Chapter 8
In This Chapter
Identifying password vulnerabilities
Examining password-hacking tools and techniques
Hacking operating system passwords
Hacking password-protected files
Protecting your systems from password hacking
Password hacking is one of the easiest and most common ways attackers obtain unauthorized network, computer, or application access. You often hear about it in the headlines, and study after study such as the Verizon Data Breach Investigations Report reaffirms that weak passwords are at the root of many security problems. I have trouble wrapping my head around the fact that I’m still talking about (and businesses are suffering from) weak passwords, but it’s a reality — and, as an information security testing professional, you can certainly do your part to minimize the risks.
Although strong passwords — ideally, longer and stronger passphrases that are difficult to crack (or guess) — are easy to create and maintain, network administrators and users often neglect this. Therefore, passwords are one of the weakest links in the information security chain. Passwords rely on secrecy. After a password is compromised, its original owner isn’t the only person who can access the system with it. That’s when accountability goes out the window and bad things start happening.
External attackers and malicious insiders have many ways to obtain passwords. They can glean passwords simply by asking for them or by looking over the shoulders of users (shoulder surfing) while they type their passwords. Hackers can also obtain passwords from local computers by using password-cracking software. To obtain passwords from across a network, attackers can use remote cracking utilities, keyloggers, or network analyzers.
This chapter demonstrates how easily the bad guys can gather password information from your network and computer systems. I outline common password vulnerabilities and describe countermeasures to help prevent these vulnerabilities from being exploited on your systems. If you perform the tests and implement the countermeasures outlined in this chapter, you’ll be well on your way to securing your systems’ passwords.
When you balance the cost of security and the value of the protected information, the combination of a user ID and a secret password is usually adequate. However, passwords give a false sense of security. The bad guys know this and attempt to crack passwords as a step toward breaking into computer systems.
One big problem with relying solely on passwords for security is that more than one person can know them. Sometimes, this is intentional; often, it’s not. The tough part is that there’s no way of knowing who, besides the password’s owner, knows a password.
Here are the two general types of password vulnerabilities:
I explore each of these classifications in more detail in the following sections.
Before computer networks and the Internet, the user’s physical environment was an additional layer of password security that actually worked pretty well. Now that most computers have network connectivity, that protection is gone. Refer to Chapter 7 for details on managing physical security in this age of networked computers and mobile devices.
It’s human nature to want convenience, especially when it comes to remembering five, ten, and often dozens of passwords for work and daily life. This desire for convenience makes passwords one of the easiest barriers for an attacker to overcome. Almost 3 trillion (yes, trillion with a t and 12 zeros) eight-character password combinations are possible by using the 26 letters of the alphabet and the numerals 0 through 9. The keys to strong passwords are: 1) easy to remember and 2) difficult to crack. However, most people just focus on the easy-to-remember part. Users like to use such passwords as password, their login name, abc123, or no password at all! Don’t laugh; I’ve seen these blatant weaknesses and guarantee they’re on any given network this very moment.
Unless users are educated and reminded about using strong passwords, their passwords usually are
Reused for many security points. When bad guys crack one password, they can often access other systems with that same password and username.
Using the same password across multiple systems and websites is nothing but a breach waiting to happen. Everyone is guilty of it, but that doesn’t make it right. Do what you can to protect your own credentials and spread the word to your users about how this practice can get you into a real bind.
You can often find these serious technical vulnerabilities after exploiting organizational password vulnerabilities:
Weak password encryption schemes. Hackers can break weak password storage mechanisms by using cracking methods that I outline in this chapter. Many vendors and developers believe that passwords are safe as long as they don’t publish the source code for their encryption algorithms. Wrong! A persistent, patient attacker can usually crack this security by obscurity (a security measure that’s hidden from plain view but can be easily overcome) fairly quickly. After the code is cracked, it is distributed across the Internet and becomes public knowledge.
Password cracking utilities take advantage of weak password encryption. These utilities do the grunt work and can crack any password, given enough time and computing power.
