Bazirovanaya baza (Based Base)

Platform: CUSTOM | Category: Crypto | Type: Challenge | Difficulty: Easy | OS: N/A | **Author: XESXOR Techniques: ascii_to_char, base32_decode, base64_decode

Summary

Walkthrough of the CUSTOM Crypto Bazirovanaya baza (Based Base). Task: decode a multi-layer encoded string from a file. Solution: sequentially decode Base64, Base32, and ASCII character codes to recover the flag.

Description

"Poreflesiruyem" (Let's reflect)

Files provided: crypt3.txt

Initial Analysis

The challenge name "Bazirovanaya baza" (Based base) is a strong hint that multiple base encodings are involved. The description "Poreflesiruyem" (Let's reflect) suggests we need to reverse/decode the encoding process.

The file crypt3.txt contains:

R1k0Q0FPQlZFQTNET0lCWEdVUURNT0pBSEFaQ0FPSlFFQVlURU1aQUdRNFNBTkpWRUE0VEtJQlVIRVFES01aQUhFMlNBT0pZRUEyVEVJQlZHTVFES01KQUdFWkRLPT09=

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This is clearly Base64 encoded (alphanumeric characters with = padding at the end).

Solution

Layer 1: Base64 Decode

 bash read-only • copy allowed Copy
echo "R1k0Q0FPQlZFQTNET0lCWEdVUURNT0pBSEFaQ0FPSlFFQVlURU1aQUdRNFNBTkpWRUE0VEtJQlVIRVFES01aQUhFMlNBT0pZRUEyVEVJQlZHTVFES01KQUdFWkRLPT09=" | base64 -d

Result:

GY4CAOBVEA3DOIBXGUQDMOJAHAZCAOJQEAYTEMZAGQ4SANJVEA4TKIBUHEQDKMZAHE2SAOJYEA2TEIBVGMQDKMJAGEZDK===

Layer 2: Base32 Decode

The output has characteristics of Base32 encoding:

• Uppercase letters A-Z
• Digits 2-7
• Padding with === ‍​‌‌​​‌​​​‌‌​​‌​​​​‌‌​‌​​​​‌‌‌​​‌​​‌‌​​​‌​​‌‌‌​​​​​‌‌​‌‌​​​‌‌​​​​‍

 python read-only • copy allowed Copy
import base64
result = base64.b32decode('GY4CAOBVEA3DOIBXGUQDMOJAHAZCAOJQEAYTEMZAGQ4SANJVEA4TKIBUHEQDKMZAHE2SAOJYEA2TEIBVGMQDKMJAGEZDK===')
print(result.decode())

Result:

68 85 67 75 69 82 90 123 49 55 95 49 53 95 98 52 53 51 125

Layer 3: ASCII Codes to Characters

The output is a series of space-separated decimal numbers - ASCII character codes!

 python read-only • copy allowed Copy
codes = '68 85 67 75 69 82 90 123 49 55 95 49 53 95 98 52 53 51 125'.split()
flag = ''.join(chr(int(c)) for c in codes)
print(flag)

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Result: DUCKERZ{REDACTED}

Complete Solution Script

 python read-only • copy allowed Copy
#!/usr/bin/env python3
"""
Duckerz CTF - Bazirovanaya baza (Based Base)
Multi-layer encoding: Base64 -> Base32 -> ASCII codes
"""
import base64

# Original encoded string from crypt3.txt
encoded = "R1k0Q0FPQlZFQTNET0lCWEdVUURNT0pBSEFaQ0FPSlFFQVlURU1aQUdRNFNBTkpWRUE0VEtJQlVIRVFES01aQUhFMlNBT0pZRUEyVEVJQlZHTVFES01KQUdFWkRLPT09="

# Layer 1: Base64 decode
layer1 = base64.b64decode(encoded).decode()
print(f"[+] After Base64: {layer1}")

# Layer 2: Base32 decode
layer2 = base64.b32decode(layer1).decode()
print(f"[+] After Base32: {layer2}")
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# Layer 3: ASCII codes to string
codes = layer2.split()
flag = ''.join(chr(int(c)) for c in codes)
print(f"[+] Flag: {flag}")

Meta Analysis

The flag 17_15_b453 is leetspeak wordplay:

• 17 = "IT"
• 15 = "IS"
• b453 = "BASE"

So the flag reads: "IT IS BASE" - a meta-reference to the multi-layer base encoding theme of the challenge!

Encoding Chain

Original: DUCKERZ{REDACTED}
    |
    v (ASCII codes)
68 85 67 75 69 82 90 123 49 55 95 49 53 95 98 52 53 51 125
    |
    v (Base32 encode)
GY4CAOBVEA3DOIBXGUQDMOJAHAZCAOJQEAYTEMZAGQ4SANJVEA4TKIBUHEQDKMZAHE2SAOJYEA2TEIBVGMQDKMJAGEZDK===
    |
    v (Base64 encode)
R1k0Q0FPQlZFQTNET0lCWEdVUURNT0pBSEFaQ0FPSlFFQVlURU1aQUdRNFNBTkpWRUE0VEtJQlVIRVFES01aQUhFMlNBT0pZRUEyVEVJQlZHTVFES01KQUdFWkRLPT09=

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Key Takeaways / Lessons

• Mastering ascii_to_char, base32_decode, base64_decode was key to this challenge.
• Always check for common misconfigurations and verify assumptions.

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Crafted by XESXOR Research • 2026-01-09 • CUSTOM • Bazirovanaya baza (Based Base) • Difficulty: Easy