pivots to an internal service, XXE that reads server files, and WebAssembly you have to decompile. This path assumes you are fluent with dev tools, cookies, and basic SQL and SSTI injection.
Guides for this path
Read these alongside the challenges below. The first one orients you; the rest go deeper on the techniques each step needs.
- sqlmap for CTF: Every Flag That Matters, and What to Do When It Finds NothingA practical sqlmap workflow for CTF: request files, level and risk, technique selection, tamper scripts, second-order injection, and the failure checklist.
- XSS for CTF: A Ladder from alert(1) to CSP BypassXSS for CTF: a four-rung ladder from reflected to CSP bypass with paste-ready payloads, picoCTF receipts, and 2024-2026 production CVEs at every rung.
- SSRF for CTF: From localhost Pivots to Cloud MetadataServer-Side Request Forgery for CTF: whose network does the server trust? The ladder from a url= parameter to 127.0.0.1, cloud metadata, and gopher RCE.
- XXE for CTF: XML External Entity AttacksXXE for CTF web challenges: file-read XXE, blind out-of-band exfiltration, XXE-to-SSRF, error-based leaks, and parameter entities, with real payloads and curl.
- LFI for CTF: From /etc/passwd to RCELocal File Inclusion explained patiently: the trust failure behind PHP's include(), the four moves from /etc/passwd to RCE, and which still work in 2026.
- JavaScript Deobfuscation for CTF: Hook the Sink, Not the SourceDeobfuscate CTF JavaScript by hooking eval, Function, and atob instead of reading minified code. Includes WebAssembly reversing and a DevTools workflow.
- Step 01
Advanced Injection and Filter Bypass
Real injection rarely works on the first payload because input is filtered. ORDER ORDER hides the flag behind a UNION SELECT that only fires when a report is generated, and msfroggenerator2 wraps a server-side injection in stricter sanitization you have to bypass before you can execute commands.
- Step 02
Exploiting Admin Bots
Many web challenges run a headless browser that visits a page as an authenticated admin. Your job is to plant a payload the bot will execute: stored XSS that exfiltrates its session cookie, or a CSRF or race condition that makes it render something it should not. This is how cookie theft works in the real world.
- Step 03
SSRF and Internal Pivoting
Server-Side Request Forgery turns the vulnerable server into your proxy into the internal network. The hardest web challenges chain SSRF with a second bug, like template injection, to reach a service that is not exposed to the internet and exfiltrate a flag from behind it.
- Step 04
XML, XPath, and Path Traversal
Structured input formats open their own attack class. X marks the spot exploits an XXE or XPath injection to read server-side files, and notepad abuses backslash path traversal to write a Jinja2 template that becomes SSTI when you trigger it. Understanding how parsers resolve paths and entities is the key.
- Step 05
Client-Side and WebAssembly Reversing
Not all web logic runs on the server. The Java Script Kiddie challenges make you reverse an obfuscated JS image decoder and brute-force its keys, while the Some Assembly Required series hands you WebAssembly modules with layered XOR and encryption you must decompile and peel apart.