Corrupted File ~ Traboda Forensic Challenge Write up

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Challenge Description : Reshma thinks there is some issue with this file. Can you help Reshma in fixing the issue with this file?

Flag Format : flag{some_l33t_string}

Challenge Link : https://app.traboda.com/challenge/148

We are given a zip folder named chall. At first we wont be able to extract/view the contents in this zip folder. To fix this issue and get more information about this folder we will be using a tool named GHex which helps us to view and edit the hex data or hex dump of an image/data.We can also see the headers, footers, and the data chunks of a data.

We can use this tool by using the command

ghex flag.zip 

On executing this command , we shall the following window on our screen

In the Right column , we can see a text

Here is the secret information: ZmxhZ3s5ZTM2MDA4NDE5NmEwOTJhMTVjNWM0NGI1NDkzNGJmY30=

We can say that the 2nd part of the above string is a base64 string , which can be decoded through

echo 'ZmxhZ3s5ZTM2MDA4NDE5NmEwOTJhMTVjNWM0NGI1NDkzNGJmY30=' | 
base64 --decode

The Required flag is flag{9e360084196a092a15c5c44b54934bfc}

Additional Installation

1. GHex

$ sudo apt install ghex