184 lines
5.3 KiB
Org Mode
184 lines
5.3 KiB
Org Mode
|
#+title: Readme
|
||
|
#+author: Phil Bajsicki
|
||
|
#+options: finline toc:nil
|
||
|
|
||
|
* Intro
|
||
|
This is a coding task from [redacted], which I found
|
||
|
rather fun to tinker with.
|
||
|
|
||
|
This is an org-mode file. The code blocks are tangled using =org-babel= into =cl-secninja.lisp=.
|
||
|
|
||
|
* Dependencies:
|
||
|
- curl
|
||
|
- sbcl with quicklisp
|
||
|
* Usage:
|
||
|
1. Load in SBCL with ~sbcl --load cl-secninja.lisp~.
|
||
|
2. Run ~(four)~
|
||
|
3. Copy the base64 encrypted message into a file called =email=.
|
||
|
4. Run ~(base64)~.
|
||
|
5. Done.
|
||
|
* Code:
|
||
|
** Quicklisp:
|
||
|
#+begin_src lisp :tangle cl-secninja.lisp
|
||
|
(ql:quickload '(:cl-ppcre
|
||
|
:cl-base64
|
||
|
:ironclad
|
||
|
:jsown))
|
||
|
#+end_src
|
||
|
|
||
|
** Defpackage and in-package
|
||
|
#+begin_src lisp :tangle cl-secninja.lisp
|
||
|
(defpackage #:cl-secninja
|
||
|
(:use #:common-lisp #:cl #:uiop #:cl-ppcre #:ironclad #:cl-base64))
|
||
|
|
||
|
(in-package #:cl-secninja)
|
||
|
#+end_src
|
||
|
|
||
|
** URL var
|
||
|
The trailing slash is important for consolidating the URL later.
|
||
|
#+begin_src lisp :tangle cl-secninja.lisp
|
||
|
(defvar *url* "redacted")
|
||
|
#+end_src
|
||
|
** Run cURL
|
||
|
#+begin_src lisp :tangle cl-secninja.lisp
|
||
|
(defun run-curl (command)
|
||
|
(let* ((curl-command (concatenate 'string "curl -i " command))
|
||
|
(result (uiop:run-program curl-command
|
||
|
:output :string
|
||
|
:error-output T)))
|
||
|
result))
|
||
|
|
||
|
#+end_src
|
||
|
|
||
|
** First page
|
||
|
Grab first page, print out the command and result, and return the parameter string.
|
||
|
#+begin_src lisp :tangle cl-secninja.lisp
|
||
|
(defun one ()
|
||
|
(let* ((command *url*)
|
||
|
(result (run-curl *url*)))
|
||
|
(format t "~%COMMAND: curl ~a" command)
|
||
|
(format t "~%RESULT: curl ~a" result)
|
||
|
(car (ppcre:all-matches-as-strings "\\?.*" result))))
|
||
|
#+end_src
|
||
|
** Second page
|
||
|
This function calls ~(one)~, so calling it directly for seeing the second page
|
||
|
works.
|
||
|
|
||
|
Concatenate the URL with the parameter string from the first function, and grab
|
||
|
and return the second page.
|
||
|
|
||
|
#+begin_src lisp :tangle cl-secninja.lisp
|
||
|
(defun two ()
|
||
|
(let* ((command (concatenate 'string
|
||
|
"\"" *url* (one) "\""))
|
||
|
(result (run-curl command)))
|
||
|
result))
|
||
|
#+end_src
|
||
|
** Third
|
||
|
This is where we get interesting. This function calls ~(two)~, which returns the
|
||
|
second page for processing, and then calls ~(run-curl)~ on the command it
|
||
|
constructs, and returns the output.
|
||
|
|
||
|
|
||
|
I wanted to see what the values of the variables are while testing, thus the
|
||
|
print statements and triple let. I know I could consolidate that, but I feel
|
||
|
like this way is more transparent than having a ~(let* (...))~ that does
|
||
|
everything in the background.
|
||
|
|
||
|
The thing that was most tricky here was getting the double quotes to work
|
||
|
properly between this function and ~(run-curl)~, because the =command= string is
|
||
|
being passed around, and it itself includes quotes.
