Hackday on Anthrace | CTF Writeups

HackDay - Stegano

Wed, 30 Jul 2025 00:00:00 +0000

In this challenge, we are provided with a .wav file that, at first glance, appears to be a simple audio file. Our task is to analyze the file and uncover a hidden flag.

Step 1: Playing the Audio Link to heading

I started by playing the audio, expecting something unusual—perhaps some hidden message or distortion—but everything sounded normal. There was no apparent clue in the audio playback.

HackDay - Stegano & Forensic

Wed, 30 Jul 2025 00:00:00 +0000

Forensic Challenge - Hidden Flag Extraction Link to heading

In this challenge, we have a ZIP file containing a log file and two images.

Step 1: Log File Analysis Link to heading

I began by analyzing the log file and found five encoded words. I used dcode.fr to decode them:

ercbafr (ROT13) → reponse

c29sdXRpb24= (Base64) → solution

HackDay - Web

Wed, 30 Jul 2025 00:00:00 +0000

Exploiting an XSS Vulnerability in a Blog with Moderator Visit Link to heading

In this challenge, we have a blog with a user registration and login system.
We know that the admin (or the moderator bot) will visit our profile when we register and when we post an article.

A source code leak is also available.

Step 1: Analyzing the Source Code Link to heading

Looking at the leaked source code, we notice an attempt at sanitization of the fields, but it is performed after the .save(), meaning that even if an error is displayed, the data is already stored in the database.

HackDay - Web

Wed, 30 Jul 2025 00:00:00 +0000

Flask Web Challenge - Template Injection Analysis Link to heading

In this challenge, we have a downloadable folder containing several files.

Step 1: Identifying the Web Framework Link to heading

By examining the requirements.txt and app.py files, we confirm that the application is built using Flask.

Step 2: Examining the Docker Configuration Link to heading

Looking into the docker-compose.yaml file, we notice that the application is using templates as an environment variable, which could be a potential security risk.

HackDay - Web

Wed, 30 Jul 2025 00:00:00 +0000

SQL Injection and Sensitive Data Retrieval

In this challenge, we are given a form with two fields: username and password. Our goal is to exploit a SQL Injection vulnerability to extract sensitive data from the database.

Step 1: Testing Basic Injection Link to heading

I started by testing a simple SQL injection in the password field. Here’s the payload I used:

username=admin&password='OR''='

Result: The server returns a list of users present in the database: