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Author: Denarzai

_posts/2026-06-26-bandit-level-7-8.md

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+---
+title: "OverTheWire Bandit: Level 7 to Level 8"
+date: 2026-06-26 19:00:00 +0500
+categories: [CTF, Bandit]
+tags: [linux, grep, search, overthewire, beginner]
+---
+
+## The Goal
+
+Find the password stored in `data.txt` next to the word `millionth`.
+
+## What I Did
+
+Listed the directory to confirm the file:
+
+```bash
+bandit7@bandit:~$ ls
+data.txt
+```
+
+Tried reading it with `cat`:
+
+```bash
+bandit7@bandit:~$ cat data.txt
+```
+
+A massive wall of text came out — thousands of lines, each containing a word and what looked like a password. Reading through it manually wasn't an option.
+
+I needed to find the specific line containing `millionth`. That's exactly what `grep` is for:
+
+```bash
+bandit7@bandit:~$ grep "millionth" data.txt
+millionth	dfwvzFQi4mU0wfNbFOe9RoWskMLg7eEc
+```
+
+One line. The password is right there next to the word.
+
+## What grep Actually Does
+
+`grep` stands for **Global Regular Expression Print**. It reads through a file line by line, checks each line against a pattern you give it, and prints every line that matches.
+
+The basic syntax is:
+
+```bash
+grep "pattern" filename
+```
+
+It's case sensitive by default. `grep "Millionth"` would find nothing here because the word is lowercase. To make it case insensitive add `-i`:
+
+```bash
+grep -i "millionth" data.txt
+```
+
+Other useful flags:
+
+| Flag | What it does |
+|---|---|
+| `-i` | Case insensitive search |
+| `-n` | Show line numbers |
+| `-v` | Invert — show lines that do NOT match |
+| `-r` | Search recursively through directories |
+| `-c` | Count matching lines instead of printing them |
+| `-l` | Print only filenames that contain a match |
+
+## The Other Commands on This Level
+
+This level lists several commands I didn't need here but are worth understanding:
+
+**`sort`** — sorts lines alphabetically or numerically. Almost always paired with `uniq`.
+
+**`uniq`** — removes consecutive duplicate lines. `sort data.txt | uniq` is the standard combination for finding or removing duplicates.
+
+**`strings`** — extracts readable text from binary files. When `cat` gives you garbage characters, `strings` pulls out only the human-readable parts.
+
+**`base64`** — encodes or decodes base64 data. `base64 -d file` decodes it back to the original content.
+
+**`tr`** — translates or replaces characters. `tr 'A-Z' 'a-z'` converts uppercase to lowercase. `tr -d '\n'` removes all newline characters.
+
+**`tar`** — bundles multiple files into one archive. `tar -xf archive.tar` extracts it.
+
+**`gzip` / `bzip2`** — compression tools. `gzip -d file.gz` and `bzip2 -d file.bz2` decompress files.
+
+**`xxd`** — shows a hex dump of a file. Used when you need to inspect raw bytes — common in reverse engineering and forensics.
+
+**`|` (pipe)** — the most important operator in Linux. Takes the output of one command and feeds it as input to the next:
+```bash
+cat data.txt | grep "millionth"
+```
+This does exactly the same thing as `grep "millionth" data.txt` — two ways to get the same result. Pipes become essential when chaining multiple commands together.
+
+## What I Learned
+
+**`grep` is the go-to tool for searching inside files.** When a file is too large to read manually, grep finds exactly what you need instantly.
+
+**The pipe operator chains tools together.** Linux is built around small tools that each do one thing well. The power comes from combining them.
+
+**Reading a massive file with `cat` first** showed me what the structure looked like — word on the left, password on the right — which confirmed that `grep` was the right approach.
+
+## Commands Used
+
+| Command | What it did |
+|---|---|
+| `ls` | Confirmed `data.txt` exists |
+| `cat data.txt` | Showed the file structure — too large to read manually |
+| `grep "millionth" data.txt` | Found the exact line containing the password |