Skip to content

Bandit17->18

Level Goal

There are 2 files in the homedirectory: passwords.old and passwords.new. The password for the next level is in passwords.new and is the only line that has been changed between passwords.old and passwords.new.

NOTE: if you have solved this level and see ‘Byebye!’ when trying to log into bandit18, this is related to the next level, bandit19.

Commands useful to solve the level

Helpful Reading Material

Where to start?

We know that there are two files in our directory that we can view with the ls command : passwords.old and passwords.new, we are going to need to output the difference between those two files. We know that the new password is the line that has been updated in the passwords.new file.

Part 1 : Output the diff of the files

We want to see the differences between both files printed to standard output.

Hint

By looking at the diff man page, can you figure out how to use the diff(1) utility to output the differences between these two files?

Solution

To do so, we simply need to run the following command : 

diff passwords.old passwords.new
The lines that are different in passwords.old (the first argument) will appear prefixed by the symbol < while the lines different in passwords.new will appear prefixed by a >. The password is the line that is different in passwords.new

Part 2 : Making diff output a bit more readable

Right now, we need to remember that the different lines from the first file will be prefixed by < and the ones from the second file by >. Let's find a way to make the output more readable so that we don't need to remember this information.

Hint

Looking more deeply into the diff man page, can you figure out a way to make the output more readable ?

They are a lot more than one answer.

Solution

For example, one could use the option -u to print a string at the beginning of the diff output which will look like the one below : 

--- passwords.old   2023-10-05 06:19:27.827277353 +0000
+++ passwords.new   2023-10-05 06:19:27.835277371 +0000
which means that all the lines from passwords.old will be prefixed by - and the lines from passwords.new will be prefixed by +. The diff -u output will be the following : 
--- passwords.old   2023-10-05 06:19:27.827277353 +0000
+++ passwords.new   2023-10-05 06:19:27.835277371 +0000
@@ -39,7 +39,7 @@
 WFB9ezoSnb146RUbbX6d9Yx2sU46Q8Ax
 JFkUvvpfLmE7KBkAEePwZndBr33oFzh8
 wDn38KGxWKk7dp39odF7fWLT6aljqEsK
-old_password
+new_password
 RKMlN2JZydt4j5rQjJt07GgNqtgnq8dw
 nssByafsRMwebfyRhMWKSqX39xF1l4Hr
 ZlUzDUTd4faumV8wCtJ4CHA788tySKDO
We can then use the new password to go to the following level.

Full Solution
  1. diff passwords.old passwords.new to output the differences between the two files and retrieve the new password from the passwords.new file.

You can now jump to the next level