Several hacker tool's use method _ Security correlation

In this article, the author mainly introduces some tools that hackers use to attack the network. By understanding how these hacking tools are used, readers can better protect their own network security.
Of the ..., 3:45 A.M., the annoying bell will wake you up. " So, you go online to respond to the call, but found that the network has been broken, you have been hacked "black". Moreover, the hacker must be a master, because several servers have stopped working, and there are all the Trojan backdoor programs left behind. God knows what else he's done! What's more, when you check your e-mail, many companies are asking why you are attacking their network. Obviously, hackers have used your mainframe to attack other systems.

To help you better protect against the attacks of the moment, this article describes the popular hacking tools and effective prevention techniques that you can use to secure your network.

Special Notes

This is not a system that teaches you how to attack others, but rather an objective description of what is happening in the real world and provides you with a way to defend against these attacks.

Since these tools can be downloaded for free on the internet, and it can damage your system, the author does not imply that he acquiesced or recommended your use when discussing a tool in the article. The authors caution: When using these tools, you must be cautious and careful, and you have to figure out what the source code means.

Tool One: Password crackers

Password Crackers has become a mainstream tool for hackers because of its wide use. The implementation of password deciphering attacks is divided into two steps, the first step: the attacker first reads an encrypted password file from the victim's computer (most systems, including Windows NT and UNIX, encrypt the password and store it in the file system for authentication when the user logs in); Step two: The attacker uses a dictionary as an aid and begins to attempt to decipher the password with password crackers. The idea is to encrypt each item in the dictionary and then compare the two. If two encrypted passwords match, the hacker will know the password, and if they do not, the tool continues to work until the last entry in the dictionary. Sometimes hackers even try to combine each letter. Using this method, the speed of password decoding is related to the speed of encryption and comparison.

Tool Two: L0phtCrack

L0phtCrack was written by hacker group L0pht Heavy Industries and launched in 1997. It spreads in the form of shareware (shareware). It is specifically used to decipher Windows NT passwords. This tool is powerful and easy to use, and beginners can decipher the password with little pointing. The L0phtCrack version 2.5, launched in January 1999, optimizes the DES cipher program and improves software performance (450% faster than the older version). It is alleged that a single 450 MHz Pentium II
The computer can decipher all alphanumeric passwords in one day.

L0phtCrack can obtain encrypted password files through a variety of channels. The SAM database in the Windows NT system can be obtained as long as the hacker runs a program containing l0phtcrack or copies a program from the backup floppy of the Window NT system administrator. L0phtCrack the latest version of the GUI can get encrypted windows passwords from the network. When you log in to NT domain, your password is sent to the network using a hashing algorithm. L0phtCrack's built-in sniffer can easily find this encrypted value and decipher it.

Since this tool is also of great use to it practitioners, a registration fee is collected from the L0phtCrack 2.0 edition. The latest version can have a 15-day free trial period, more than 15th to charge 100 U.S. dollars, and a number of deciphering procedures to choose from, some charge fees, some can be obtained from the Free Software Library.

Prevention of L0phtCrack

The best way to defend against password-deciphering attacks is to enforce password-guarding policies. For example, requiring a user to assume a password is difficult to guess. If the password should have at least 8 digits, including numbers, letters and special characters (such as!) @#$%); Passwords should not include dictionary words. For further security, some password provisioning tools can help users design complex passwords.

In addition, you should often use password deciphering tools to check whether the company's password is safe. Of course, only security managers or persons authorized by them will be allowed to use the tool and must be approved in writing. At the same time, you should be in advance to the password is unfortunately cracked users to make a solution, choose to send him an email, or visit the user personally, explain your password policy. These issues should be considered completely before the password evaluation.

Tool Three: War dialers

Many companies attach great importance to the security of firewalls. However, this sturdy line of defense only seals the front door of the network, but the unregistered modems in the intranet open the "back door" to intruders. The War dialers can quickly find these modems and then hack into the network.　Therefore, it becomes a very popular tool for intruders. War dialer for the movie "War Games" and fame. Its attack principle is very simple: constantly dialing phone numbers in order or in a disorderly order, looking for familiar response tones after the modem is connected. Once the war dialers has found a whole host of modems, hackers have been dialing into the network to continue to look for unprotected or easily guessed passwords on the system. The War dialers preferred Attack object is the "No password" PC remote management software. These software are typically installed by end users to remotely access the company's internal systems. These PC remote control programs are extremely vulnerable when using an insecure modem.
Thc-scan is the abbreviation for the Hacker ' Choice (THC) scanner. This War dialers tool was written by "Van Hauser". Its function is very complete. The Thc-scan 2.0 edition was launched in 1998 on Christmas Day, Thc-scan and Toneloc (written by "Minor Threat" and "Mucho Maas"). Unlike other common war dialers tools, Thc-scan automatically detects modem speed, data bits, check bits, and stop bits. This tool also attempts to determine the operating system used by the discovered computer. Also, Thc-scan has the ability to confirm when a dial tone is available, so hackers can make toll-free calls without passing through your PBX.

The prevention of War dialers

Of course, the most effective precaution is to use a secure modem. Cancel those modems that do not use. and users must register with the IT department before they can use the modem. For modems that are registered and used only as outgoing, the permissions of the company's PBX are transferred to only external dialing. Each company should have a strict policy to describe the registered modem and control the PBX. Because there is a convenient and inexpensive digital modem for sale in the market store,
Users can also install modems on a PBX with only a digital line.
In addition, you have to conduct regular penetration tests to find out the illegal modems in the telephone exchanger. Use a good tool to find a modem that is connected to your network. For the discovered, but unregistered modems, either remove them or register them again.