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LAN Manager
Developer	Microsoft, 3Com
OS family	OS/2
Working state	Discontinued
Source model	Closed source
Initial release	1987; 33 years ago
Final release	2.2a / 1994; 26 years ago
Marketing target	Local area networking
Update method	Re-installation
Package manager	None
Platforms	x86
License	Proprietary
Preceded by	MS-Net, Xenix-NET, 3+Share

LAN Manager was a network operating system (NOS) available from multiple vendors and developed by Microsoft in cooperation with 3Com Corporation. It was designed to succeed 3Com's 3+Sharenetwork server software which ran atop a heavily modified version of MS-DOS.

History[edit]

LAN Manager was based on the OS/2 operating system co-developed by IBM and Microsoft. It originally used the Server Message Block (SMB) protocol atop either the NetBIOS Frames (NBF) protocol or a specialized version of the Xerox Network Systems (XNS) protocol. These legacy protocols had been inherited from previous products such as MS-Net for MS-DOS, Xenix-NET for MS-Xenix, and the afore-mentioned 3+Share. A version of LAN Manager for Unix-based systems called LAN Manager/X was also available.

In 1990, Microsoft announced LAN Manager 2.0 with a host of improvements, including support for TCP/IP as a transport protocol. The last version of LAN Manager, 2.2, which included an MS-OS/2 1.31 base operating system, remained Microsoft's strategic server system until the release of Windows NT Advanced Server in 1993.

Versions[edit]

1987 – MS LAN Manager 1.0 (Basic/Enhanced)
1989 – MS LAN Manager 1.1
1991 – MS LAN Manager 2.0
1992 – MS LAN Manager 2.1
1992 – MS LAN Manager 2.1a
1993 – MS LAN Manager 2.2
1994 – MS LAN Manager 2.2a

Many vendors shipped licensed versions, including:

LM hash details[edit]

LM hash (also known as LanMan hash or LAN Manager hash) is a compromised password hashing function that was the primary hash that Microsoft LAN Manager and Microsoft Windows versions prior to Windows NT used to store user passwords. Support for the legacy LAN Manager protocol continued in later versions of Windows for backward compatibility, but was recommended by Microsoft to be turned off by administrators; as of Windows Vista, the protocol is disabled by default, but continues to be used by some non-Microsoft SMB implementations.

Algorithm[edit]

The LM hash is computed as follows:^[1]^[2]

The user's password is restricted to a maximum of fourteen characters.^{[Notes 1]}
The user’s password is converted to uppercase.
The user's password is encoded in the System OEM code page.^[3]
This password is NULL-padded to 14 bytes.^[4]
The “fixed-length” password is split into two 7-byte halves.
These values are used to create two DES keys, one from each 7-byte half, by converting the seven bytes into a bit stream with the most significant bit first, and inserting a null bit after every seven bits (so 1010100 becomes 10101000). This generates the 64 bits needed for a DES key. (A DES key ostensibly consists of 64 bits; however, only 56 of these are actually used by the algorithm. The null bits added in this step are later discarded.)
Each of the two keys is used to DES-encrypt the constant ASCII string “KGS!@#$%”,^{[Notes 2]} resulting in two 8-byte ciphertext values. The DES CipherMode should be set to ECB, and PaddingMode should be set to NONE.
These two ciphertext values are concatenated to form a 16-byte value, which is the LM hash.

Security weaknesses[edit]

LAN Manager authentication uses a particularly weak method of hashing a user's password known as the LM hash algorithm, stemming from the mid 1980s when viruses transmitted by floppy disks were the major concern.^[5] Although it is based on DES, a well-studied block cipher, the LM hash has several weaknesses in its design.^[6]This makes such hashes crackable in a matter of seconds using rainbow tables, or in a few minutes using brute force. Starting with Windows NT, it was replaced by NTLM, which is still vulnerable to rainbow tables, and brute force attacks unless long, unpredictable passwords are used, see password cracking. NTLM is used for logon with local accounts except on domain controllers since Windows Vista and later versions no longer maintain the LM hash by default.^[5]Kerberos is used in Active Directory Environments.

