![]() Once extracted, you can use a tool called Mimikatz to extract user names and password hashes from the registry file. It is possible to extract SAM data from the Windows registry. However, there is another, more practical, way to extract a machine’s password hashes, and it does not require physical access to the machine. That means that if you want to make a copy of the SAM, you will need physical access to the machine and the ability to boot to a secondary operating system. Downloading a copy of a machine’s SAM generally requires Windows to be offline. ![]() Some people dismiss the threat of rainbow tables because they require access to a system’s password database (the Security Accounts Manager, or SAM). This system was initially immune to rainbow table cracking, but rainbow tables now exist for both LM and NTLM hashes. Microsoft eventually adopted a new password mechanism, NTLMv2, that was far more secure than LanMan. These passwords were notoriously easy to crack, with a 14-character limit. These were the passwords used in Windows XP and earlier operating systems. Īttackers used rainbow tables early on to crack LAN Manager (LanMan or LM) passwords. However, rainbow tables are available for download from sources such as Ophcrack. Needless to say, building a rainbow table from scratch would be a big undertaking. Using this method can reduce the amount of time required to crack a password from weeks to minutes or hours. If a matching hash is found, the password will be revealed. The next time the attacker needs to crack a password, he or she can compare the password hash against the values stored in the table. With rainbow tables, an attacker calculates hashes once and saves them to a lookup table (which has come to be known as a rainbow table). This is an extremely time-consuming process. ![]() Therefore, when an attacker performs a brute force crack, they will typically use a program to calculate a hash for every possible password and then compare that hash against the hash that is stored in the password database. The hashing process cannot be reversed to reveal the password. Instead, the operating system uses an algorithm to create mathematical hashes of passwords, and those hashes are what is actually stored. ![]() Operating systems such as Windows do not store passwords in clear text. Rainbow tables are a password cracking tool that greatly expedites the cracking process. Even so, rainbow tables have evolved over time and remain a threat to password security. Some people have dismissed rainbow tables as being a legacy tool that is ineffective in today’s world. Rainbow tables allow an attacker to crack passwords far more quickly than is possible using other methods, such as brute force attacks. ![]()
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