Question

3.13 LAB: Extracting Passwords (files and lists)

The Linux operating system is a very popular server OS. A network administrator has to protect the login/password files stored on the servers. In Linux there are two important files:

/etc/passwd

And it contains rows that look like this:

root:x:0:0:root:/root:/bin/bash
bin:x:1:1:bin:/bin:/sbin/nologin
daemon:x:2:2:daemon:/sbin:/sbin/nologin
adm:x:3:4:adm:/var/adm:/sbin/nologin
ftp:x:14:50:FTP User:/var/ftp:/sbin/nologin
user1:x:15:51:User One:/home/user1:nologin
user2:x:15:51:User One:/home/user1:nologin
user3:x:15:51:User One:/home/user1:nologin

This file contains login information. It's a list of the server's accounts that has userID, groupID, home directory, shell and more info.

And the second file /etc/shadow, contains rows that look like this:

root:$1$TDQFedzX$.kv51AjM.FInu0lrH1dY30:15045:0:99999:7:::
bin:*:14195:0:99999:7:::
daemon:*:14195:0:99999:7:::
adm:*:14195:0:99999:7:::
ftp:*:14195:0:99999:7:::
user1:$1$ssTPXdzX$.kv51AjM.FInu0lrH1dY30:15045:0:99999:7:::
user1:44##$TDQFedzX$.Pxp39484.FInu0lrH1dY30:15045:0:99999:7:::
user1:%[email protected]:15045:0:99999:7:::

This file contains the actual password in encrypted format for each of the user's accounts stored in /etc/passwd. Notice the encrypted text after the login and : colon. That is the encrypted password.

Typically, if a hacker obtains access to these files, they could use some sort of cracking software to decrypt the passwords. Basically, they take a Brute Force approach and use common passwords to find a match.

Write a program that first reads in the name of two input files; input1pass.txt and input1shadow.txt. These files will contain encrypted and non-encrypted passwords to simulate a Brute Force approach. Next the program will accept input of two strings representing a potential user name, and password. The files should be read using the file.readlines( ) method.

Your program should output the attempted login and password with a message that it was a successful or unsuccessful brute force attempt.

Ex: If the input is:

input1pass.txt
input1shadow.txt
bobpickle
pa$$w0rd

and the contents of input1pass.txt are:

user1:x:15:51:User One:/home/user1:nologin
user2:x:16:52:User One:/home/user1:nologin
user3:x:17:53:User One:/home/user1:nologin

and the contents of the input1shadow.txt are:

user1:XXPP192920r:15045:0:99999:7:::
user1:LLmm928393x:15046:0:99999:7:::
user1:&^334294kksri.:15047:0:99999:7:::

the output is:

Brute Force Attempt:
Login:  user1
Password:  XXPP192920r
Unsuccessful brute force attempt

Brute Force Attempt:
Login:  user2
Password:  LLmm928393x
Unsuccessful brute force attempt

Brute Force Attempt:
Login:  user3
Password:  &^334294kksri.
Unsuccessful brute force attempt

Ex: If the input is:

input2pass.txt
input2shadow.txt
demo123
password

and the contents of input1pass.txt are:

user1:x:15:51:User One:/home/user1:nologin
user2:x:16:52:User One:/home/user1:nologin
user3:x:17:53:User One:/home/user1:nologin
demo123:x:18:54:Demo User:/home/demo123:nologin

and the contents of the input1shadow.txt are:

user1:XXPP192920r:15045:0:99999:7:::
user1:LLmm928393x:15046:0:99999:7:::
user1:&^334294kksri.:15047:0:99999:7:::
demo123:password:15048:0:99999:7:::

the output is:

Brute Force Attempt:
Login:  user1
Password:  XXPP192920r
Unsuccessful brute force attempt

Brute Force Attempt:
Login:  user2
Password:  LLmm928393x
Unsuccessful brute force attempt

Brute Force Attempt:
Login:  user3
Password:  &^334294kksri.
Unsuccessful brute force attempt

Brute Force Attempt:
Login: demo123
Password: password
Successful brute force attempt

Notes:

• There is a newline at the end of the output.
• input1pass.txt is available to download.
• input1shadow.txt is available to download
• 'Hint' - check out the Python zip ( ) for mapping the login in one file to the other.

279088.991434

LAB ACTIVITY

3.13.1: LAB: Extracting Passwords (files and lists)

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Downloadable files

input1pass.txt

input1shadow.txt

Download

Answer 1

Solution:

In question they asked to use the zip() this method is use to compare the list and group based on the matching word

//import re package to do comapre the password complexity

import re

//Method toread the password file and store each line using while loop its as array
def Read_PasswordFile(filename):
password_array = []
with open(filename) as f:
for line in f:

//fetch only the username from the file using split function
password_array.append(line.split(":")[0])

//return usernamelist
return password_array

//Method toread the shadow file and store each line using while loop its as array
def Read_ShadowFile(filename):
shadow_array = []
with open(filename) as f:
#shadow_array is the list that contains the read lines.   
for line in f:
shadow_array.append(line)

//return array
return shadow_array

//call the respective method by passing the file name

userLogin=Read_PasswordFile('input1pass.txt')
Password=Read_ShadowFile('input1Shadow.txt')

//Using inbuild python zip method map the user and password files array,it will return the tuples

//like this(user1,user1:XXPP192920r:15045:0:99999:7:::)

x = zip(userLogin, Password)

//convert tuples to list for manupulation
mappedLoginList=list(x)

//using lambda separate the user and password details index 0-->holds userb=name,index1 holds password details
users=map(lambda x: x[0], mappedLoginList)
login=map(lambda x: x[1], mappedLoginList)

//Convert maps to list
usersList=list(users)
loginList=list(login)
//regex pattern to check password conatin lower,upper,number and special character
pattern ="^[a-zA-Z0-9@#$%^&+=.]+$"
//this pattern is used o check if password conatin only string
pattern2="^[a-zA-Z]*$"
//this pattern to check if the string conatin only number
pattern3="^[0-9]*$"

//Iterate the list using for loop to check the bruteforce attack

for i in range(0,len(usersList)):

//simple print statement to display output
print("Brute Force Attempt:")
print("Login:",usersList[i])
loginPassword=loginList[i].split(":")[1]
print("Password:",loginPassword)

//if statement to check the passwordcomplexity
  
if(not(re.match(pattern2, loginPassword))and not(re.match(pattern3, loginPassword)) and (re.match(pattern, loginPassword))):
print("Unsuccessful brute force attempt")
else:
print("Successful brute force attempt")
print("\n")