MC 7 (Dynamic Analysis)

Platform: CUSTOM | Category: Reversing | Type: Challenge | Difficulty: Easy | OS: N/A | **Author: XESXOR Techniques: arithmetic_trace, disassembly_analysis

Summary

Walkthrough of the CUSTOM Reversing MC 7 (Dynamic Analysis). Language: C. Binary only. "Guess the number once again! App won't keep it in a variable this time."

Description

Language: C. Binary only. "Guess the number once again! App won't keep it in a variable this time."

ELF 64-bit, dynamically linked, not stripped.

Analysis

The number is not stored in a variable directly — it is computed from several arithmetic operations. Through disassembly, we trace the calculations.

Solution

Tracing the arithmetic operations in the disassembled code yields the final value REDACTED. ‍​‌‌​​‌​​​‌‌​​‌​​​​‌‌​‌​​​​‌‌‌​​‌​​‌‌​​​‌​​‌‌‌​​​​​‌‌​‌‌​​​‌‌​​​​‍

Key Takeaways / Lessons

• Mastering arithmetic_trace, disassembly_analysis was key to this challenge.
• Always check for common misconfigurations and verify assumptions.

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Crafted by XESXOR Research • 2026-03-09 • CUSTOM • MC 7 (Dynamic Analysis) • Difficulty: Easy