|
||
|
|
||
|
|
||
|
|
||
|
#+begin_src lisp :tangle cl-secninja.lisp
|
||
|
(defun three ()
|
||
|
(let ((headers (ppcre:all-matches-as-strings "X-.*" (two))))
|
||
|
(print headers)
|
||
|
(print (car headers))
|
||
|
(print (cadr headers))
|
||
|
(let ((command (concatenate 'string
|
||
|
"\"" *url* "\?step=2" "\""
|
||
|
" -H \"" (car headers) "\""
|
||
|
" -H \"" (cadr headers) "\"")))
|
||
|
(let ((result (run-curl command)))
|
||
|
(format t "~%RESULT: curl ~a" result)
|
||
|
result))))
|
||
|
|
||
|
#+end_src
|
||
|
** Four
|
||
|
This was the most fun one, given all the processing. I can't say that the loop
|
||
|
worked the first time around.
|
||
|
|
||
|
After running ~(four)~, your terminal will print out the base64 encoded string.
|
||
|
I can't say I want to mess with extracting the base64 string with another
|
||
|
regexp, so I just manually copied the string into a file called =email=.
|
||
|
|
||
|
Then...
|
||
|
|
||
|
#+begin_src lisp :tangle cl-secninja.lisp
|
||
|
|
||
|
(defun four ()
|
||
|
(let*
|
||
|
((data (three))
|
||
|
(input
|
||
|
(car (ppcre:all-matches-as-strings "(?sm)\{.*}$" data)))
|
||
|
(challenge
|
||
|
(string-left-trim "challenge: " (car (ppcre:all-matches-as-strings "challenge:(.*)" data))))
|
||
|
(timestamp
|
||
|
(string-left-trim "timestamp: " (car (ppcre:all-matches-as-strings "timestamp:(.*)" data))))
|
||
|
(sorted (sort (cdr (jsown:parse input)) #'string<= :key #'first))
|
||
|
(connected
|
||
|
(string-right-trim "\&"
|
||
|
(format nil "~{~A~}"
|
||
|
(loop
|
||
|
for item in sorted
|
||
|
collect
|
||
|
(concatenate 'string (car item) "\=" (cdr item) "\&")))))
|
||
|
(hash (sha-256 connected))
|
||
|
(command
|
||
|
(string-right-trim "\-"
|
||
|
(concatenate 'string
|
||
|
"-X POST \"" *url* "\?step=3" "\""
|
||
|
" -H \"Content-Type: application/x-www-form-urlencoded\" "
|
||
|
" -d \"challenge=" challenge "\""
|
||
|
" -d \"timestamp=" timestamp "\""
|
||
|
" -d \"hash=" hash "\""
|
||
|
))))
|
||
|
(terpri)
|
||
|
(print challenge)
|
||
|
(print timestamp)
|
||
|
(print hash)
|
||
|
(terpri)
|
||
|
(format t "~%COMMAND: curl ~a" command)
|
||
|
(terpri)
|
||
|
(let ((result (run-curl command)))
|
||
|
(format t "~%RESULT: curl ~a" result))
|
||
|
(terpri)))
|
||
|
|
||
|
#+end_src
|
||
|
|
||
|
*** Sha256
|
||
|
Util function for the above code.
|
||
|
#+begin_src lisp :tangle cl-secninja.lisp
|
||
|
(defun sha-256 (str)
|
||
|
(ironclad:byte-array-to-hex-string
|
||
|
(ironclad:digest-sequence :sha256
|
||
|
(ironclad:ascii-string-to-byte-array str))))
|
||
|
|
||
|
#+end_src
|
||
|
** Base64
|
||
|
Put the contents of the file into a variable.
|
||
|
#+begin_src lisp :tangle cl-secninja.lisp
|
||
|
(defvar *email* (alexandria:read-file-into-string "email"))
|
||
|
#+end_src
|
||
|
Then, run the base64 decoder over it until the string can't be decoded any more.
|
||
|
#+begin_src lisp :tangle cl-secninja.lisp
|
||
|
(defun base64 ()
|
||
|
(let ((email *email*))
|
||
|
(loop repeat 100 do
|
||
|
(if (ppcre:scan "@" email)
|
||
|
(print email)
|
||
|
(setf email (cl-base64:base64-string-to-string email))))))
|
||
|
#+end_src
|