Update system-exploration directory

Transitioned the 'system-exploration' directory to meet the requirements of
the OpenEdu Methodology.

Signed-off-by: Sorin Birchi <sb.birchi.sorin@gmail.com>

Author: Sorin Birchi

chapters/scratch-linux/system-exploration/drills/tasks/doge/README.md

@@ -0,0 +1,32 @@
+# Doge
+
+The best way to showcase the `strings` command is to use it in order to find our first flag for today.
+Head to the `tasks/doge/support` folder and take a look at the image you've been given.
+
+Since this section is dedicated to the `strings` command, we'll run this command on our `doge.jpg` file:
+```
+root@kali:~/essentials/system-exploration/activities/doge/public# strings doge.jpg
+JFIF
+[...]
+eP!_"
+```
+
+So there are lots of human-readable strings in this image, but very few, if any, actually make any sense.
+In order to filter them out, we'll use what we've learned today: `|` + `grep`.
+We'll try to find the flag itself.
+Maybe we get lucky.
+```
+root@kali:~/essentials/system-exploration/activities/doge/public# strings doge.jpg | grep SSS
+<there should be a flag here>
+```
+
+That's how you use `strings`: often in combination with some filtering mechanism, such as `grep`.
+
+Another way to get the flag is to run the `file` command:
+```
+root@kali:~/essentials/system-exploration# file activities/doge/public/doge.jpg
+activities/doge/public/doge.jpg: JPEG image data, JFIF standard 1.01, aspect ratio, density 1x1, segment length 16, comment: "SSS{grep_your_strings}", progressive, precision 8, 500x500, components 3
+```
+The flag is included in the file as a comment.
+Image comments are often used in CTFs in order to hide some more subtle information, such as hints.
+Always remember to check them out.

chapters/scratch-linux/system-exploration/drills/doge/sol/solution.sh chapters/scratch-linux/system-exploration/drills/tasks/doge/solution/solution.sh

@@ -0,0 +1,6 @@
+# Empty Files
+
+So many empty files...
+Nevertheless, you must find the flag!
+
+If you're having difficulties solving this exercise, go through [this](/chapters/scratch-linux/system-exploration/reading/README.md##Sumary) reading material.

chapters/scratch-linux/system-exploration/drills/doge/public/doge.jpg chapters/scratch-linux/system-exploration/drills/tasks/doge/support/doge.jpg

@@ -0,0 +1,7 @@
+# Find Us If You Can
+
+This is a two-stage challenge.
+The first flag is somewhere on the remote system.
+Use the hint it comes with, in order to figure out the second flag as well.
+
+If you're having difficulties solving this exercise, go through [this](/chapters/scratch-linux/system-exploration/reading/README.md##Sumary) reading material.

chapters/scratch-linux/system-exploration/drills/tasks/empty-files/README.md

@@ -0,0 +1,8 @@
+# Not Your Doge
+
+The image is in `.pnm` format.
+It has a rather simple header, that you can find [here](https://en.wikipedia.org/wiki/Netpbm#PPM_example)(`.pnm`s are almost the same as `.ppm`s; it's just the data encoding that differs).
+But it's incomplete.
+Find a way to reveal it completely.
+
+If you're having difficulties solving this exercise, go through [this](/chapters/scratch-linux/system-exploration/reading/README.md##Sumary) reading material.

chapters/scratch-linux/system-exploration/drills/empty-files/sol/solution.sh chapters/scratch-linux/system-exploration/drills/tasks/empty-files/solution/solution.sh

@@ -0,0 +1,13 @@
+# Surgical Precision
+
+There are many false flags out there.
+Answer the questions and find the **real** flags.
+The quizzes cover subjects discussed today and during the previous session.
+Think of them as a recap.
+
+The answer to each of the riddles in the files `question-*` from the `activities/surgical-precision/public` is the name of one of the given files.
+When you've found an answer, upload the flag in that file.
+
+Beware of [red herrings](https://en.wikipedia.org/wiki/Red_herring)!
+
+If you're having difficulties solving this exercise, go through [this](/chapters/scratch-linux/system-exploration/reading/README.md) reading material.

chapters/scratch-linux/system-exploration/drills/tasks/find-us-if-you-can/README.md

