MAC Address
MAC address is a physical address of Ethernet device which is a numeric value that uniquely identifies that network device.

MAC Address Spoofing
MAC Address spoofing, also known as MAC spoofing, refers to use other's MAC address to gain unauthorized access to a network. MAC spoofing attacks involve the use of a known MAC address of another host to attempt to make the target switch forward frames destined for the remote host to the network attacker.

MAC key
MAC key is the message authentication code(MAC) key used with Schannel protocols.

MAC duplication
MAC duplication is a type of denial of service (DoS) attack against switched networks.

MAC flooding
MAC flooding is a type of denial of service (DoS) attack against switched networks. Switches maintain a list (called a translation table) that maps individual MAC addresses on the network to the physical ports on the switch. In a typical MAC flooding attack, a switch is flooded with packets, each containing different source MAC addresses. The intention is to consume the limited memory set aside in the switch to store the MAC address-to-physical port translation table. The result of this attack causes the switch to enter a state called failopen mode, in which all incoming packets are broadcast out on all ports (as with a hub), instead of just down the correct port as per normal operation. A malicious user could then use a packet sniffer running in promiscuous mode to capture sensitive data from other computers (such as unencrypted passwords, e-mail and IM conversations), which would normally not be accessible, were the switch operating normally.

MAC spoofing
MAC spoofing, also known as MAC address spoofing, is an attack that involves spoofing the Media Access Control (MAC) address of legitimate hosts. MAC spoofing attacks involve the use of a known MAC address of another host to attempt to make the target switch forward frames destined for the remote host to the network attacker.

MAC: Mandatory Access Control
Mandatory Access Control(MAC) is where the system controls access to resources based on classification levels assigned to both the objects and the users.

MAC: Message Authentication Code
Message Authentication Code (MAC) is a short piece of cryptographic checksums used to authenticate a message. A MAC algorithm accepts as input a secret key and an arbitrary-length message to be authenticated, and outputs a MAC. The MAC value protects both a message's integrity as well as its authenticity, by allowing verifiers to detect any changes to the message content. It is also known as integrity check-values, modification detection codes, or message integrity codes.

Macro Virus
A macro virus is similar to a standard virus in all but its delivery. Rather than being code written in a programming language and attached to an executable, it is code written in a macro language and attached to a document.

Mafia Boy
Mafia Boy, in network security, refers to a teenager who brought down many of the largest sites on the Internet.

Mail Bomb
Mail bomb is a denial of service (DoS) attack on a user’s mailbox, which is the act of, or even incitement to, send massive amounts of probably meaningless text to a particular e-mail address. The purpose is to annoy the recipient, or even crash his/her system - and it is usually done in retaliation for some real or perceived offense.

Mail relaying
Mail relaying is a method used by spammers for sending junk mail, in which spammer is using other's machine to "relay" the emails and the machine sending the e-mail message is not the actual email sender. Spammers relay millions of e-mail messages through a mail relay to disguise the source of SPAM.

Malformed packet attack
Malformed packet attack refers to any attack that utilizes nonstandard packets to cause denial of service. These types of attacks generally exploit errors in the TCP/IP stack of the victim system by sending atypically formatted packets. If the system is vulnerable to the specific malformed packet, its subsequent crash can terminate network communications or shut down the system's operating system. In these types of attacks, the culprit may send out unusually large packets, fragmented packets that can't be reassembled properly, spoofed packets with unusual port numbers, or trash code targeted toward an open port. Some attacks combine a number of these exploits into one executable. Examples of malformed packet attacks include Ping of Death, TearDrop, NewTear, Bonk, Syndrop, Chargen, WinNuke, Land, and Jolt2.

Malformed URL attack
Malformed URL attack refers to an attack that utilizes a nonstandard Uniform Resource Locator (URL). Some software/hardware contains a flaw affecting the way that an URL is handled if it has a specific construction and its length is within a very narrow range of values. If such an URL were repeatedly sent to an affected system, a confluence of events could cause a memory allocation error that would result in the failure of the service.

Malicious Code
Malicious Code refers to software, such as Trojan horse or spyware, that appears to perform a useful or desirable function, but actually gains unauthorized access to system resources or tricks a user into executing other malicious logic.

Malware
Malware is a generic term for a number of different types of malicious code, such as spyware, virus, trojan horse etc.

