NoMap3D — HackTheBox

Description

"I'm lost in this green cube hell. I have to find a way out of it."

Challenge provides an ELF 64-bit PIE executable (not stripped) — an SDL2 raycasting game in Wolfenstein 3D style, and an assets.dmp file (11.9 MB) containing map data, skybox, and textures. Unlike the related NoClip challenge which encoded the flag in individual character textures, NoMap3D encodes the flag as ASCII art formed by the wall layout itself.

Flag format: HTB{...}

Analysis

Step 1: Initial Recon

file nomap3d
# ELF 64-bit LSB pie executable, x86-64, not stripped, dynamically linked

nm nomap3d | grep -E "player|raycast|colf|window|event|asset"
# load_assets, player_init, raycast, event, input
# colf.c, window.c, event.c, player.c, raycast.c

The binary uses the same SDL2 raycasting engine as the NoClip challenge. Key modules: collision detection (colf.c), player control (player.c), raycasting renderer (raycast.c), input handling (event.c), SDL2 window (window.c).

The name "NoMap3D" is a direct hint: "No Map" → the flag says "Who needs a map" in leetspeak. The map layout itself IS the flag.

Step 2: Parsing assets.dmp

The file uses the same chunk-based format as NoClip:

Chunk 1 (id=1): Player position

Offset	Type	Value	Description
0x00	uint32	1	Chunk ID
0x04	double	103.0	Player X position
0x0C	double	7.0	Player Y position

Chunk 2 (id=2): Map data

Offset	Type	Value	Description
0x14	uint32	2	Chunk ID
0x18	uint32	259	Map width
0x1C	uint32	12	Map height
0x20	byte[]	259×12×3	Map data (9324 bytes)

Each map cell is 3 bytes (column-major order: map[x * height + y]):

• Byte 0: Wall type — 0=empty, 1=standard wall, 2=wall_circuit texture
• Byte 1: Side texture index (unused)
• Byte 2: Floor texture — 2=floor, 3=arrow up

Chunk 3 (id=3): Skybox texture

• Name: "skybox", 1024×906 RGBA

Chunk 4 (id=4): Textures — Only 3 generic textures:

Index	Name	Size	Purpose
0	htb	128×128	HTB logo
1	wall_circuit	1024×985	Wall texture
2	floor_circuit	1024×997	Floor texture

Step 3: Key Insight — Map IS the Flag

Unlike NoClip (which had 18 textures including individual character textures), NoMap3D has only 3 generic textures. The flag is encoded differently: the wall layout itself forms ASCII art text.

The map is 259 columns × 12 rows — a wide horizontal banner. The outer border (y=0, y=11, x=0, x=258) is all wall_circuit walls. The inner area (y=1 to y=10) contains the flag text formed by standard walls (wall_type=1).

All floor tiles have arrow-up texture (floor_tex=3), meaning the player looks upward at the walls — a hint to visualize the map from above.

Step 4: Extracting the ASCII Art

Extracting the wall pattern for y=2 to y=8 (the 7-row letter area) reveals clear ASCII art characters:

 #####   ##### ############# ##########     ###  ######   ######     #### ####           ####                               ####       ####    ##########      #######                      #                    ###        #####        #               ###     
  ###     ###  #    ###    #  ###     ###  ##      ###      ###       #    ###         ##   ###                           ########   ########   ###     ###  ###     ###                   ###                    ##         ###       ###                 ##    
  ###     ###       ###       ###     ###  #        ###     ####     #     ###  ##    ##   ## ##             ###   ##           ##         ##   ###      ### #####                        #####                   ####     # ###     # ###   ## #####       #    
  ###########       ###       ##########  ##         ###   #  ###   #      #########  ##  ##  ##              #########      ####       ####    ###      ###   #######                   #   ###                  # ###   #  ###   #   ###    ###   ###     ##   
  ###     ###       ###       ###     ###  #          ### #    ### #       ###   ###  ## ##   ##              ###   ###        ###        ###   ###      ###       #####                #########                 #   ###    ###  ##########  ###   ###     #    
  ###     ###       ###       ###     ###  ##          ###      ###        ###   ###   ###   ##               ###   ###  #     ###  #     ###   ###     ###  ##      ###               #       ###                #    #     ###       ###    ###   ###    ##    
 #####   #####     #####     ##########     ###         #        #        ##### #####   ######   ########### ##### #####  ######     ######    ##########    #########   ########### ####     ###### ########### ###        #####     #####   ########   ###     

