How Hackers Crack Passwords

Password cracking is one of the most enjoyable hacks for the bad guys. It fuels their sense of exploration and desire to figure out a problem. A hacker can use low-tech methods to crack passwords. These methods include using social engineering techniques, shoulder surfing, and simply guessing passwords from information that he knows about the user.

Social engineering

The most popular low-tech method for gathering passwords is social engineering. Social engineering takes advantage of the trusting nature of human beings to gain information that later can be used maliciously. A common social engineering technique is simply to con people into divulging their passwords. It sounds ridiculous, but it happens all the time.


To obtain a password through social engineering, you just ask for it. For example, you can simply call a user and tell him that he has some important-looking e-mails stuck in the mail queue, and you need his password to log in and free them up. This is often how hackers and rogue insiders try to get the information!

A common weakness that can facilitate such social engineering is when staff members' names, phone numbers, and e-mail addresses are posted on your company websites. Social media sites such as LinkedIn, Facebook, and Twitter can also be used against a company because these sites can reveal employees' names and contact information.


User awareness and consistent security training are great defenses against social engineering. Security tools are a good fail-safe if they monitor for such e-mails and web browsing at the host-level, network perimeter, or in the cloud.

Train users to spot attacks and respond effectively. Their best response is not to give out any information and to alert the appropriate information security manager in the organization to see whether the inquiry is legitimate and whether a response is necessary. Oh, and take that staff directory off your website or at least remove IT staff members' information.

Shoulder surfing

Shoulder surfing (the act of looking over someone's shoulder to see what the person is typing) is an effective, low-tech password hack.


To mount this attack, the bad guys must be near their victims and not look obvious. They simply collect the password by watching either the user's keyboard or screen when the person logs in.

An attacker with a good eye might even watch whether the user is glancing around his desk for either a reminder of the password or the password itself. Security cameras or a webcam can even be used for such attacks. Coffee shops and airplanes provide the ideal scenarios for shoulder surfing.

You can try shoulder surfing yourself. Simply walk around the office and perform random spot checks. Go to users' desks and ask them to log in to their computers, the network, or even their e-mail applications. Just don't tell them what you're doing beforehand, or they might attempt to hide what they're typing or where they're looking for their password. Just be careful doing this and respect other people's privacy.


Encourage users to be aware of their surroundings and not to enter their passwords when they suspect that someone is looking over their shoulders. Instruct users that if they suspect someone is looking over their shoulders while they're logging in, they should politely ask the person to look away or, when necessary, hurl an appropriate epithet to show the offender that the user is serious.


Inference is simply guessing passwords from information you know about users - such as their date of birth, favorite television show, or phone numbers. It sounds silly, but criminals often determine their victims' passwords simply by guessing them!

The best defense against an inference attack is to educate users about creating secure passwords that don't include information that can be associated with them. Outside of certain password complexity filters, it's often not easy to enforce this practice with technical controls. So, you need a sound security policy and ongoing security awareness and training to remind users of the importance of secure password creation.

Weak authentication

External attackers and malicious insiders can obtain - or simply avoid having to use - passwords by taking advantage of older or unsecured operating systems that don't require passwords to log in. The same goes for a phone or tablet that isn't configured to use passwords.

Bypassing authentication

On older operating systems that prompt for a password, you can press Esc on the keyboard to get right in. Okay, it's hard to find any Windows 9x systems these days, but the same goes for any operating system - old or new - that's configured to bypass the login screen.

After you're in, you can find other passwords stored in such places as dialup and VPN connections and screen savers. Such passwords can be cracked very easily using Elcomsoft's Proactive System Password Recovery tool and Cain & Abel. These weak systems can serve as trusted machines - meaning that people assume they're secure - and provide good launching pads for network-based password attacks as well.


The only true defense against weak authentication is to ensure your operating systems require a password upon boot. To eliminate this vulnerability, at least upgrade to Windows 7 or 8 or use the most recent versions of Linux or one of the various flavors of UNIX, including Mac OS X.

This is a excerpt from Hacking For Dummies

The best way to stay safe online is to stop hackers before they attack - first, by understanding their thinking and second, by ethically hacking your own site to measure the effectiveness of your security. This practical, top-selling guide will help you do both. Fully updated for Windows 8 and the latest version of Linux, Hacking For Dummies, 4th Edition explores the malicious hacker's mindset and helps you develop an ethical hacking plan (also known as penetration testing) using the newest tools and techniques.

More timely than ever, this must-have book covers the very latest threats, including web app hacks, database hacks, VoIP hacks, and hacking of mobile devices.

Guides you through the techniques and tools you need to stop hackers before they hack you
Completely updated to examine the latest hacks to Windows 8 and the newest version of Linux
Explores the malicious hackers's mindset so that you can counteract or avoid attacks completely
Suggests ways to report vulnerabilities to upper management, manage security changes, and put anti-hacking policies and procedures in place

If you're responsible for security or penetration testing in your organization, or want to beef up your current system through ethical hacking, make sure you get Hacking For Dummies

More Windows Administration Information:
• Computer Architecture, Operation of Microprocessor, and the CISSP Exam
• Top Tips To Secure Your Online PC
• How to Protect Yourself Against Keyloggers
• Six Steps to Get and Keep Your Computer Running at Full Speed
• Fundamentals of Windows Security
• Tips to Protect Windows Vista Operating System
• DriveLock Hard Drive Protection
• Keep Your Firefox Browsing Private
• FREE Antivirus Software AVG
• How Many Spyware Items Are Slowing Down Your Computer?