The National Vulnerability Database (an index of computer vulnerabilities managed by the National Institute of Standards and Technology) currently identifies over 2,300 password-related vulnerabilities! You can search for these issues at http://nvd.nist.gov
to find out how vulnerable some of your systems are from a technical perspective.
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. You might not have a burning desire to explore everyone’s passwords, but it helps to approach password cracking with this mindset. So where should you start testing the passwords on your systems? Generally, any user’s password works. After you obtain one password, you can often obtain others — including administrator or root passwords.
Administrator passwords are the pot of gold. With unauthorized administrative access, you (or a criminal hacker) can do virtually anything on the system. When looking for your organization’s password vulnerabilities, I recommend first trying to obtain the highest level of access possible (such as administrator) through the most discreet method possible. That’s often what the criminals do.
You can use low-tech ways and high-tech ways to exploit vulnerabilities to obtain passwords. For example, you can deceive users into divulging passwords over the telephone or simply observe what a user has written down on a piece of paper. Or you can capture passwords directly from a computer, over a network, and via the Internet with the tools covered in the following sections.
A hacker can use low-tech methods to crack passwords. These methods include using social engineering techniques such as phishing, shoulder surfing, and simply guessing passwords from information that he knows about the user.
The most popular low-tech method for gathering passwords is social engineering, which I cover in detail in Chapter 6. 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!
Another way to get users to divulge their passwords is to send a phishing e-mail simply requesting that information. I have found that asking users to confirm their understanding and compliance with internal security policies by submitting their login credentials to a phishing website is all it takes. I cover e-mail phishing in greater detail in Chapter 6.
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 website. 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 (such as suspicious phone calls or deceitful phishing e-mails) 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 (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 — two things that they should’ve been doing all along! 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. It’s often easiest to just lean into the shoulder surfer’s line of sight to keep them from seeing any typing and/or the computer screen. 3M Privacy Filters (www.shop3m.com/3m-privacy-filters.html
) work great as well yet, surprisingly, I rarely see them being used.
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.
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.
On older operating systems (such as Windows 9x) 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 (www.elcomsoft.com/pspr.html
) and Cain & Abel (www.oxid.it/cain.html
). 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, if not Windows 10, or use the most recent versions of Linux or one of the various flavors of UNIX, including Mac OS X and Chrome OS.
High-tech password cracking involves using a program that tries to guess a password by determining all possible password combinations. These high-tech methods are mostly automated after you access the computer and password database files.
The main password-cracking methods are dictionary attacks, brute-force attacks, and rainbow attacks. You find out how each of these work in the following sections.
You can try to crack your organization’s operating system and application passwords with various password-cracking tools:
www.hoobie.net/brutus
) cracks logons for HTTP, FTP, telnet, and more.www.oxid.it/cain.html
) cracks LM and NT LanManager (NTLM) hashes, Windows RDP passwords, Cisco IOS and PIX hashes, VNC passwords, RADIUS hashes, and lots more. (Hashes are cryptographic representations of passwords.)www.elcomsoft.com/edpr.html
) cracks Windows, Microsoft Office, PGP, Adobe, iTunes, and numerous other passwords in a distributed fashion using up to 10,000 networked computers at one time. Plus, this tool uses the same graphics processing unit (GPU) video acceleration as the ElcomSoft Wireless Auditor tool, which allows for cracking speeds up to 50 times faster. (I talk about the ElcomSoft Wireless Auditor tool in Chapter 10.)www.elcomsoft.com/esr.html
) cracks or resets Windows user passwords, sets administrative rights, and resets password expirations all from a bootable CD. This is a great tool for demonstrating what can happen when laptop computers do not have full disk encryption.www.openwall.com/john
) cracks hashed Linux/UNIX and Windows passwords.http://ophcrack.sourceforge.net
) cracks Windows user passwords using rainbow tables from a bootable CD. Rainbow tables are pre-calculated password hashes that can help speed up the cracking process by comparing these hashes with the hashes obtained from the specific passwords being tested.www.elcomsoft.com/ppa.html
) runs brute-force, dictionary, and rainbow cracks against extracted LM and NTLM password hashes.www.elcomsoft.com/pspr.html
) recovers practically any locally stored Windows password, such as logon passwords, WEP/WPA passphrases, SYSKEY passwords, and RAS/dialup/VPN passwords.www.openwall.com/passwords/microsoft-windows-nt-2000-xp-2003-vista-7
) extracts Windows password hashes from the SAM (Security Accounts Manager) database.http://project-rainbowcrack.com
) cracks LanManager (LM) and MD5 hashes very quickly by using rainbow tables.www.thc.org/thc-hydra
) cracks logons for HTTP, FTP, IMAP, SMTP, VNC and many more.To understand how the preceding password-cracking programs generally work, you first need to understand how passwords are encrypted. Passwords are typically encrypted when they’re stored on a computer, using an encryption or one-way hash algorithm, such as SHA2 or MD5. Hashed passwords are then represented as fixed-length encrypted strings that always represent the same passwords with exactly the same strings. These hashes are irreversible for all practical purposes, so, in theory, passwords can never be decrypted. Furthermore, certain passwords, such as those in Linux, have a random value called a salt added to them to create a degree of randomness. This prevents the same password used by two people from having the same hash value.
