LM Authentication In Windows NT

While backward compatibility is one of the main reasons personal computers are so popular, it can pose a serious potential threat in the area of network security.

Many current operating systems use security protocols that were developed in the 1980's. Since networks were not as widely used in the past, network security wasn't a big issue; thus, network protocols weren't as safe.

For today's systems to work with older systems, they must use the old unsafe network protocols that can be easily cracked. One such protocol is LM authentication, which is an authentication protocol used in Windows 95/98. Many programs have demonstrated how easily LM can be cracked. LM allows passwords longer than seven characters to be attacked in seven-character pieces. In addition, LM supports only uppercase letters, numerals, punctuation characters, and several ALT characters.

One of Windows NT's primary goals is to be compatible with other systems, so Microsoft included support for LM and enabled it by default in Windows NT. Although Windows NT supports NTLM and NTLMv2, the OS still actively uses LM-- because of Windows 95/98 clients that require this authentication protocol.

If you're concerned about network security, you should disable LM. This will tighten security and prevent NT systems from communicating with computers running Windows 95/98.

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