DEV Community: Dallen Sadru

Can You Trace a Hidden Beacon to Its Source? A Free Digital Forensics & Reverse Engineering Challenge

Dallen Sadru — Tue, 28 Jul 2026 12:10:28 +0000

Every file tells a story.

Sometimes it's obvious. Other times, it's buried beneath layers of data, hidden artifacts, and carefully crafted deception. In the real world, security analysts spend countless hours investigating files that appear completely ordinary until they discover they're anything but.

That's exactly the idea behind The Beacon Protocol.

We've built a free Capture The Flag (CTF) challenge designed around digital forensics, reverse engineering, and the investigative mindset used by modern SOC and threat intelligence teams.

The Story

A specimen recovered during a routine threat intelligence sweep appears harmless at first glance.

However, investigators believe it's quietly transmitting a signal to an unknown destination.

Your mission is simple:

Find the beacon.

Understand what it's doing.

Follow it all the way back to its source.

Nothing is handed to you. Every discovery reveals the next piece of the investigation until you recover the final mission flag.

What You'll Practice

Unlike many beginner CTFs that focus on isolated puzzles, The Beacon Protocol follows a chained investigation where every stage builds upon the previous one.

You'll encounter techniques involving:

Digital Forensics
File and data extraction
Reverse Engineering
Network traffic analysis
Multi-stage investigations
Thinking like a real incident responder

If you're learning malware analysis, DFIR, or reverse engineering, this challenge is a practical way to sharpen those skills.

Who Is It For?

The challenge is suitable for:

Security students
Reverse engineers
Digital forensics analysts
SOC analysts
Blue teamers
Anyone interested in cybersecurity investigations

No team is required, and participation is completely free.

Ready to Investigate?

If you think you can trace the beacon back to its source, read the briefing and download the specimen.

Challenge: The Beacon Protocol

Read the mission briefing and start your investigation:

https://ctf.astralguard.online/events/the-beacon-protocol

Expected flag format:

ASTRA{...}

Every beacon has a source. Find yours.

Most people think OSINT (Open Source Intelligence) is only for OSINT Analysts. It isn’t

Dallen Sadru — Mon, 20 Jul 2026 08:44:57 +0000

If you’re in cybersecurity, chances are you’re already relying on OSINT whether you realize it or not.

🔍 Hunting for indicators of compromise?

You’re using OSINT.

🔍 Investigating a phishing campaign?

You’re using OSINT.

🔍 Profiling an organization’s attack surface before a penetration test?

That’s OSINT.

🔍 Verifying digital identities, researching domains, tracing infrastructure, or gathering threat intelligence?

All OSINT.

The reality is this:

Cybersecurity isn’t just about finding vulnerabilities. It’s about finding information others overlook.

The professionals who stand out aren’t necessarily the ones with the most tools they’re the ones who know where to look, how to correlate information, and how to turn publicly available data into actionable intelligence.

Write on Medium
That’s exactly what our Open Source Intelligence (OSINT) course at AstralGuard Cyber Academy is designed to teach.

Over five weeks of hands-on training, you’ll learn to:

• Perform advanced Google dorking and digital investigations.

• Conduct structured social media intelligence (SOCMINT).

• Map domains, IPs, and network infrastructure.

• Correlate digital identities across multiple platforms.

• Extract intelligence from public documents and metadata.

• Use professional tools such as Maltego, Shodan, theHarvester, IntelligenceX, Metagoofil, Mitaka, and more.

• Think and investigate like a professional analyst.

Whether you’re an aspiring cybersecurity professional, SOC analyst, penetration tester, DFIR practitioner, threat hunter, researcher, or simply curious about digital investigations, OSINT is one of the most valuable skills you can add to your toolkit.

If you’re ready to move beyond searching and start investigating, explore the course here:

🌐 https://academy.astralguard.online/courses/open-source-intelligence

The internet is full of intelligence.

The difference is knowing how to uncover it.

