Bandit: Level 8 - Level 9

Level 8

Username: bandit8
Password: dfwvzFQi4mU0wfNbFOe9RoWskMLg7eEc

Task:

https://overthewire.org/wargames/bandit/bandit9.html

The password for the next level is stored in the file data.txt and is the only line of text that occurs only once

Commands you may need to solve this level
grep, sort, uniq, strings, base64, tr, tar, gzip, bzip2, xxd

Start

Let’s begin by connecting to the server bandit.labs.overthewire.org and logging in with user bandit8 on port 2220.

We have several commands available for this task:

man (1)              - an interface to the system reference manuals
grep (1)             - print lines that match patterns
sort (1)             - sort lines of text files
uniq (1)             - report or omit repeated lines
strings (1)          - print the sequences of printable characters in files
base64 (1)           - base64 encode/decode data and print to standard output
tr (1)               - translate or delete characters
tar (1)              - an archiving utility
gzip (1)             - compress or expand files
bzip2 (1)            - a block-sorting file compressor, v1.0.8
xxd (1)              - make a hex dump or do the reverse.

Solve the level

Checking the commands above we need something to filter out a line of text which just appears once. :)

uniq and sort looking promising.

Lets check the manual entrys:

SORT(1)                                                                    User Commands                                                                   SORT(1)

NAME
       sort - sort lines of text files

SYNOPSIS
       sort [OPTION]... [FILE]...
       sort [OPTION]... --files0-from=F

DESCRIPTION
       Write sorted concatenation of all FILE(s) to standard output.

Okay so we can sort line of text files with sort. What about uniq?

   -u, --unique
              only print unique lines

Lets try to send the output from sort to uniq.

bandit8@bandit:~$ sort data.txt |uniq -u
4CKMh1JI91bUIZZPXDqGanal4xvAg0JM

Perfect! We got the password:

Password: 4CKMh1JI91bUIZZPXDqGanal4xvAg0JM

Explanation:

Understanding the uniq Command

The uniq command in Linux is used to process input by removing or filtering out duplicate lines. Here are some key features:

• Filter for Unique Lines: By default, uniq removes duplicate lines from the input, but with the -u flag, it can display only lines that occur exactly once.

• Count Occurrences: Using the -c option, uniq can prepend a count of occurrences to each line, showing how many times each line appears.

• Show Duplicates: The -d flag makes uniq output only the lines that are duplicated in the input.

Common Usage with sort

The uniq command is often used in conjunction with sort because uniq relies on the input being sorted to correctly identify duplicates.

• Sorting Lines: The sort command arranges lines of text in a specific order. It includes options for sorting in reverse (-r) or numerically (-n).

When you use sort followed by uniq, you ensure that all duplicate lines are adjacent, allowing uniq to effectively filter or count them.

Example:

```bash sort file.txt | uniq -c