Password-cracking utilities take a set of known passwords and run them through a password-hashing algorithm. The resulting encrypted hashes are then compared at lightning speed to the password hashes extracted from the original password database. When a match is found between the newly generated hash and the hash in the original database, the password has been cracked. It’s that simple.
Other password-cracking programs simply attempt to log on using a predefined set of user IDs and passwords. This is how many dictionary-based cracking tools work, such as Brutus (www.hoobie.net/brutus
) and SQLPing3 (www.sqlsecurity.com/downloads
). I cover cracking web application and database passwords in Chapters 15 and 16.
Passwords that are subjected to cracking tools eventually lose. You have access to the same tools as the bad guys. These tools can be used for both legitimate security assessments and malicious attacks. You want to find password weaknesses before the bad guys do, and in this section, I show you some of my favorite methods for assessing Windows and Linux/UNIX passwords.
Windows usually stores passwords in these locations:
Windows may also store passwords in a backup of the SAM file in the c:winnt epair or c:windows epair directory.
Some Windows applications store passwords in the Registry or as plain-text files on the hard drive! A simple registry or file-system search for “password” may uncover just what you’re looking for.
Dictionary attacks quickly compare a set of known dictionary-type words — including many common passwords — against a password database. This database is a text file with hundreds if not thousands of dictionary words typically listed in alphabetical order. For instance, suppose that you have a dictionary file that you downloaded from one of the sites in the following list. The English dictionary file at the Purdue site contains one word per line starting with 10th, 1st … all the way to zygote.
Many password-cracking utilities can use a separate dictionary that you create or download from the Internet. Here are some popular sites that house dictionary files and other miscellaneous word lists:
Don’t forget to use other language files as well, such as Spanish and Klingon.
Brute-force attacks can crack practically any password, given sufficient time. Brute-force attacks try every combination of numbers, letters, and special characters until the password is discovered. Many password-cracking utilities let you specify such testing criteria as the character sets, password length to try, and known characters (for a “mask” attack). Sample Proactive Password Auditor brute-force password-cracking options are shown in Figure 8-1.
Can an expiring password deter a hacker’s attack and render password cracking software useless? Yes. After the password is changed, the cracking must start again if the hacker wants to test all the possible combinations. This is one reason why it’s a good idea to change passwords periodically. Still, I’m not a big fan of forcing users to change their passwords often. Shortening the change interval can reduce the risk of passwords being cracked but can also be politically unfavorable in your business and end up creating the opposite effect you’re going for. You have to strike a balance between security and convenience and usability. In many situations, I don’t think it’s unreasonable to require password changes every 6 to 12 months or after a suspected compromise.
A rainbow password attack uses rainbow cracking to crack various password hashes for LM, NTLM, Cisco PIX, and MD5 much more quickly and with extremely high success rates (near 100 percent). Password cracking speed is increased in a rainbow attack because the hashes are precalculated and thus don’t have to be generated individually on the fly as they are with dictionary and brute-force cracking methods.