FREE COMMUNITY SESSION: FILE UPLOAD ATTACKS — NULL BYTE INJECTION, DOUBLE EXTENSIONS & RCE

Dallen Sadru — Fri, 17 Jul 2026 14:02:56 +0000

🔐 One weak filter. One uploaded file. Full server takeover.

Most developers think file upload validation is a solved problem. It's not and it's one of the most exploited attack surfaces in production web applications today.

On Saturday, 18th July 2026, AstralGuard is hosting a free, live technical session breaking down exactly how file upload vulnerabilities lead to Remote Code Execution and how to stop it before it happens to your application.

What we'll cover:
🔹 File Upload Attacks how weak validation logic (blacklists, MIME trust, extension parsing) opens the door to exploitation
🔹 Double Extension Attacks how filenames can bypass filters and get executed as code instead of served as images
🔹 Null Byte Injection the technique that broke early filename validation, why it worked, and why understanding legacy attack classes still matters for secure development today
🔹 Remote Code Execution (RCE) the full exploitation chain, live, in an isolated lab environment from upload to execution to what it can mean for full server compromise
🔹 Developer Mistakes the real, common patterns in production code that create these vulnerabilities in the first place
🔹 Defensive Engineering practical, actionable mitigations: proper whitelisting, content verification, server-level hardening, and secure upload architecture

Why this matters:
Whether you write the code, secure it, or break it for a living understanding this attack class from both sides makes you better at your job.

This session is built to leave you with real, applicable knowledge, not just theory.

Who should attend:
✅ Developers who want to secure their own applications
✅ Cybersecurity students building practical, hands-on skills
✅ Security professionals looking for a sharp technical refresher
✅ Anyone curious about how real-world exploitation actually works

No prior offensive security experience required. Just bring curiosity.

📅 Date: Saturday, 18th July 2026
🕞 Time: 3:30 PM EAT
📍 Platform: Google Meet
🔗 Join link: available at https://meet.google.com/gye-bttr-aip

Free. Open to everyone. Limited only by how many people show up ready to learn.
Save the date. Bring a colleague. See you there. 🚀

🖤 OPERATION VANTABLACK – FREE COMMUNITY CTF WALKTHROUGH

Dallen Sadru — Thu, 09 Jul 2026 06:45:30 +0000

Most people learn Digital Forensics by reading about it.

The fastest way to improve is by watching an investigation unfold and understanding the thinking behind every step.

This Saturday, we're opening our community CTF walkthrough to everyone.

🔍 OPERATION VANTABLACK – Free Community CTF Walkthrough

We'll work through a realistic digital forensics challenge from start to finish, demonstrating how investigators approach evidence, validate findings, and connect the dots.

During the session, we'll explore practical techniques such as:

🖤 Investigating suspicious files

🖤 Recovering hidden information

🖤 Cracking protected archives

🖤 Analyzing documents, images, and audio artifacts

🖤 Following the complete chain of evidence using real DFIR methodologies

Whether you're taking your first steps in cybersecurity or sharpening your investigative skills, this session is designed to give you practical experience you can immediately apply.

📅 Date: Saturday, July 11, 2026

🕒 Time: 3:30 PM – 6:00 PM (EAT)

💻 Location: Online via Google Meet

🎯 Want to attempt the challenge before the walkthrough?

CTF: https://ctf.astralguard.online/events/operation-vantablack

💬 Join our cybersecurity community:

https://discord.gg/z4VhJXcFQ

Bring your curiosity, your questions, and your investigative mindset. By the end of the session, you'll have seen how experienced analysts approach a forensic investigation not just the tools they use, but the reasoning behind every decision.

See you on Saturday.

CyberSecurity #DigitalForensics #DFIR #CTF #BlueTeam #IncidentResponse #CyberSecurityCommunity #ThreatHunting #CyberTraining #AstralGuard #LearnCyberSecurity #AstralGuardCyberAcademy

🖤 OPERATION VANTABLACK — Free Digital Forensics CTF 🖤

Dallen Sadru — Sat, 04 Jul 2026 10:27:22 +0000

Ever wondered what real cybersecurity investigation actually feels like?
AstralGuard is running a free, open Capture The Flag challenge — a hands-on forensics mystery where you investigate a "routine" file that's hiding a lot more than it looks.

