Bandit Level 9: The Pattern Spotter (`grep` with a Twist)

(The short answer for this challenge is available at the end of this post.)

Introduction: The Password with a Flair for Drama

You’ve mastered finding unique lines with sort and uniq, and you’re already a grep wizard for simple word searches. But what if the password isn’t just a word, but a line marked by a very specific, almost theatrical, preamble? Welcome to Bandit Level 9, where the password proudly announces itself with a string of equal signs.

The level description for Bandit Level 9 states:

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

“Preceded by several ‘====’ characters.” This is a perfect job for grep, but we need to tell grep to look for lines that start with this specific pattern. It’s like finding a treasure chest that always has a big “X” painted directly on its lid.

Level 9: grep - The Pattern Matcher (Anchors Away!)

You’ve just logged in as bandit9 with the password from Level 8. A quick ls will confirm the target file:

ls

You’ll see:

data.txt

Again, if you cat data.txt, you’ll likely be overwhelmed by a lot of seemingly random text. We need to be more precise than a simple grep.

grep with Start-of-Line Matching (^)

You already know grep searches for patterns. What you might not know is that grep understands basic regular expressions. One of the most useful regular expression characters is the caret (^).

• ^: In grep, the caret means “the beginning of the line.”

So, if we want to find lines that start with “====”, we combine the caret with our pattern: ^====.

The command to find our password will be:

grep '^====' data.txt

Type this into your terminal and press Enter. grep will diligently scan data.txt and print out any lines that begin with four or more equal signs.

The output should be a single line, something like:

==== [THIS IS YOUR PASSWORD] ====

The string of characters between the ==== signs is your password for bandit10! Copy it down carefully.

Moving Onward:

Got that password? You’re a regex master in the making!

exit

And now, for the next challenge:

ssh [email protected] -p 2220

Enter your hard-won password, and you’re logged into bandit10. You’re getting dangerously good at this!

Conclusion: grep - Your Precision Tool

You’ve successfully conquered Bandit Level 9, refining your grep skills to pinpoint specific patterns:

• Using the ^ (caret) character to match patterns at the beginning of a line.
• Applying this knowledge to extract crucial information from noisy files.

Understanding basic regular expressions within grep (and other Linux tools) is a powerful skill for anyone working with text data. It allows for highly precise and efficient searches.

SPOILER ALERT: Short Answer for Bandit Level 9

1. Log in as bandit9.
2. Use grep to find the line starting with ====:
   grep '^====' data.txt

3. The output contains the password for bandit10.
4. Copy the password.

Ready for what Bandit Level 10 has in store?

Continue to Bandit Level 10!