@@ -109,9 +109,9 @@ From them and from the commands general description at the beginning of the `man
 root@kali:~# find <where to look> <what to look for>
 ```
 
-- `<where to look>` is quite self-explanatory: it's a path in the file system, from where `find` will start to look for what whe told it.
+- `<where to look>` is quite self-explanatory: it's a path in the file system, from where `find` will start to look for what we told it.
 This means that `find` traverse the file system _down_ from the path it's given by looking exhaustively into each of its directories.
-- `<what to look for>` is where things get more intersting.
+- `<what to look for>` is where things get more interesting.
 We've already said that we can look for files that match certain properties, such as names, permissions, sizes, types and so on.
 Each of these properties can be specified as follows:
 
@@ -211,7 +211,7 @@ However, `+` needs at least one character in order to match the specific string.
 Let's look at the following range: `[a-f]`.
 It starts at `a` and ends with `f`, inclusively.
 `[0-9]`, for example, matches any digit.
-Likewise, `[A-Z]` matches any capital leter, and so on.
+Likewise, `[A-Z]` matches any capital letter, and so on.
 
 You can combine ranges.
 For instance, `[a-zA-Z]` matches any letter.
@@ -501,7 +501,7 @@ Use `less`!
 
 ### Grep
 
-`find` has taught us how to use various criteria in order to filter throigh a file hierarhcy.
+`find` has taught us how to use various criteria in order to filter through a file hierarchy.
 This is definitely useful, but we can do better.
 `find` is highly capable of filtering output based on the files' **metadata**, i.e. "surface level" information, such as sizes, names and so on.
 
@@ -545,7 +545,7 @@ Now that we can find our way inside a file hierarchy, we need a means by which t
 `grep` works just fine, provided we're dealing with text files.
 But what if we aren't?
 
-In this case, we'll need to taka a sneak peak into some _binary analysis_.
+In this case, we'll need to take a sneak peak into some _binary analysis_.
 We'll get back to this subject starting from from Session [Data Representation](../data-representation).
 
 ### `file`
@@ -568,39 +568,6 @@ activities/05-challenge_not-your-doge/public/not-doge.pnm: Netpbm image data, si
 One of the most basic forms of binary analysis is to simply look for any human-readable string present in a binary file.
 For this purpose, we'll use the `strings` command.
 
-#### Tutorial: Doge
-
-The best way to showcase the `strings` command is to use it in order to find our first flag for today.
-Head to the `activities/doge/public` folder and take a look at the image you've been given.
-
-Since this section is dedicated to the `strings` command, we'll run this command on our `doge.jpg` file:
-```
-root@kali:~/essentials/system-exploration/activities/doge/public# strings doge.jpg
-JFIF
-[...]
-eP!_"
-```
-
-So there are lots of human-readable strings in this image, but very few, if any, actually make any sense.
-In order to filter them out, we'll use what we've learned today: `|` + `grep`.
-We'll try to find the flag itself.
-Maybe we get lucky.
-```
-root@kali:~/essentials/system-exploration/activities/doge/public# strings doge.jpg | grep SSS
-<there should be a flag here>
-```
-
-That's how you use `strings`: often in combination with some filtering mechanism, such as `grep`.
-
-Another way to get the flag is to run the `file` command:
-```
-root@kali:~/essentials/system-exploration# file activities/doge/public/doge.jpg 
-activities/doge/public/doge.jpg: JPEG image data, JFIF standard 1.01, aspect ratio, density 1x1, segment length 16, comment: "SSS{grep_your_strings}", progressive, precision 8, 500x500, components 3
-```
-The flag is included in the file as a comment.
-Image comments are often used in CTFs in order to hide some more subtle information, such as hints.
-Always remember to check them out.
-
 ## Summary
 
 Here are a few useful snippets from today's session:
@@ -609,38 +576,6 @@ Here are a few useful snippets from today's session:
 - `cat large_file | grep SSS`: looks for the `SSS` string in a large file, so you don't have to do this manually;
 - `find some/path <some criteria> | xargs grep SSS`: look for the `SSS` string in each file that matches some specified criteria.
 
-## Activities
-
-### Challenge: Surgical Precision
-
-There are many false flags out there.
-Answer the questions and find the **real** flags.
-The quizzes cover subjects discussed today and during the previous session.
-Think of them as a recap.
-
-The answer to each of the riddles in the files `question-*` from the `activities/surgical-precision/public` is the name of one of the given files.
-When you've found an answer, upload the flag in that file.
-
-Beware of [red herrings](https://en.wikipedia.org/wiki/Red_herring)!
-
-### Challenge: Empty Files
-
-So many empty files...
-Nevertheless, you must find the flag!
-
-### Challenge: Find Us If You Can
-
-This is a two-stage challenge.
-The first flag is somewhere on the remote system.
-Use the hint it comes with, in order to figure out the second flag as well.
-
-### Challenge: Not Your Doge
-
-The image is in `.pnm` format.
-It has a rather simple header, that you can find [here](https://en.wikipedia.org/wiki/Netpbm#PPM_example)(`.pnm`s are almost the same as `.ppm`s; it's just the data encoding that differs).
-But it's incomplete.
-Find a way to reveal it completely.
-
 ## Further Reading
 
 ## Forensics

chapters/scratch-linux/system-exploration/drills/find-us-if-you-can/sol/solution.sh chapters/scratch-linux/system-exploration/drills/tasks/find-us-if-you-can/solution/solution.sh

@@ -66,6 +66,17 @@ docusaurus:
               path: chapters/scratch-linux/system-exploration/
               subsections:
                 - Reading: reading/README.md
+                - Drills:
+                    path: drills/
+                    subsections:
+                      - Tasks:
+                          path: tasks/
+                          subsections:
+                          - Doge/: doge/README.md
+                          - Empty Files/: empty-files/README.md
+                          - Find us if you can/: find-us-if-you-can/README.md
+                          - Not your doge/: not-your-doge/README.md
+                          - Surgical precision/: surgical-precision/README.md
       - Demystifying the Web:
           - Overview: chapters/demystifying-web/overview/README.md
           - Explaining the Internet: