Password Cracking Techniques and Countermeasures

Password Cracking Techniques and Countermeasures

1. Dictionary, Brute-Force, and Rule-Based Attack

   • Dictionary Attack: A dictionary file is loaded into the cracking application that runs against user accounts.
   • Brute-Force Attack: The program tries every combination of characters until the password is broken.
   • Rule-based Attack: This attack is used when the attacker gets some information about the password.

2. Types of Password Attacks

   • Non-Electronic Attacks: The attacker does not need technical knowledge to crack the password. (Shoulder surfing, Social Engineering, Dumpster Diving)
   • Active Online Attacks: The attacker performs password cracking by directly communicating with the victim's machine. (Trojan, Spyware, Keyloggers, Hash Injection, NBT-NS Poisoning Etc.)
   • Passive Online Attacks: The attacker performs password cracking without communicating with the authorizing party. (Wire Sniffing, Man-in-the-Middle Attack, Replay Attack)
   • Offline Attacks: The attacker copies the target's password file and then tries to crack passwords on his own system at a different location (Rainbow Table Attack, Distributed Network Attack)

3. Microsoft Authentication

   • Security Accounts Manager (SAM): Mamages user accounts and apsswords in hashed format.
   • NTLM Authentication: A default authentication scheme that performs authentication using a challenge.response strategy. Because it does not rely on any official protocol specification, there is no guarantee that it works effectively in every situation.
   • Kerberos Authentication: A network authentication protocol that provides strong authentication for client/server application through secret-key cryptography. This protocol provides mutual authentication, in that both the server and the user verify each other's identity.

4. Trojans/Spyware/Keyloggers

   • Trojan: A program that asks itself as a benign application. The software initially appears to perform a desirable or benign function, but instead steals information or harms the system.
   • Spyware: A type of malware that attackers install on a computer to secretly gather information about its users without their knowledge.
   • Keylogger: A program that records all user keystrokes without the user's knowledge. Keyloggers ship the log of user keystrokes to an attacker's machine or hide it in the victim's machine for later retrieval.

5. Techniques

   • Hash Injection: Uses a hash function as part of the authentication process to authenticate users.
   • LLMNR/NBT-NS: Main elements of Windows operating systems that are used to perform name resolution of hosts present on the same link.
   • Wire Sniffing: A form of wire sniffing or wiretapping in which hackers sniff credentials during transit by capturing Internet packets.

6. Counter measures

   • 2) Disallow password sharing.
   • 3) Disallow the use of passwords that can be founded in a dictionary.
   • 4) Do not use cleartext protocols and protocols with weak encryption.
   • 5) Set the password change policy to 30 days.
   • 6) Do not use any system default passwords.
   • 7) Make passwords hard to guess by requiring 8-12 alphanumeric characters.
   • 8) Ensure that applications neither store passwords in memory nor write them to disks in clear text.
   • 9) Use a random string(salt) as a prefix
   • 10) Disallow the use of passwords such as date of birth, spouse, child's, or pet's name.
   • 1) Disallow use of the same password during a password change.
   • 11) Lockout an account subjected to too many incorrect password guesses.
   • 12) Use two-factor or multifactor authentication.