If you have a good set of rainbow tables, such as those offered via the ophcrack site and Project RainbowCrack (http://project-rainbowcrack.com
), you can crack passwords in seconds, minutes, or hours versus the days, weeks, or even years required by dictionary and brute-force methods.
The following steps use two of my favorite utilities to test the security of current passwords on Windows systems:
The following test requires administrative access to either your Windows standalone workstation or the server:
Download and install a decompression tool if you don’t already have one.
WinZip (www.winzip.com
) is a good commercial tool I use and 7-Zip (www.7-zip.org
) is a free decompression tool. Windows also includes built-in Zip file handling, albeit a bit kludgy.
www.openwall.com/passwords/microsoft-windows-nt-2000-xp-2003-vista-7
.www.openwall.com/john
.c:passwordspwdump3 > cracked.txt
This file captures the Windows SAM password hashes that are cracked with John the Ripper. Figure 8-2 shows the contents of the cracked.txt file that contains the local Windows SAM database password hashes.
c:passwordsjohn cracked.txt
This process — shown in Figure 8-3 — can take seconds or days, depending on the number of users and the complexity of their associated passwords. My Windows example took only five seconds to crack five weak passwords.
John the Ripper can also crack UNIX/Linux passwords. You need root access to your system and to the password (/etc/passwd) and shadow password (/etc/shadow) files. Perform the following steps for cracking UNIX/Linux passwords:
www.openwall.com/john
.[root@localhost kbeaver]#tar -zxf john-1.8.0.tar.xz
or whatever the current filename is.
You can also crack UNIX or Linux passwords on a Windows system by using the Windows/DOS version of John the Ripper.
make generic
./unshadow /etc/passwd /etc/shadow > cracked.txt
The unshadow process won’t work with all UNIX variants.
./john cracked.txt
When John the Ripper is complete (and this could take some time), the output is similar to the results of the preceding Windows process. (Refer to Figure 8-3.)
After completing the preceding Windows or UNIX steps, you can either force users to change passwords that don’t meet specific password policy requirements, you can create a new password policy, or you can use the information to update your security awareness program. Just do something.
Do you wonder how vulnerable password-protected word-processing, spreadsheet, and Zip files are when users send them into the wild blue yonder? Wonder no more. Some great utilities can show how easily passwords are cracked.
Most password-protected files can be cracked in seconds or minutes. You can demonstrate this “wow factor” security vulnerability to users and management. Here’s a hypothetical scenario that could occur in the real world:
The CFO sends the spreadsheet as an e-mail attachment, assuming that the e-mail will reach its destination.
The financial advisor’s network has content filtering, which monitors incoming e-mails for keywords and file attachments. Unfortunately, the financial advisory firm’s network administrator is looking in the content-filtering system to see what’s coming in.
www.elcomsoft.com/archpr.html
) that can help him out so he proceeds to use it to crack the password.Cracking password-protected files is as simple as that! Now all that the rogue network administrator must do is forward the confidential spreadsheet to his buddies or to the company’s competitors.
I recommend performing these file-password-cracking tests on files that you capture with a content filtering or network analysis tool. This is a good way to determine whether your users are adhering to policy and using adequate passwords to protect sensitive information they’re sending.
The best defense against weak file password protection is to require your users to use a stronger form of file protection, such as PGP, or the AES encryption that’s built in to WinZip, when necessary. Ideally, you don’t want to rely on users to make decisions about what they should use to secure sensitive information, but it’s better than nothing. Stress that a file encryption mechanism, such as a password-protected Zip file, is secure only if users keep their passwords confidential and never transmit or store them in unsecure cleartext (such as in a separate e-mail).
If you’re concerned about unsecure transmissions through e-mail, consider using a content-filtering system or a data loss–prevention system to block all outbound e-mail attachments that aren’t protected on your e-mail server.
Over the years, I’ve found other ways to crack (or capture) passwords technically and through social engineering.
