Cicada 303.. Walkthrough

GCBQ90P - puzzle path and method

1. Start with the page clue

The cache description gives the main hint:

Hello. We are continuing looking for highly intelligent individuals.
This is our final test, it may impair your vision, just keep your eye on on the target.
Find it, and it will lead you on the road to finding us.
We look forward to meeting the few that will make it all the way through.

Good luck.
C303

The key phrase is: “it may impair your vision, just keep your eye on the target.” This points to a vision-based code and image-based steganography. The vision clue leads to Quadoo, a six-line symbol system intended for the visually impaired, and the target clue points to inspecting the Cicada image carefully for hidden data.

The page contains a long sequence made only from the digits 1 through 6, with 0 used as a separator. That points to Quadoo Code.

2. Decode the Quadoo Code

Use the full number sequence from the cache page in a Quadoo decoder, such as the Cachesleuth Quadoo tool.

1 1 1 1235 134 16 5 246 0 1245 134 36 36 25 16 134 1 1 1 35 5 35 25 235 25 125 12345 125 1 1 1
2345 34 12346 1235 56 234 1234 14 146 145 6 125 135 236 45 12346 123 24 56 1 1 1 125 12345 125
25 235 25 35 5 35 1 1 1 134 246 235 1245 134 36 36 25 16 134 1 1 1

The Quadoo decode gives:

---BEGIN
MESSAGE---CICADA303---WLQBXUOFRP/3ZYVQ2HX---303ADACIC---ENDMESSAGE---

The important middle string is:

WLQBXUOFRP/3ZYVQ2HX

3. Caesar shift the middle string

Apply a Caesar shift of -3 to the letters. The shifted result becomes a TinyURL-style link. Restore the URL punctuation and lowercase formatting.

WLQBXUOFRP/3ZYVQ2HX
Caesar -3:
TINYURLCOM/3WVSN2EU
Restored URL:
tinyurl.com/3wvsn2eu

4. The blank text file is not blank

The TinyURL resolves to a text file:

https://out14nd3r.com/wp-content/uploads/2026/05/cicada303.txt

The file appears blank, but the blank space is part of the puzzle. Copy the contents of the file, including the invisible whitespace. Go to Spam Mimic and use Decode → Decode Space. The decoded result is:

gvalhey.pbz/pvpnqn303

That result is ROT13. Decode it with ROT13:

gvalhey.pbz/pvpnqn303
ROT13:
tinyurl.com/cicada303

5. Follow the next link to the image

The ROT13 result leads to an image. Save the image for steganography analysis. The image title/filename contains the clue:

CICADA-G1-303.png

This tells you where to look: G1 means Green channel, bit plane 1. The 303 clue is used later for extraction.

6. Use StegOnline: Green 1

Upload the image to StegOnline:

https://www.georgeom.net/StegOnline/upload

Once uploaded, click Browse Bit Planes and go to Green 1. In the Green 1 bit plane, a hidden Braille image appears.

Translate the Braille. It gives:

13 S 517591.496

This is the first part of a UTM coordinate. Do not treat it as a standalone answer yet.

7. Use Extract Files/Data with the 303 clue

Return to the StegOnline tools and click Extract Files/Data. The image title contains 303, so select the RGB bit planes matching 303:

R = 3
G = 0
B = 3

Use these extraction settings:

Pixel Order: Row
Bit Order: MSB
Bit Plane Order: R G B
Trim Trailing Bits: No

Click Go. The result gives the second part of the UTM coordinate:

4369047.539

8. Combine and check

Combine the Braille result and the extracted data result to form one UTM coordinate:

13S 517591.496 4369047.539

Convert the UTM coordinate to decimal degrees or standard geocaching coordinate format. Enter the converted coordinates into the Certitude checker for GCBQ90P.

The final coordinates are intentionally not shown in this walkthrough.