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Steganography

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Tabs&Spaces

A mysterious ZIP file containing a collection of images and a file has been discovered. The task is to retrieve the flag.
We’re given a zip file that contains a random python file and a ctf folder that contains a lot of jpg file.
Noticed that the name of the files have spaces before the number
I decided to rename the files so the name of the file can appear when I use the command ls since it’s related to steganography, I decided to check all the metadatas of the images and noticed that there’s a lot of png files that are using jpg extension but only one true jpg file, that is 87.jpg let’s try to find something using stegseek to 87.jpg

whitespace_flag.txt

After checking it out, apparently we can’t use stegsnow to solve it, but let’s try decoding it to binary where \t is 1 and ' ' is 0 command: cat whitespace_flag.txt | tr ' ' '0' | tr '\t' '1'
Output
Put it into cyberchef and we got the flag
Flag: ACECTF{n0_3xp1017_n0_g41n}

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Cryptic Pixels

This image looks normal at first, but something important is hidden inside. The secret is carefully concealed, making it hard to find. Your task is to explore the image, uncover the hidden message, and reveal what’s concealed. Do you have what it takes to crack the code and unlock the secret? Submit your answer in the following format: ACECTF{3x4mpl3\_fl4g}
We’re given a zip file containing an png image. Based on the description, there’s a couple methods we can use. The methods are using:
  • Stegseek/Steghide
  • Foremost/Binwalk
Since we didn’t get anything from using stegseek/steghide, let’s try using binwalk instead Command: binwalk CrypticPixels.png
Output
To extract a flag from a password-protected zip file, use zip2john to create a hash of the file, then use john to crack
John Command
Output
flag.txt
There are two possibilities: the flag is encoded using either ROT13 or ROT47. Let’s use CyberChef’s ROT13 Brute Force tool to identify the

ROT13 Bruteforce

and we get the flag at Amount = 17 Flag: ACECTF{h4h4_y0u'r3_5m4r7}

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Whispering Waves

Alex, a passionate linguist and culture enthusiast, frequently visits the website Francophonie.org to learn about the French-speaking world. Alex is known for their love of cryptography and steganography, often hiding messages in unsuspecting places.
We’re given a set of wordlist and zip file that is protected with a password. I suspect that the zip file can be cracked using the wordlist given by the challenge, and yes it can. the password is Vierges The zip contains a wav file. If we analyzed it using Sonic Visualizer and enable spectogram layer.
bottom means 0 and top means 1, collect all the data and if it is decoded using binary then we will get the flag Flag: ACECTF{53cur1n6w3b}

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OSINT

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The Mysterious Building

We’re given an image where it looks like some kind of building with a tower near it. we assume that it’s in India after checking the metadata of the image using exiftool.
Exiftool Output
My team member said that it’s the Pitampura TV Tower. After checking it using google maps, it’s right and the building should be near that tower. By using the logo on the building, we found the exact building

PP Trade Centre

and the name of the building is PP Trade Centre Flag: ACECTF{pp_trade_centre}
Last modified on September 29, 2026