The major weaknesses of LAN Manager authentication protocol are:^[7]

Password length is limited to a maximum of 14 characters chosen from the 95 ASCII printable characters.
Passwords are not case sensitive. All passwords are converted into uppercase before generating the hash value. Hence LM hash treats PassWord, password, PaSsWoRd, PASSword and other similar combinations same as PASSWORD. This practice effectively reduces the LM hash key space to 69 characters.
A 14-character password is broken into 7+7 characters and the hash is calculated for each half separately. This way of calculating the hash makes it dramatically easier to crack, as the attacker only needs to brute-force 7 characters twice instead of the full 14 characters. This makes the effective strength of a 14-character password equal to only ${displaystyle 69^{7}approx 2^{43}}$ , or twice that of a 7-character password, which is 3.7 trillion times less complex than the ${displaystyle 69^{14}approx 2^{86}}$ theoretical strength of a 14-character single-case password. As of 2020, a computer equipped with a high-end graphics processor (GPUs) can compute 40 billion LM-hashes per second.^[8] At that rate, all 7-character passwords from the 95-character set can be tested and broken in half an hour; all 7-character alphanumeric passwords can be tested and broken in 2 seconds.
If the password is 7 characters or less, then the second half of hash will always produce same constant value (0xAAD3B435B51404EE). Therefore, a password is less than or equal to 7 characters long can be identified visibly without using tools (though with high speed GPU attacks, this matters less).
The hash value is sent to network servers without salting, making it susceptible to man-in-the-middle attacks such as replay the hash. Without salt, time–memory tradeoffpre-computed dictionary attacks, such as a rainbow table, are feasible. In 2003, Ophcrack, an implementation of the rainbow table technique, was published. It specifically targets the weaknesses of LM encryption, and includes pre-computed data sufficient to crack virtually all alphanumeric LM hashes in a few seconds. Many cracking tools, such as RainbowCrack, Hashcat, L0phtCrack and Cain, now incorporate similar attacks and make cracking of LM hashes fast and trivial.

Workarounds[edit]

To address the security weaknesses inherent in LM encryption and authentication schemes, Microsoft introduced the NTLMv1 protocol in 1993 with Windows NT 3.1. For hashing, NTLM uses Unicode support, replacing LMhash=DESeach(DOSCHARSET(UPPERCASE(password)), 'KGS!@#$%') by NThash=MD4(UTF-16-LE(password)), which does not require any padding or truncating that would simplify the key. On the negative side, the same DES algorithm was used with only 56-bit encryption for the subsequent authentication steps, and there is still no salting. Furthermore, Windows machines were for many years configured by default to send and accept responses derived from both the LM hash and the NTLM hash, so the use of the NTLM hash provided no additional security while the weaker hash was still present. It also took time for artificial restrictions on password length in management tools such as User Manager to be lifted.

While LAN Manager is considered obsolete and current Windows operating systems use the stronger NTLMv2 or Kerberos authentication methods, Windows systems before Windows Vista/Windows Server 2008 enabled the LAN Manager hash by default for backward compatibility with legacy LAN Manager and Windows ME or earlier clients, or legacy NetBIOS-enabled applications. It has for many years been considered good security practice to disable the compromised LM and NTLMv1 authentication protocols where they aren't needed.^[9]Starting with Windows Vista and Windows Server 2008, Microsoft disabled the LM hash by default; the feature can be enabled for local accounts via a security policy setting, and for Active Directory accounts by applying the same setting via domain Group Policy. The same method can be used to turn the feature off in Windows 2000, Windows XP and NT.^[9] Users can also prevent a LM hash from being generated for their own password by using a password at least fifteen characters in length.^[4]--NTLM hashes have in turn become vulnerable in recent years to various attacks that effectively make them as weak today as LanMan hashes were back in 1998.^{[citation needed]}

Reasons for continued use of LM hash[edit]

Many legacy third party SMB implementations have taken considerable time to add support for the stronger protocols that Microsoft has created to replace LM hashing because the open source communities supporting these libraries first had to reverse engineer the newer protocols—Samba took 5 years to add NTLMv2 support, while JCIFS took 10 years.

