myCode

# -*- coding: utf-8 -*-
import requests
import re
import base64
import os

# ENTER LOGIN BELOW
username = "USERNAME"
password = "PASSWORD"

####################

sess=requests.Session()

#setting flag to verify base64 encoding in the last loop
flag=1

login_url='https://ringzer0ctf.com/login'
URL='http://ringzer0ctf.com/challenges/15'

def login(): #logs you in and prints status
    login_data=dict(username=username,password=password)
    r1=sess.post(login_url,data=login_data)
    print r1.status_code

def getMessage():#gets the message in this case the base64 you can just print msg.lstrip() to confirm its correct
    login()
    r2=sess.get(URL)
    msg = r2.text.splitlines()[71].strip('<br />')
    return msg.lstrip()


def submit_answer(ansr): #submits the answer and then finds the flag
    r3=sess.get(URL+"/"+str(ansr))
    flag=re.findall(r'FLAG-\w+',r3.text)
    print flag

def decodedata(dat): #decodes the base64
    return base64.b64decode(dat)

def check(data): #verifies if the first 5 places in the given data is either alphabet or number  if  not then obviously binary data
    if (re.search(r'^[A-Za-z0-9+/]{5}', data)):
        flag=1
    else:
        flag=0
    return flag

#below function takes the binary data writes it in a binary file , makes it executable
#then executes it stores the output in a string called stri and returns it
def makeElf_and_execute(dta):
    f=open("elfFile","wb")
    f.write(dta[::-1])
    f.close()
    os.system('chmod +x elfFile')
    stri=os.popen('./elfFile').read()
    return stri


dat=getMessage() #gets the base64 data

#the 3 line code below just takes the binary data and decodes it if its base64 then flag remains 1 when the check() function
#detects that its not base64 it makes flag=0 and thus looping ends
while(flag==1):
    dat=decodedata(dat)
    flag=check(dat)

#submit the answer
answer=makeElf_and_execute(dat)
print answer