Password cracking is the process of recovering secret passwords from data that has
been stored in or transmitted by a computer system. A common approach is to
repeatedly try guesses for the password.
Most passwords can be cracked by using following techniques :
Here we will refer to the one way function (which may be either an
encryption function or cryptographic hash) employed as a hash and its output as a
If a system uses a reversible function to obscure stored passwords, exploiting that
weakness can recover even ‘well-chosen’ passwords.
One example is the LM hash that Microsoft Windows uses by default to store user
passwords that are less than 15 characters in length.
LM hash breaks the password into two 7-character fields which are then hashed
separately, allowing each half to be attacked separately.
Hash functions like SHA-512, SHA-1, and MD5 are considered impossible to
invert when used correctly.
Many passwords can be guessed either by humans or by sophisticated
cracking programs armed with dictionaries (dictionary based) and the user’s personal
Not surprisingly, many users choose weak passwords, usually one related to
themselves in some way. Repeated research over some 40 years has demonstrated
that around 40% of user-chosen passwords are readily guessable by programs.
Examples of insecure choices include:
* blank (none)
* the word “password”, “passcode”, “admin” and their derivatives
* the user’s name or login name
* the name of their significant other or another person (loved one)
* their birthplace or date of birth
* a pet’s name
* a dictionary word in any language
* automobile licence plate number
* a row of letters from a standard keyboard layout (eg, the qwerty keyboard — qwerty
itself, asdf, or qwertyuiop)
* a simple modification of one of the preceding, such as suffixing a digit or reversing
the order of the letters.
and so on….
In one survery of MySpace passwords which had been phished, 3.8 percent of
passwords were a single word found in a dictionary, and another 12 percent were a
word plus a final digit; two-thirds of the time that digit was.
A password containing both uppercase & lowercase characters, numbers
and special characters too; is a strong password and can never be guessed.
Check Your Password Strength
#Default Passwords :-
A moderately high number of local and online applications
have inbuilt default passwords that have been configured by programmers during
development stages of software. There are lots of applications running on the internet
on which default passwords are enabled. So, it is quite easy for an attacker to enter
default password and gain access to sensitive information. A list containing default
passwords of some of the most popular applications is available on the internet.
Always disable or change the applications’ (both online and offline) default
#Brute Force :-
If all other techniques failed, then attackers uses brute force password cracking technique. Here an automatic tool is used which tries all possible
combinations of available keys on the keyboard. As soon as correct password is
reached it displays on the screen.This techniques takes extremely long time to
complete, but password will surely cracked.
Long is the password, large is the time taken to brute force it.
This is the most effective and easily executable password cracking
technique which is generally used to crack the passwords of e-mail accounts, and all
those accounts where secret information or sensitive personal information is stored by
user such as social networking websites, matrimonial websites, etc.
Phishing is a technique in which the attacker creates the fake login screen and send it
to the victim, hoping that the victim gets fooled into entering the account username and
password. As soon as victim click on “enter” or “login” login button this information
reaches to the attacker using scripts or online form processors while the user(victim) is
redirected to home page of e-mail service provider.
Never give reply to the messages which are demanding for your username-
password, urging to be e-mail service provider.
It is possible to try to obtain the passwords through other different methods, such as
social engineering, wiretapping, keystroke logging, login spoofing, dumpster diving,
phishing, shoulder surfing, timing attack, acoustic cryptanalysis, using a Trojan Horse
or virus, identity management system attacks (such as abuse of Self-service password
reset) and compromising host security.
However, cracking usually designates a guessing attack.
#ADMIN Ahmed Zaid