Gawds CTF/ Know whats in your head

28 Jan 2018

Description

Try to see whats inside your head before moving forward.

https://head.ctf.gawds.in

This challenge was filled with dummy flags and was quite frustrating.

---

The Challenge

Looking at the description, it looks like the answer lies within the headers.

Like always, checking the robots.txt file, gave up the following info.

### BEGIN FILE ###

User-agent: gawds-crawler
Disallow:

### END FILE ###

From the robots.txt file, we can now infer that the User-Agent must be gawds-crawler.

Navigating to

http://swisshawk.ctf.gawds.in/flag

greets us with a Access Denied error.

Changing the method to POST also results in the same error.

I started to dig more.

I stumble upon sitemap.xml

This XML file does not appear to have any style information associated with it. The document tree is shown below.
<urlset xmlns="http://www.sitemaps.org/schemas/sitemap/0.9">
<url>
<loc>http://www.example.com/</loc>
<lastmod>2018-01-02</lastmod>
<changefreq>once</changefreq>
<priority>0.8</priority>
</url>
<url>
<loc>
http://www.example.com/53129cdb3222c675a3ab1d3763a7665e90e26aed
</loc>
<lastmod>2018-01-02</lastmod>
<changefreq>once</changefreq>
<priority>1.0</priority>
</url>
</urlset>

Visiting

https://head.ctf.gawds.in/53129cdb3222c675a3ab1d3763a7665e90e26aed

Checking the headers:

tryharderflag:flag{Alm0st_Reach4d_But_THis_is_A_DUmmY_Flag}

This was quite pissing off! I decided to give last and final shot.

Looking at the hash string, it seemed like a sha-1 hash.

So, I performed sha-1 hash of flag and obtained

112f3a99b283a4e1788dedd8e0e5d35375c33747

Visiting,

https://head.ctf.gawds.in/112f3a99b283a4e1788dedd8e0e5d35375c33747

You get:

When we check the headers, we get:

Flag: flag{G00d_W0rk_AlWys_check_f0R_headers}