One of the best techniques for capturing passwords is remote keystroke logging — the use of software or hardware to record keystrokes as they’re typed into the computer.
With keystroke-logging tools, you can assess the log files of your application to see what passwords people are using:
www.spector360.com
). Dozens of other such tools are available on the Internet.www.keyghost.com
), fit between the keyboard and the computer or replace the keyboard altogether.The best defense against the installation of keystroke-logging software on your systems is to use an anti-malware program or similar endpoint protection software that monitors the local host. It’s not foolproof but can help. As for physical keyloggers, you’ll need to visually inspect each system.
Many legacy and standalone applications, such as e-mail, dial-up network connections, and accounting software, store passwords locally, making them vulnerable to password hacking. By performing a basic text search, I’ve found passwords stored in cleartext on the local hard drives of machines. You can automate the process even further by using a program called FileLocator Pro (www.mythicsoft.com
). I cover these file and related storage vulnerabilities in Chapter 16.
You can try using your favorite text-searching utility — such as the Windows search function, findstr, or grep — to search for password or passwd on your computer’s drives. You might be shocked to find what’s on your systems. Some programs even write passwords to disk or leave them stored in memory.
The only reliable way to eliminate weak password storage is to use only applications that store passwords securely. This might not be practical, but it’s your only guarantee that your passwords are secure. Another option is to instruct users not to store their passwords when prompted.
Before upgrading applications, contact your software vendor to see how they manage passwords, or search for a third-party solution.
A network analyzer sniffs the packets traversing the network. This is what the bad guys do if they can gain control of a computer, tap into your wireless network, or gain physical network access to set up their network analyzer. If they gain physical access, they can look for a network jack on the wall and plug right in!
Figure 8-4 shows how crystal-clear passwords can be through the eyes of a network analyzer. This figure shows how Cain & Abel (www.oxid.it/cain.html
) can glean thousands of passwords going across the network in a matter of a couple of hours. As you can see in the left pane, these cleartext password vulnerabilities can apply to FTP, web, telnet, and more. (The actual usernames and passwords are blurred out to protect them.)
Cain & Abel is a password-cracking tool that also has network analysis capabilities. You can also use a regular network analyzer, such as the commercial products OmniPeek (www.savvius.com/products/overview/omnipeek_family/omnipeek_network_analysis
) and CommView (www.tamos.com/products/commview
) as well as the free open source program, Wireshark (www.wireshark.org
). With a network analyzer, you can search for password traffic in various ways. For example, to capture POP3 password traffic, you can set up a filter and a trigger to search for the PASS command. When the network analyzer sees the PASS command in the packet, it captures that specific data.
Network analyzers require you to capture data on a hub segment of your network or via a monitor/mirror/span port on a switch. Otherwise, you can’t see anyone else’s data traversing the network — just yours. Check your switch’s user guide for whether it has a monitor or mirror port and instructions on how to configure it. You can connect your network analyzer to a hub on the public side of your firewall. You’ll capture only those packets that are entering or leaving your network — not internal traffic. I cover this type of network infrastructure hacking in detail in Chapter 9.
Here are some good defenses against network analyzer attacks:
http://sniffdet.sourceforge.net
) for UNIX-based systems and PromiscDetect (http://ntsecurity.nu/toolbox/promiscdetect
) for Windows can detect network cards in promiscuous mode (accepting all packets, whether destined for the local machine or not). A network card in promiscuous mode signifies that a network analyzer may be running on the network.Most computer BIOS (basic input/output system) settings allow power-on passwords and/or setup passwords to protect the computer’s hardware settings that are stored in the CMOS chip. Here are some ways around these passwords:
There are tons of variables for hacking and hacking countermeasures depending on your hardware setup. If you plan to hack your own BIOS passwords, check for information in your user manual or refer to the BIOS password-hacking guide I wrote at http://searchenterprisedesktop.techtarget.com/tutorial/BIOS-password-hacking
. If protecting the information on your hard drives is your ultimate goal, then full (sometimes referred to as whole) disk is the best way to go. I cover mobile-related password cracking in-depth in Chapter 11. The good news is that newer computers (within the past five years or so) are using a new type of BIOS called unified extensible firmware interface (UEFI), which is much more resilient to boot-level system cracking attempts. Still, a weak password may be all it takes for the system to be exploited.