What you'll actually practice:
✅ Real digital forensics techniques
✅ Investigation & analytical thinking
✅ Tools used by actual security analysts
✅ Problem-solving under a real challenge, not a tutorial

Who's it for?
Students, security beginners, hobbyists, working professionals — anyone curious enough to try. No CTF experience needed. No entry fee. No team required.

What you get:
📌 Practical, resume-worthy skills
📌 Bragging rights + leaderboard recognition
📌 A genuinely fun way to learn forensics by doing it, not reading about it

👉 Full details & registration: https://ctf.astralguard.online/events/operation-vantablack
Free. Open. Yours to solve.
See you on the leaderboard. 🕵️‍♂️

🚩 Free CTF Event This Saturday — Come Learn With Us

Dallen Sadru — Wed, 24 Jun 2026 19:20:15 +0000

If you've ever been curious about cybersecurity but didn't know where to start, this one's for you.

Astral Guard Cyber Academy is hosting a free, community-driven Capture The Flag (CTF) solving session this Saturday, and we'd love to have you join us.

🔍 Challenge: Ghost in the Pixels

📂 Category: Digital Forensics & Steganography

🎯 Difficulty: Beginner

📅 Saturday, June 27, 2026

🕞 3:30 PM – 6:30 PM

💻 Online via Google Meet

👉 Join here: https://meet.google.com/ndk-qwcj-fbk

We'll be investigating a real forensics challenge together analyzing evidence, uncovering hidden data, and learning hands-on techniques that actual analysts use. No experience needed. Just bring your curiosity.

This is the kind of session where you leave knowing more than when you came in.

We're also building something bigger.

Astral Guard has a growing cybersecurity community on Discord where analysts, learners, and enthusiasts connect, share resources, and sharpen their skills together beginners absolutely welcome.

🔗 Join the community: https://discord.gg/sp9uUefv4v

See you Saturday. 👾

Cybersecurity #CTF #DigitalForensics #InfoSec #Steganography #BeginnersWelcome #AstralGuardCyberAcademy #CyberCommunity

Join AstralGuard Discord Community

Dallen Sadru — Sun, 21 Jun 2026 23:48:46 +0000

🛡️ Are you serious about cybersecurity?
Then you need to be in this server.
AstralGuard Cyber Academy is building one of the most active cybersecurity communities online — and we want you in it.
Whether you're just starting out or already deep in the field, this is where you come to learn, grow, and connect with people who are on the same path.
Inside the Discord you'll find:

🔍 CTF challenges and forensics discussions

💻 Ethical hacking and web security channels

🧠 Study groups and peer support

📢 Early access to events, solve books and free resources

👥 A community that actually helps each other — no gatekeeping
We run live CTF events, drop free resources regularly, and the AstralGuard team is active and answering questions every day.
If you've been learning alone, that stops today.
👇 Join free. No experience required.

🔗 https://discord.gg/sp9uUefv4v

🕵️ You Are Invited — Live Digital Forensics Investigation in Progress

Dallen Sadru — Tue, 05 May 2026 07:27:51 +0000

AstralGuard Cyber Academy is about to do something we have never done before and if you miss it this Wednesday you are genuinely going to regret it.

You know how we always talk about steganography and digital forensics? How investigators find hidden data inside files that look completely normal to everyone else?

On Wednesday 6th May from 4:30PM to 8:30PM we are not talking about it anymore.

We are DOING it. Live. In front of you. 👀

There is a real evidence file. A suspicious image seized during a cybercrime investigation. To anyone who looks at it it is just a picture. Nothing suspicious. Nothing unusual. Just an image sitting there.

But something is buried inside it.
Hidden data, concealed so deep that most people would never know it was there. And we are going to find it. Live on screen. Every command.

Every tool. Every single moment where the invisible becomes visible.
No theory. No slides. No "this is how it works in practice." Just actual forensics happening in real time while you watch.