Availability of NTLM protocols to replace LM authentication
Product	NTLMv1 support	NTLMv2 support
Windows NT 3.1	RTM (1993)	Not supported
Windows NT 3.5	RTM (1994)	Not supported
Windows NT 3.51	RTM (1995)	Not supported
Windows NT 4	RTM (1996)	Service Pack 4^[10] (25 October 1998)
Windows 95	Not supported	Directory services client (released with Windows 2000 Server, 17 February 2000)
Windows 98	RTM	Directory services client (released with Windows 2000 Server, 17 February 2000)
Windows 2000	RTM (17 February 2000)	RTM (17 February 2000)
Windows ME	RTM (14 September 2000)	Directory services client (released with Windows 2000 Server, 17 February 2000)
Samba	?	Version 3.0^[11] (24 September 2003)
JCIFS	Not supported	Version 1.3.0 (25 October 2008)^[12]
IBM AIX (SMBFS)	5.3 (2004)^[13]	Not supported as of v7.1^[14]

Poor patching regimes subsequent to software releases supporting the feature becoming available have contributed to some organisations continuing to use LM Hashing in their environments, even though the protocol is easily disabled in Active Directory itself.

Lastly, prior to the release of Windows Vista, many unattended build processes still used a DOS boot disk (instead of Windows PE) to start the installation of Windows using WINNT.EXE, something that requires LM hashing to be enabled for the legacy LAN Manager networking stack to work.

Notes[edit]

^If the password is more than fourteen characters long, the LM hash cannot be computed.
^The string “KGS!@#$%” could possibly mean Key of Glen and Steve and then the combination of Shift + 12345. Glen Zorn and Steve Cobb are the authors of RFC 2433 (Microsoft PPP CHAP Extensions).

References[edit]

^'Chapter 3 - Operating System Installation: The LMHash'. Microsoft Technet. Retrieved 2015-05-12.
^Glass, Eric (2006). 'The NTLM Authentication Protocol and Security Support Provider: The LM Response'. Retrieved 2015-05-12.
^'List of Localized MS Operating Systems'. Microsoft Developer Network. Retrieved 2015-05-12.
^ ^a^b'Cluster service account password must be set to 15 or more characters if the NoLMHash policy is enabled'. Microsoft. 2006-10-30. Retrieved 2015-05-12.
^ ^a^bJesper Johansson. 'The Most Misunderstood Windows Security Setting of All Time'. TechNet Magazine. Microsoft. Retrieved 2 November 2015. Although Windows Vista has not been released yet, it is worthwhile to point out some changes in this operating system related to these protocols. The most important change is that the LM protocol can no longer be used for inbound authentication—where Windows Vista is acting as the authentication server.
^Johansson, Jasper M. (2004-06-29). 'Windows Passwords: Everything You Need To Know'. Microsoft. Retrieved 2015-05-12.
^Rahul Kokcha
^Benchmark Hashcat v6.1.1 on RTX 2070S (SUPER), Mode 3000 LM, accessed November 29, 2020
^ ^a^b'How to prevent Windows from storing a LAN manager hash of your password in Active Directory and local SAM databases'. Microsoft Knowledge Base. 2007-12-03. Retrieved 2015-05-12.
^'Windows NT 4.0 Service Pack 4 Readme.txt File (40-bit)'. Microsoft. 1998-10-25. Retrieved 2015-05-12.
^'The Samba Team announces the first official release of Samba 3.0'. SAMBA. 2003-09-24. Retrieved 2015-05-12.
^'The Java CIFS Client Library'. Retrieved 2015-05-12.
^'AIX 5.3 Networks and communication management: Server Message Block file system'. IBM. 2010-03-15. p. 441. Retrieved 2015-05-12.
^'AIX 7.1 Networks and communication management: Server Message Block file system'. IBM. 2011-12-05. Retrieved 2015-05-12.

External links[edit]

Wikibooks has a book on the topic of: Reverse Engineering/Cracking Windows XP Passwords

'Microsoft LAN Manager'. Archived from the original on 2017-02-12.
Oechslin, Philippe (2003). 'Making a Faster Cryptanalytic Time-Memory Trade-Off'(PDF). Advances in Cryptology, CRYPTO 2003.
'Ophcrack, a well known password cracker'.
'Cain and Abel, password recovery tool for Microsoft Operating Systems'.
mudge (1997-07-24). 'A L0phtCrack Technical Rant'. Archived from the original on 2011-12-11.Alt URL

Retrieved from 'https://en.wikipedia.org/w/index.php?title=LAN_Manager&oldid=991965300#LM_hash_details'

What You Need for This Project

A Kali Linux machine, real or virtual
A Windows Server 2016 machine, real or virtual (or any other Windows version)

Creating a Windows Test User

On your Windows machine, click Start.

