Serious Task (Серьёзный таск)

Platform: hackerlab | Category: Misc | Type: Challenge | Difficulty: Medium | OS: Linux | Author: XESXOR | Date: 2025-12-26 | Status: Solved Techniques: game_resource_extraction, strings_analysis, zip_archive_detection

Summary

Серьёзный таск (Serious Task) — HackerLab

Description

Подарки хотят все. Ментал не исключение. Вот только его методы получения подарков опасны для всех. В этот раз его слуги украли одну из коробочек. В коробочке был флаг в виде строки в открытом виде. Просто строка. Может, даже Сэма звать не придётся...

Analysis

Hints in the description

1. "Ментал" (Mental) — the main villain in the Serious Sam game series
2. "Серьёзный таск" (Serious Task) — wordplay: "Serious task" = "Serious Sam"
3. "Сэма звать не придётся" (Won't need to call Sam) — direct reference to the game's protagonist ‍​‌‌​​‌​​​‌‌​​‌​​​​‌‌​‌​​​​‌‌‌​​‌​​‌‌​​​‌​​‌‌‌​​​​​‌‌​‌‌​​​‌‌​​​​‍

Task files

The serious_task.zip archive contains two files:

• zz2212426643864eb1.txt — metadata
• zz2212426643864eb1.gro — game resource

Analyzing the .txt file

TITLE=Patch 3_02_LandOfDamned Broken Spawner Fix
...
The flag next to the SBC cannons

Key information:

• This is a patch for the "Land of Damned" level from Serious Sam HD
• Hint: the flag is located next to the SBC cannons

Analyzing the .gro file

 bash read-only • copy allowed Copy
file zz2212426643864eb1.gro
# Identified as ZIP archive

.gro — Serious Sam game resource format (essentially a ZIP archive). ‍​‌‌​​‌​​​‌‌​​‌​​​​‌‌​‌​​​​‌‌‌​​‌​​‌‌​​​‌​​‌‌‌​​​​​‌‌​‌‌​​​‌‌​​​​‍

Solution

Step 1: Extracting the .gro archive

 bash read-only • copy allowed Copy
unzip zz2212426643864eb1.gro

Extracted structure:

Content/
└── SeriousSamHD/
    └── Levels/
        └── 03_Medieval/
            └── 3_02_LandOfDamned.wld

Step 2: Analyzing the .wld file

.wld — binary game level file. Using strings to search for text:

 bash read-only • copy allowed Copy
strings 3_02_LandOfDamned.wld | grep -i "CODEBY\|flag"

Step 3: Extracting the flag

The flag was found in the file with spaces between characters:

C    O    D    E    B    Y    {    w    0    w    _    s    2    i    1    o    u    S    _    t    2    x    T    u    r    e    }

‍​‌‌​​‌​​​‌‌​​‌​​​​‌‌​‌​​​​‌‌‌​​‌​​‌‌​​​‌​​‌‌‌​​​​​‌‌​‌‌​​​‌‌​​​​‍

Removing spaces:

 bash read-only • copy allowed Copy
echo "C    O    D    E    B    Y    {    w    0    w    _    s    2    i    1    o    u    S    _    t    2    x    T    u    r    e    }" | tr -d ' '

Flag breakdown

The flag in leet-speak: REDACTED = wow_seriouS_texture

• w0w → wow
• s2i1ouS → seriouS (2=r, 1=i)
• t2xTure → texture (2=e)

Useful commands

 bash read-only • copy allowed Copy
# Identify file type
file suspicious_file.gro

# Extract .gro as ZIP
unzip file.gro

# Search for strings in binary file
strings -n 5 level.wld | grep -i flag
‍​‌‌​​‌​​​‌‌​​‌​​​​‌‌​‌​​​​‌‌‌​​‌​​‌‌​​​‌​​‌‌‌​​​​​‌‌​‌‌​​​‌‌​​​​‍

# Search with context
strings level.wld | grep -B2 -A2 "CODEBY"

References

• Serious Sam Wiki
• GRO file format — similar format in other games ‍​‌‌​​‌​​​‌‌​​‌​​​​‌‌​‌​​​​‌‌‌​​‌​​‌‌​​​‌​​‌‌‌​​​​​‌‌​‌‌​​​‌‌​​​​‍