picoCTF Solutions
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Bit-O-Asm-1

Published: March 5, 2024Updated: December 9, 2025

Description

Inspect the provided assembly dump and report the value placed into EAX. Convert the hexadecimal literal into decimal before wrapping it in picoCTF{...}.

Setup

Assembly readingDownload disassembler-dump0_a.txt

Grab the assembly dump and open it in your editor.

Locate the MOV that writes a constant into EAX.

wget https://artifacts.picoctf.net/c/509/disassembler-dump0_a.txt
cat disassembler-dump0_a.txt

Solution

  1. Step 1Find the immediate value
    The dump shows mov eax, 0x30, so the register ends with hexadecimal 0x30 at function exit.
  2. Step 2Convert to decimal
    Translate 0x30 to decimal (48) via printf, python, or any converter, then format picoCTF{48}.
    printf "picoCTF{%d}\n" 0x30

Flag

picoCTF{48}

Every challenge in the Bit-O-Asm series hides the answer in a MOV/arith instruction-reading the dump carefully is all you need.