BackdoorCTF 2016 - intro16

BackdoorCTF is the annual flagship CTF competition conducted by SDSLabs and InfoSecIITR.

Challenge: Get the first part of the flag from IRC freenode (#backdoorctf) and the second part from twitter(@BackdoorCTF)

Write-up

As the description says I got the first part of the flag from IRC(#backdoorctf) -> NWQ1bDRiNV9iNG

The second part of the flag from twitter(@BackdoorCTF) -> NrZDAwcmM3ZjIwMTY=

Joining this we get a base64 encoded string -> NWQ1bDRiNV9iNGNrZDAwcmM3ZjIwMTY=

Decoding this and taking its SHA256 hash we get our solution.

echo -n NWQ1bDRiNV9iNGNrZDAwcmM3ZjIwMTY= | base64 --decode | shasum -a 256

Note that I added -n for echo to prevent an extra newline being appended at the end, which will change the SHA256 checksum.