Type in CMD and press Shift+Ctrl+Enter.

If a 'User Account Control' box pops up,click Yes.

In the Administrator command prompt window,execute this command, which creates a user named'jose' with a password of 'P@ssw0rd'.

net user jose P@ssw0rd /add

The command succeeds, as shown below.

Downloading and Installing 7-Zip

In a browser, go to

Download the correct version for your operating system,which is probably the 64-bit version,as shown below.

Install itwith the default options.

Downloading and Installing Cain

In a browser, go to

Right-click the downloaded file, point to7-Zip, and click'Extract Here',as shown below.

Enter a password of samas shown below. Click OK.

Double-click the ca_setup file.Install the software with the default options,as shown below.

When you see the message below, asking whether toinstall WinPcap, click the'Don't install' button.

Troubleshooting

If you get a warning box saying'Found some malware', as shown below,you need to tell Windows Defender not toremove Cain.

At the lower left of the desktop, clickthe magnifying-glass 'Search' icon and typeDEFENDER. Open Windows Defender.

In Windows Defender, click Settings andturn off 'Real-time protection'as shown below.

Close Windows Defender and run the ca_setup fileagain.

If this is your personal machine, remember to turn'Real-time protection' back on when you completethe project.

Installing WinPcap

In a browser, go to

Click 'Installer for Windows',as shown below. Download and install thesoftware with the default options.

Extracting Password Hashes with Cain

On your Windows desktop, right-click the Cainicon and click 'Run as Administrator'.

If a 'User Account Control' box pops up,click Yes.

In Cain, on the upper set of tabs, clickCracker.

In Cain, move the mouse to the center of thewindow, over the empty white space.

Right-click and click 'Add to list...',as shown below.

In the 'Add NT Hashes from' box, accept thedefault selectionof 'Import Hashes from local system',as shown below,and click Next.

The password hashes appear,as shown below.

Understanding Password Hashes

There are two password hashes: LM Hashes and NT hashes.

LM hashes date from the 1980's, andare so weak Microsoftno longer uses them. The LM hash values Cainshows are just dummy filler values that no longerinclude any information about real passwords.

NT hashes are Microsoft's 'more secure' hash,used by Windows NT in 1993 and never updated inany way. As you will see, these hashes are alsovery weak and easily cracked, compared with Linuxpassword hashes.

Cracking four Linux hashes took about 20 secondsusing a dictionary of 500 words when I did it,but as you will see, you can crack four Windowspasswords using a dictionary of 500,000 wordsin about a second. Windows password hashesare more than 10,000 times weaker thanLinux hashes.

Notice that your NT passwordhash for 'Jose'starts with E19CC, just like mine, shown in theimage above. This isbecause Microsoft doesn't add a random 'salt'to passwords before hashing them--every useron every Windows machine on Earth has the same saltif they are using a password of P@ssw0rd.

That means you can often crack Windows passwordhashes by just Googling them,as shown below, because manylists of common passwords and hashes havebeen uploaded to the Internet over the last20 years.

However, in this project, we'll use hashcat, which is avery powerfulway to crack passwords.

Exporting the Hash to a Text File

In Cain, right-click jose and clickExport. Save the filewith the namewin1 in the default format (L0phtCrack 2.x file).

Open the win1.lc file in Notepad.

Carefully highlight the NT hash for Jose,as shown below, right-click it, and clickCopy.

12.1: Recording Your Success (5 pts.)

Use the formbelow to record your score in Canvas.

If you don't have a Canvas account, seethe instructionshere.

Pasting the Password Hash into Kali Linux

In your Kali Linux machine,in a Terminal window, execute these commands: In the nano window, from the menu bar at the top,click Edit, Paste.

The hash appears,as shown below:

Press Ctrl+X, Y, Enter tosave the file.

Getting a Wordlist

Kali Linux contains a list of approximately 500,000 commonlyused passwords from the RockYou breach.

In a Terminal window, execute these commands to extract them:

You should see the first ten passwords,as shown below.

Getting Hashcat 2.00

Hashcat updated to 3.00 and it won't run in a virtualmachine anymore. The simplest solution is to use theold version.

In a Terminal window, execute these commands:

You should see four password hashes,as shown below:

Cracking the Hashes