Challenge Overview

You are tasked with performing a security assessment on an Android application used by a company to store sensitive employee data. The app utilizes encryption to safeguard the information, but the company has noticed potential vulnerabilities in how the app handles authentication and encryption. Your job is to explore the app, reverse-engineer its APK, and uncover any weaknesses in the encryption or authentication mechanisms that could allow unauthorized access. The goal is to decrypt sensitive user data, identify the flag hidden within the records, and understand how the app could be exploited. The target machine is running an Android OS and is accessible at IP 10.10.1.104. It hosts an application called "androidappcrypt" that features encrypted data and requires participants to bypass authentication and decrypt sensitive information. To complete the challenge, participants must connect to the device, investigate the app's components, and retrieve the hidden flags by analyzing its source code, API interactions, and encryption mechanisms. Each step will guide competitors closer to uncovering the final flag and completing the challenge.

What You Will Learn

  • Android APK reverse engineering, including decompiling the application using tools like jadx (jadx-gui) to inspect source code, activities, API calls, and hardcoded values.
  • Identifying hidden API endpoints and authentication logic, understanding how the app communicates with backend services to retrieve encrypted employee data.
  • Analyzing implemented cryptographic mechanisms, particularly identifying the AES mode, key usage, and transformation strings embedded in the source code.
  • Writing a custom decryption script in Kotlin, applying extracted keys and algorithm parameters to correctly decrypt the encrypted payload.
  • Performing a full mobile application attack chain, from APK analysis → API discovery → crypto analysis → data decryption → flag extraction on the Android target (10.10.1.104).

Program Curriculum

Join over 1 Million professionals from the most renowned Companies in the world!

certificate

Choose the Pro Plan That Fits Your Learning Journey

Invest in your future with flexible Pro subscription plans. Whether you're starting your cybersecurity journey or expanding your expertise, choose the membership duration that works for you and gain access to our complete learning platform.

Monthly Plans
Annual Plans
Save 20% with our annual plans!

Pro

Ideal for continuous learning, offering extensive resources with 900+ courses and diverse Learning Paths to enhance your skills.

$ 599.00
Billed annually or $69.00 billed monthly

What is included

  • Access to 900+ Premium Short Courses
  • 70+ Structured Learning Paths
  • Validation of Completion with All Courses and Learning Paths
  • New Courses Added Every Month
Early Access Offer

Pro +

Experience immersive learning with Practice Labs and CTF Challenges for comprehensive skill-building.

$ 699.00
Billed annually or $79.00 billed monthly

Everything in Pro and

  • 500+ Practice Labs with Guided Instructions
  • 400+ CTF Challenges with Detailed Walkthroughs
  • New Practice Labs and Challenges Added Every Month

Related CTF Challenges

1 of 50