🔥 We are going to verify evidence integrity the way law enforcement does it. We are going to rip through the file and expose what it is really hiding. We are going to detect steganographic manipulation that the naked eye cannot see.

We are going to extract the hidden data live. And we are going to break down the encryption the suspect used to lock it all away.
This is the kind of session that changes how you see every image file for the rest of your life.

Now here is the thing 👇
This is NOT happening on Google Meet.
This is happening inside the AstralGuard Cyber Academy OFFSEC LAB 🧪

The OFFSEC LAB is our private hands on cybersecurity environment where real skills get built. This is where things get serious.

If you are not in there yet you are already missing out and Wednesday is going to make that even more clear.
Joining is simple. Go here right now 👇
🔗 https://academy.astralguard.online/offsec-lab
Follow the steps, get yourself in, and make sure you are there on Wednesday at 4:30PM sharp.

Two hours. One suspicious file. Zero theory. Pure forensics.

💀Wednesday 6th May 2026
4:30PM to 6:30PM EAT
AstralGuard Cyber Academy OFFSEC LAB only
Do not be late. Do not miss this. See you in the lab. 🔐

🚨 Don't start bug bounty before you do this.

Dallen Sadru — Tue, 28 Apr 2026 13:46:04 +0000

And if you already started and haven't found your first bug yet — this is exactly why.
Most people jump into bug bounty programs copying other people's methodology without actually understanding what they're looking at. They spend hours on a target, find nothing, get frustrated and quit. Not because they're not smart enough — but because nobody taught them how to read a web application.
That changes here.
We're opening 10 seats for our Practical Web Security Bootcamp. 10 days. No distractions. No theory dumping. Just you and the lab.

🎯 Who this is for:
→ You want to start bug bounty but don't know where to begin
→ You've been doing bug bounty and still haven't landed your first bug
→ You're studying cybersecurity and want skills that actually show up on the job
→ You're a developer who wants to understand how your own applications can be compromised
→ You're tired of watching tutorials and want to actually do something

💥 What happens in these 10 days:
🔬 You get unlimited access to our live lab environment for the full 10 days — practice as many times as you want, break things, learn from it, do it again
🧠 You learn to look at a web application's frontend behavior and understand exactly what is happening on the server — without touching the source code. That skill alone will change how you approach every target you ever touch
🔍 You will be able to identify the most critical web security flaws that show up across thousands of real applications — the exact vulnerabilities that bug bounty hunters get paid to find
🏁 At the end you face a capstone security assessment — a real target, your skills, no hints. You attack it, analyze it, document it like a professional
🎓 You walk away with a verifiable certificate in Practical Web Security — not a participation badge, you only get it when you pass the final assessment

⚠️ This is not a course you sit back and watch.
This is 10 days of going dark. No casual scrolling, no half-attention. You commit, you grind, and you come out the other side actually knowing what you're doing.
That's why we cap it at 10 students only. Small group. Real attention. Real results.

🗓️ Starts May 13
⏳ Registration closes May 10
👥 10 seats. That's it.
If you've been waiting for something that actually takes you seriously —
This is it. Grab your spot now
👇

https://selar.com/12og490k82

🔐 Think Two-Factor Authentication Makes You Safe? Think Again.

Dallen Sadru — Fri, 03 Apr 2026 09:02:11 +0000

For years, Two-Factor Authentication (2FA) has been promoted as a critical layer of security — and rightly so. It adds protection beyond just a password.

But here’s the uncomfortable truth:

2FA is not a guarantee of security. It is only as strong as its implementation.

In real-world applications, we continue to see systems where:
• The 2FA step can be bypassed due to flawed logic
• Authentication flows trust client-side input too much
• Weak OTP mechanisms allow brute-force attacks
• Session handling mistakes expose fully authenticated access

In these cases, attackers don’t need your password.
They don’t need your device.

They only need one thing: a mistake in the system’s design.

🎯 Why This Matters

Modern attackers are no longer focused on breaking encryption —
they are focused on exploiting logic flaws and misconfigurations.

A single oversight in how 2FA is implemented can lead to:
→ Full account takeover
→ Unauthorized access to sensitive systems
→ Severe business and reputational damage

💻 What Professionals Need to Learn

Understanding security today means going beyond theory. It requires:
• Analyzing real authentication flows
• Identifying trust boundaries in applications
• Testing for bypass techniques in controlled environments
• Thinking like an attacker to defend effectively

🚀 Take the Next Step

At AstralGuard Cyber Academy, we focus on practical, real-world cybersecurity training — not just concepts, but execution.

Our Practical Web Hacking Course is designed to help you:
• Master real exploitation techniques
• Understand vulnerabilities like 2FA bypass in depth
• Build hands-on skills used in penetration testing and bug bounty

If you’re serious about cybersecurity and want to move from theory to real skill:

👉 Enroll here:
academy.astralguard.online/courses

🧠 Security is not about adding more layers. It’s about ensuring those layers cannot be broken.

CyberSecurity #WebSecurity #EthicalHacking #BugBounty #Pentesting #InformationSecurity

🚀 LIVE SESSION TODAY – Host Header Injection Attack Chaining

Dallen Sadru — Wed, 01 Apr 2026 06:10:38 +0000

Today we’re going beyond basics.

In this session, you’ll learn how attackers use Host Header Injection to manipulate application logic and perform password reset poisoning — leading to full account takeover.

💻 What to expect:
• Live, real-world demonstration
• Step-by-step attack chaining
• Learn how reset tokens can be captured and abused

📅 Date: 1st April 2026
⏰ Time: 4:30 PM (EAT)
🏫 Platform: Classroom on BigBlueButton

This is advanced, practical knowledge — not something you find in typical tutorials.

⚠️ Strictly for enrolled students only.
If you’re not enrolled, please do not join.

🔥 Be ready. This is where things get real.

— AstralGuard Cyber Academy

📅 Don’t miss any of our hacking events:
https://academy.astralguard.online/calendar

🚨 Stop watching cybersecurity tutorials. Start thinking like a real pentester.

Dallen Sadru — Tue, 31 Mar 2026 05:28:43 +0000

Most people spend months learning “theory”…
…but freeze the moment they face a real target.

That’s the gap.

And that’s exactly what our Offensive Web Penetration Testing program fixes.

💻 This is NOT a theory course.
This is a fully practical, hands-on experience where you:

✔️ Exploit real-world web vulnerabilities
✔️ Work inside realistic lab environments
✔️ Learn how attackers actually think and operate

🎯 What makes this different?

🔹 100% Practical Training
No fluff. No wasted time. You build real, job-ready skills.

🔹 Industry-Ready Reporting Skills
Learn how to:

Write professional penetration testing reports
Create vulnerability disclosure reports
Clearly explain security issues to employers and clients

🔹 Peer Learning Environment
You won’t learn alone.
Collaborate, discuss, and grow with others on the same path.

🔹 Verifiable Certificate
Show proof of your skills — something you can actually present with confidence.

🚀 What can you do after this course?

This isn’t just “learning” — it’s positioning you for real opportunities:

💼 Web Application Penetration Tester
💼 Bug Bounty Hunter
💼 Security Analyst (Blue/Red Team)
💼 Vulnerability Assessment Specialist
💼 Cybersecurity Consultant
💼 SOC Analyst (with offensive edge)
💼 Freelance Pentester
💼 Junior Red Team Operator

🧠 Why this matters

Companies don’t hire people who watched courses.

They hire people who can:
→ Find vulnerabilities
→ Exploit them
→ Explain them clearly

That’s exactly what you’ll learn here.

🔥 If you’re serious about breaking into cybersecurity…

👉 Read more about the course:
https://selar.com/40nr6e776f

👉 Or explore the full AstralGuard Cyber Academy catalog:
https://selar.com/m/astralguard-cyber-academy

⚠️ Don’t stay stuck in theory.
Step into real-world hacking.

CyberSecurity #EthicalHacking #Pentesting #BugBounty #WebSecurity