Bad guys often exploit user accounts that have just been created or reset by a network administrator or help desk. New accounts might need to be created for new employees or even for your own security testing purposes. Accounts might need to be reset if users forget their passwords or if the accounts have been locked out because of failed attempts.
Here are some reasons why user accounts can be vulnerable:
The best defenses against attacks on passwords in limbo are solid help desk policies and procedures that prevent weak passwords from being available at any given time during the new account generation and password reset processes. Perhaps the best ways to overcome this vulnerability are as follows:
I cover mobile-related password cracking in Chapter 11 and website/application password cracking in Chapter 15.
A password for one system usually equals passwords for many other systems because many people use the same (or at least similar) passwords on every system they use. For this reason, you might want to consider instructing users to create different passwords for different systems, especially on the systems that protect information that’s more sensitive. The only downside to this is that users have to keep multiple passwords and, therefore, might be tempted to write them down, which can negate any benefits.
If you have to choose between weak passwords that your users can memorize and strong passwords that your users must write down, I recommend having readers write down passwords and store the information securely. Train users to store their written passwords in a secure place — not on keyboards or in easily cracked password-protected computer files (such as spreadsheets). Users should store a written password in any of these locations:
http://lastpass.com
)http://passwordsafe.sourceforge.net
)Again, as I mentioned earlier, applications such as these are not impervious to attack so be careful.
As an ethical hacker, you should show users the importance of securing their passwords. Here are some tips on how to do that:
Enforce (or at least encourage the use of) a strong password-creation policy that includes the following criteria:
Here are some other password hacking countermeasures that I recommend:
Test your applications to make sure they aren’t storing passwords indefinitely in memory or writing them to disk. A good tool for this is WinHex (www.winhex.com/winhex/index-m.html
). I’ve used this tool to search a computer’s memory for password, pass=, login, and so on and have come up with some passwords that the developers thought were cleared from memory.
Some password-cracking Trojan-horse applications are transmitted through worms or simple e-mail attachments. Such malware can be lethal to your password-protection mechanisms if they’re installed on your systems. The best defense is malware protection or whitelisting software, from Webroot, McAfee, or Bit9.
www.systemtools.com/somarsoft/?somarsoft.com
), a tool that can enumerate the Windows operating system and gather user IDs and other information.As the security manager in your organization, you can enable account lockout to prevent password-cracking attempts. Account lockout is the ability to lock user accounts for a certain time after a certain number of failed login attempts has occurred. Most operating systems (and some applications) have this capability. Don’t set it too low (fewer than five failed logins), and don’t set it too high to give a malicious user a greater chance of breaking in. Somewhere between 5 and 50 might work for you. I usually recommend a setting of around 10 or 15. Consider the following when configuring account lockout on your systems:
A failed login counter can increase password security and minimize the overall effects of account lockout if the account experiences an automated attack. A login counter can force a password change after a number of failed attempts. If the number of failed login attempts is high and occurred over a short period, the account has likely experienced an automated password attack.
Other password-protection countermeasures include
You can implement various operating system security measures to ensure that passwords are protected.
The following countermeasures can help prevent password hacks on Windows systems:
www.sans.org
), NIST (http://csrc.nist.gov
), the Center for Internet Security Benchmarks/Scoring Tools (www.cisecurity.org
), and the ones outlined in Network Security For Dummies by Chey Cobb.Disable the storage of LM hashes in Windows for passwords that are shorter than 15 characters.
For example, you can create and set the NoLMHash registry key to a value of 1 under HKEY_LOCAL_MACHINESYSTEMCurrentControlSetControlLsa.
Chapter 12 covers Windows hacks you need to understand and test in more detail.
The following countermeasures can help prevent password cracks on Linux and UNIX systems:
Chapter 13 explains the Linux hacks and how to test Linux systems for vulnerabilities.
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