This is from the BlueHensCTF 2021.
Challenge Author: Izzy and ProfNinja
For this challenge, We are given the following information and links:
Here is the mc86 Intro:
Here is the mc86 InitCode:
/give @p minecraft:written_book{title:"Init CPU",author:"UD Cyberscholars",generation:0,pages:[
"{\"text\":\"Click Here First\\n\",\"color\":\"dark_green\",\"bold\":true,\"underlined\":true,\"hoverEvent\":{\"action\":\"show_text\",\"value\":\"Creating RAM\"},\"clickEvent\":{\"action\":\"run_command\",\"value\":\"/setblock ~1 ~ ~ minecraft:lime_shulker_box\"},
\"extra\":[
{\"text\":\"Click Here Second\\n\",\"color\":\"dark_green\",\"bold\":true,\"underlined\":true,\"hoverEvent\":{\"action\":\"show_text\",\"value\":\"Start Timing Belt\"},\"clickEvent\":{\"action\":\"run_command\",\"value\":\"/setblock ~2 ~1 ~ minecraft:command_block[facing=up]{powered:0b,Command:\\\"setblock ~ ~-1 ~ air\\\"}\"}},
{\"text\":\"Click Here Third\\n\",\"color\":\"dark_green\",\"bold\":true,\"underlined\":true,\"hoverEvent\":{\"action\":\"show_text\",\"value\":\"Finishing Timing Belt\"},\"clickEvent\":{\"action\":\"run_command\",\"value\":\"/setblock ~2 ~2 ~ minecraft:chain_command_block[facing=up]{powered:0b,auto:1b,conditionMet:0b,Command:\\\"execute if data block ~-1 ~-2 ~ Items[0].tag.pages[0] run setblock ~ ~-2 ~ redstone_block\\\"}\"}},
{\"text\":\"Click Here Fourth\\n\",\"color\":\"dark_green\",\"bold\":true,\"underlined\":true,\"hoverEvent\":{\"action\":\"show_text\",\"value\":\"Start CPU\"},\"clickEvent\":{\"action\":\"run_command\",\"value\":\"/setblock ~3 ~ ~ minecraft:command_block[facing=east]{powered:0b,Command:\\\"data modify block ~2 ~ ~ Command set from block ~-2 ~ ~ Items[0].tag.pages[0]\\\"}\"}},
{\"text\":\"Click Here Fifth\\n\",\"color\":\"dark_green\",\"bold\":true,\"underlined\":true,\"hoverEvent\":{\"action\":\"show_text\",\"value\":\"Finishing CPU\"},\"clickEvent\":{\"action\":\"run_command\",\"value\":\"/setblock ~4 ~ ~ minecraft:chain_command_block[facing=east]{powered:0b,auto:1b,conditionMet:0b,Command:\\\"data remove block ~-3 ~ ~ Items[0].tag.pages[0]\\\"}\"}},
{\"text\":\"Click Here Sixth\\n\",\"color\":\"dark_green\",\"bold\":true,\"underlined\":true,\"hoverEvent\":{\"action\":\"show_text\",\"value\":\"Placing ALU\"},\"clickEvent\":{\"action\":\"run_command\",\"value\":\"/setblock ~5 ~ ~ minecraft:chain_command_block[facing=east]{powered:0b,auto:1b,conditionMet:0b}\"}}]}"]} 1
Finally, here is the challenge source code:
/give @p writable_book{pages:["/fill ~ ~4 ~ ~6 ~6 ~15 dirt","/fill ~ ~7 ~5 ~6 ~7 ~5 acacia_fence","/fill ~ ~7 ~3 ~6 ~7 ~3 acacia_fence","/fill ~4 ~7 ~1 ~4 ~7 ~7 acacia_fence","/fill ~2 ~7 ~1 ~2 ~7 ~7 acacia_fence","/setblock ~1 ~7 ~10 acacia_fence","/setblock ~2 ~7 ~11 acacia_fence","/setblock ~3 ~7 ~12 acacia_fence","/setblock ~4 ~7 ~13 acacia_fence","/setblock ~5 ~7 ~14 acacia_fence","/setblock ~5 ~7 ~10 acacia_fence","/setblock ~4 ~7 ~11 acacia_fence","/setblock ~2 ~7 ~13 acacia_fence","/setblock ~1 ~7 ~14 acacia_fence","/clone ~4 ~4 ~5 ~6 ~7 ~7 ~ ~-3 ~5","/fill ~1 ~-1 ~6 ~1 ~-2 ~6 air","/summon pig ~1 ~-2 ~6","/clone ~ ~4 ~5 ~2 ~7 ~7 ~ ~-3 ~9","/clone ~1 ~4 ~10 ~5 ~7 ~12 ~ ~-3 ~13","/clone ~2 ~4 ~3 ~4 ~7 ~5 ~ ~-3 ~17","/clone ~ ~4 ~5 ~2 ~7 ~7 ~ ~-3 ~21","/fill ~1 ~-1 ~22 ~1 ~-2 ~22 air","/summon pig ~1 ~-2 ~22","/clone ~4 ~4 ~1 ~6 ~7 ~3 ~ ~-3 ~25","/clone ~4 ~4 ~5 ~6 ~7 ~7 ~ ~-3 ~29","/fill ~1 ~-1 ~30 ~1 ~-2 ~30 air","/summon pig ~1 ~-2 ~30","/clone ~ ~4 ~1 ~2 ~7 ~3 ~ ~-3 ~33","/fill ~1 ~-1 ~34 ~1 ~-2 ~34 air","/summon pig ~1 ~-2 ~34","/clone ~ ~4 ~5 ~2 ~7 ~7 ~ ~-3 ~37","/clone ~ ~4 ~1 ~2 ~7 ~3 ~ ~-3 ~41","/clone ~ ~4 ~1 ~2 ~7 ~3 ~ ~-3 ~45","/fill ~1 ~-1 ~46 ~1 ~-2 ~46 air","/summon pig ~1 ~-2 ~46","/clone ~2 ~4 ~3 ~4 ~7 ~5 ~ ~-3 ~49","/clone ~2 ~4 ~3 ~4 ~7 ~5 ~ ~-3 ~53","/fill ~1 ~-1 ~54 ~1 ~-2 ~54 air","/summon pig ~1 ~-2 ~54","/clone ~3 ~4 ~10 ~5 ~7 ~14 ~ ~-3 ~57","/fill ~ ~4 ~ ~6 ~7 ~15 air"]}
As recommended by the challenge text, I got the latest Minecraft Java Launcher and launched a world:
I followed the YouTube video and gave myself a command block, placed it with a button on it, and posted the mc86 initcode:
I clicked the button and received an enchanted book:
I followed the instructions and clicked each of the six links to generate my mc86 computer in my world:
Next, following the YouTube video, I pasted the challenge source code into the command block I created earlier and click the button:
This gave me a 41 page book and quill:
I placed a button in the mc86 computer (as directed in the YouTube video) and and clicked it to run the challenge program:
This created a strange pattern of fence panels with pigs being in holes in some of the sections:
Here is a better view of the whole structure:
Based on the challenge name, I googled for ciphers containing symbols (looking for symbols similar to the fance panels). This led me to the pigpen cipher:
Being lazy, I go to my favorite cipher decoder website… dcode.fr:
I punch in the symbols found in my Minecraft world and click to decrypt it:
This gave me the flag:
UDCTF{LITERALPIGPENS}