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PicoCTF - Search source

Posted Updated
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By Charalampos Spanias 2 min read

Description: The developer of this website mistakenly left an important artifact in the website source, can you find it?

Hint: How could you mirror the website on your local machine so you could use more powerful tools for searching?

  1. The website lands us on an interesting page:

  2. The tile of the challenge, Search source, points on viewing the page’s source code:

  3. After searching all JavaScript and many CSS files, we can find the flag at the style.css file:

Microsfot Edge alternative (faster)

  1. A quicker way to do this, using Microsoft Edge, is by searching all files via the Inspect functionality:

Website mirroring alternative (local)

  1. We can mirror the entire website locally by using the wget -m option:

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     # mirror the entire website
 $ wget -m http://saturn.picoctf.net:65086/
 --2023-12-30 14:23:21--  http://saturn.picoctf.net:65086/
 Resolving saturn.picoctf.net (saturn.picoctf.net)... 13.59.203.175
 Connecting to saturn.picoctf.net (saturn.picoctf.net)|13.59.203.175|:65086... connected.
 HTTP request sent, awaiting response... 200 OK
 Length: 15920 (16K) [text/html]
 Saving to: ‘saturn.picoctf.net:65086/index.html’

 saturn.picoctf.net:65086/index 100%[====================================================>]  15.55K  76.4KB/s    in 0.2s

 2023-12-30 14:23:21 (76.4 KB/s) - ‘saturn.picoctf.net:65086/index.html’ saved [15920/15920]

 Loading robots.txt; please ignore errors.
 --2023-12-30 14:23:21--  http://saturn.picoctf.net:65086/robots.txt
 Reusing existing connection to saturn.picoctf.net:65086.
 HTTP request sent, awaiting response... 404 Not Found
 2023-12-30 14:23:22 ERROR 404: Not Found.

 --2023-12-30 14:23:22--  http://saturn.picoctf.net:65086/css/bootstrap.min.css
 Reusing existing connection to saturn.picoctf.net:65086.
 HTTP request sent, awaiting response... 200 OK
 Length: 140421 (137K) [text/css]
 Saving to: ‘saturn.picoctf.net:65086/css/bootstrap.min.css’

 saturn.picoctf.net:65086/css/b 100%[====================================================>] 137.13K   277KB/s    in 0.5s

 2023-12-30 14:23:22 (277 KB/s) - ‘saturn.picoctf.net:65086/css/bootstrap.min.css’ saved [140421/140421]

 <SNIP>

 FINISHED --2023-12-30 14:23:36--
 Total wall clock time: 15s
 Downloaded: 20 files, 655K in 11s (61.5 KB/s)

  2. We can see at the end of the above output that it has downloaded 20 files in total. We can see their structure using the tree command:

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     ─$ tree
 .
 └── saturn.picoctf.net:65086
     ├── css
     │   ├── bootstrap.min.css
     │   ├── owl.carousel.min.css
     │   ├── responsive.css
     │   └── style.css
     ├── images
     │   ├── 1.png
     │   ├── 2.png
     │   ├── 3.png
     │   ├── banner.jpg
     │   ├── loading.gif
     │   ├── logo.png
     │   ├── mail_icon.png
     │   └── phone_icon.png
     ├── index.html
     └── js
         ├── bootstrap.bundle.min.js
         ├── custom.js
         ├── jquery-3.0.0.min.js
         ├── jquery.mCustomScrollbar.concat.min.js
         ├── jquery.min.js
         ├── owl.carousel.min.js
         └── popper.min.js

 5 directories, 20 files

  3. Now we can use grep recursively to search for the string of interest:

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     $ grep -R "picoCTF"
 saturn.picoctf.net:65086/css/style.css:/** banner_main picoCTF{1nsp3ti0n_0f_w3bpag3s_587d12b8} **/

Resources

CTF, Web
picoctf web web-exploitation search-source html css microsoft-edge
This post is licensed under CC BY 4.0 by the author.