Offensive SecurityPenetration Tester · Europe

ctxzero

Penetration tester & cybersecurity researcher.

I break web apps, networks and Active Directory to understand how attacks really work - and I keep learning, building and sharpening the craft every day.

Operator
ctxzero
Focus
Web · Net · AD
Certifications
CPTS · eJPT
Availability
Open to opportunities
01Summary

Who's behind the handle

I'm a penetration tester and cybersecurity researcher focused on offensive security - web application, network and Active Directory pentesting.

I work manual-first, backed by the right tooling, and care about understanding why something is exploitable, not just that a scanner flagged it. Most of what I learn ends up here as writeups and in my own tooling. I'm constantly pushing to go deeper, level up my skills and take on harder targets - this is a craft I'm in for the long run.

FocusWeb · Network · Active Directory
ApproachEnumerate everything
CurrentlySharpening web app skills · getting into blue team & forensics
BasedEurope
02Capabilities

Where I operate

Web ApplicationManual + tooling, verified findings
Burp SuiteSQLiXSSSSRFIDORAuth bypassFile uploadmore
NetworkFull kill-chain methodology
RustScanEnumerationPivotingTunnelingLateral movementPrivEscmore
Active DirectoryMisconfig → domain compromise
BloodHoundKerberoastingAS-REP RoastingNTLM relayADCS abuseDCSyncmore
Scripting & ToolingAutomation & exploit PoCs
PythonBashPowerShellExploit PoCsAutomationmore
01
Recon
Map the attack surface and enumerate thoroughly.
02
Exploitation
Verify and chain real, exploitable weaknesses.
03
Post-exploitation
Escalate, pivot, demonstrate impact.
04
Documentation
Write it up clearly - reproducible steps, real impact.
03Credentials

Certifications

CPTS badge - Hack The Box

Certified Penetration Testing Specialist

Hack The Box

A 10-day, fully hands-on exam: blackbox web, external and internal penetration testing against a real-world Active Directory network hosted in HTB's infrastructure and accessed over VPN. It starts with a letter of engagement laying out objectives, requirements and scope - and ends with a commercial-grade penetration test report. CPTS covers both the testing itself and communicating the findings professionally.

Verified Verify ↗
eJPT badge

eJPT

INE / eLearnSecurity
Verify ↗
Cyber Threat Intelligence badge

Cyber Threat Intelligence

ArcX
04Team

v1olet

I'm co-captain of v1olet - an independent offensive security research team working on penetration testing, red team operations and vulnerability research.

We compete internationally as a CTF team. As co-captain I take on the organisational side - roster, which events we play, how we split the board - and I play the competitions myself alongside the rest of the team. Different pressure than a lab box, and the best training there is.

3rd place

BroncoCTF - 3rd of 1065+ teams

Our first competition as a team

The first event we played together, straight onto the podium against a field of more than a thousand teams - categories split across the roster: web, pwn, rev, crypto, forensics, osint, misc and beginner.

Podium CTFtime ↗
05Selected work

Things I've built

PortHunt - port scanner menu

PortHunt

Python · Tooling

A high-speed Python port scanner with built-in CVE lookup and JSON/HTML reporting - fast, scriptable and report-ready.

PythonAsyncCVE lookupJSON/HTML output
06Field notes Source

Writeups & research

HTB machine writeups - recon to root, read right here on the page. Click any card to open the full writeup.

07Contact

Establish contact

GitHub
@ctxzero
Hack The Box
View profile
LinkedIn
Luis Schlegel
TryHackMe
/p/ctxzero
© 2026 ctxzero - Penetration TesterREF · CTX-0 / 2026
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