Bandit9->10

Level Goal

The password for the next level is stored in the file data.txt in one of the few human-readable strings, preceded by several ‘=’ characters.

Commands useful to solve the level

Helpful Reading Material

Strings Utility

Where to start?

As with the two previous levels, we are going to start by running file on our data.txt file.
Here is the output from this command :

bandit9@bandit:~$ file data.txt 
data.txt: data
bandit9@bandit:~$

We can now see that we are not dealing with a text file anymore, thus meaning that we can't use the utilities we're used to to retrieve our password.

Part 1 : Printing human-readable strings

To safely print human-readable strings in non text files, we can use the strings command. We need to figure out how to use this command to print the few human-readle strings in data.txt

Hint

Try to look in the strings(1) man page and find out how to use the strings utility to achieve this goal

Solution

We can use the --all option to ensure that all the file is scanned (this should be the default behavior but under certain implementations, the default behavior could be different so this will prevent the exploitation of any BFD library vulnerabilities).
Thus, the command we're looking for is strings --all data.txt, which will dump the human-readable strings to stdout.
Now, we just need to grep the character '=' in this output and look for the password string.

Full Solution

Here is the full command :

strings --all data.txt | grep =

We then need to look for the string that looks the most like what could be a password string, preceded by several '=' characters

Bonus : Using the size of the password string

We know that the password string is a 33 characters long string, so we know that the line we're looking for is at least 33 characters long. We are going to find a way to display only the (at least) 33 characters long strings in data.txt.

Hint

Reading the strings(1) man page, can you figure out an option to achieve this goal?

Solution

The option we're looking for is the -n option, we'll call it with -33 which means that we're looking for at least 33 characters long strings.

Here is the full command :

strings --all -33 data.txt

This command prints only one line, which contains the password we're looking for.

You can now jump to the next level