Step 5: Reading the Characters

Segmenting by all-space columns yields 20 character segments. Reading left to right:

Seg	Character	Notes
0	H	Two vertical bars, horizontal middle
1	T	Full top bar, vertical center
2	B	Left bar with right bumps
3	{	Opening brace
4	W	Two V-shapes
5	h	Lowercase: left bar full height, right starts mid
6	0	Oval with diagonal
7	_	Only bottom row
8	n	Lowercase: only bottom 5 rows, arch shape
9	3	Right-facing curves
10	3	Same as seg 9
11	D	Left bar, right curve
12	S	S-curves
13	_	Only bottom row
14	A	Triangle/pyramid
15	_	Only bottom row
16	M	Left bar with right diagonals
17	4	Vertical with crossbar
18	p	Lowercase with descender to y=9,10
19	}	Closing brace

Solution

#!/usr/bin/env python3
"""
HTB Challenge: NoMap3D (GamePwn)
Solution: Extract flag from SDL2 raycasting game assets

The game uses the same engine as NoClip, but the flag is encoded differently.
Instead of character textures on special walls, the flag is ASCII art formed
by the wall layout itself. The map is 259x12 - a wide horizontal banner.

The "NoMap" name hints that the map IS the flag: "Who needs a map" in leetspeak.
"""

import struct


def solve():
    with open("assets.dmp", "rb") as f:
        data = f.read()

    offset = 0

    # Chunk 1: Player position
    chunk_id = struct.unpack_from("<I", data, offset)[0]
    assert chunk_id == 1
    offset += 4
    player_x, player_y = struct.unpack_from("<dd", data, offset)
    offset += 16
    print(f"Player start: ({player_x}, {player_y})")

    # Chunk 2: Map data
    chunk_id = struct.unpack_from("<I", data, offset)[0]
    assert chunk_id == 2
    offset += 4
    map_width, map_height = struct.unpack_from("<II", data, offset)
    offset += 8
    print(f"Map size: {map_width}x{map_height}")

    # Map is stored column-major: map[x * height + y] with 3 bytes per cell
    # Byte 0: wall type (0=empty, 1=standard wall, 2=wall_circuit)
    # Byte 1: side texture index (unused)
    # Byte 2: floor texture (2=floor, 3=arrow up)
    map_data = data[offset:offset + map_width * map_height * 3]

    # Extract wall pattern as ASCII art (y=2 to y=8 is the main letter area)
    print("\n=== ASCII Art Wall Pattern ===\n")
    for y in range(2, 9):
        row = ""
        for x in range(1, map_width - 1):
            idx = (x * map_height + y) * 3
            wall_type = map_data[idx]
            row += "#" if wall_type >= 1 else " "
        print(row)

    # The pattern clearly shows: HTB{REDACTED}
    flag = "HTB{REDACTED}"
    print(f"\n{'=' * 50}")
    print(f"FLAG: {flag}")
    print(f"{'=' * 50}")
    return flag


if __name__ == "__main__":
    solve()

Related Challenges

• NoClip (HackTheBox, GamePwn, medium) — Same SDL2 raycasting engine, but flag encoded in individual character textures on special walls along a spiral maze path
• NoRadar (HackTheBox, GamePwn) — Same raycaster engine, flag encoded in entity waypoint trajectory in .rodata
• CubeMadness1 (HackTheBox, GamePwn, easy) — Unity game with hidden flag in textures