Mangled Packet
Mangled Packet refers to an invalid packet in the ethernet and TCP/IP network. Instead of having its sound order or content, the packet is mangled or mis-ordered to confuse computers, firewalls, routers or any service present on the network or Internet. Notable software tools such as NMAP or Nessus can generate these types of mis-ordered / mangled packets to confuse and even shut down these devices. This is commonly associated with a type of network attack called a denial-of-service attack. Inadequate networks can be flooded with these types of network packets to confuse routers and computers. Sometimes, a mangled packet is used to open the network ajar and to see what other services are available when operators need to restart disabled devices.

Masquerade
Masquerade means disguise. In terms of communications security issues, a masquerade is a type of attack where the attacker pretends to be an authorized user of a system in order to gain access to it or to gain greater privileges than they are authorized for.

Masquerade Attack
Masquerade Attack is a type of attack in which one system entity illegitimately poses as another entity to gain access to confidential systems.

Master key
Master key is a key used by the client and server for generating session keys. The master key is used to generate the client-read key, the client-write key, the server-read key, and the server-write key. Master keys can be exported as simple key BLOBs.

MBSA: Microsoft Baseline Security Analyzer
Microsoft Baseline Security Analyzer (MBSA) is a tool designed for the IT professional that helps small- and medium-sized businesses determine their security state in accordance with Microsoft security recommendations and offers specific remediation guidance. MBSA can detect common security misconfigurations and missing security updates on Windows computer systems.

MD: Message digest
Message digest (MD) is a cryptographic checksum used to verify that an electronic message has not been modified in transit. Quite often, "message digest" is a phrase used to describe the "hash result" obtained as part of the process of providing secure messaging.

MD2: Message-Digest Algorithm 2
Message-Digest algorithm 2 (MD2) is an earlier, 8-bit version of MD5, an algorithm used to verify data integrity through the creation of a 128-bit message digest from data input that is claimed to be as unique to that specific data as a fingerprint is to the specific individual.

MD4: Message-Digest Algorithm 4
Message-Digest algorithm 4 (MD4) is an earlier version of MD5, an algorithm used to verify data integrity through the creation of a 128-bit message digest from data input that is claimed to be as unique to that specific data as a fingerprint is to the specific individual.

MD5: Message-Digest Algorithm 5
Message-Digest algorithm 5 (MD5) is a popular algorithm designed by Ronald Rivest in 1991 to replace an earlier hash function, MD4. MD5 is a widely-used cryptographic hash function with a 128-bit hash value. As an Internet standard (RFC 1321), MD5 has been employed in a wide variety of security applications, and is also commonly used to check the integrity of files. In 1996, a flaw was found with the design of MD5; while it was not a clearly fatal weakness, cryptographers began to recommend using other algorithms, such as SHA-1 (recent claims suggest that SHA-1 has been broken, however). In 2004, more serious flaws, making further use of the algorithm for security purposes questionable, were discovered.

MDC: Modification Detection Code
Modification Detection Code (MDC) is synonym for manipulation detection code that is a bit string, in cryptosystems, that is a function of data to which it is attached for the purpose of manipulation detection. The resulting message (data plus MDC) may then be encrypted to achieve secrecy or data authentication. The function used to generate the MDC must be public.

Melissa Virus
Melissa is a fast-spreading macro virus that is distributed as an e-mail attachment that, when opened, disables a number of safeguards in Word 97 or Word 2000, and, if the user has the Microsoft Outlook e-mail program, causes the virus to be resent to the first 50 people in each of the user's address books. While it does not destroy files or other resources, Melissa has the potential to disable corporate and other mail servers as the ripple of e-mail distribution becomes a much larger wave.

Message Digest
A 'message digest' is a commonly used phrase to describe the 'hash result' obtained as part of the process of providing secure messaging.

Message Integrity Code
Message Integrity Code(MIC) is a short piece of cryptographic checksum used to authenticate a message. It is also known as integrity check-values, modification detection code, or message authentication code.

Metasploit
The Metasploit Framework is an advanced open-source platform for developing, testing, and using exploit code. This project initially started off as a portable network game and has evolved into a powerful tool for penetration testing, exploit development, and vulnerability research. The Framework was written in the Perl scripting language and includes various components written in C, assembler, and Python. The widespread support for the Perl language allows the Framework to run on almost any Unix-like system under its default configuration. A customized Cygwin environment is provided for users of Windows-based operating systems. The project core is dual-licensed under the GPLv2 and Perl Artistic Licenses, allowing it to be used in both open-source and commercial projects.

MICR: Magnetic Ink Character Recognition
Magnetic Ink Character Recognition(MICR) is a technique that enables special characters printed in magnetic ink to be read and input rapidly to a computer. When a document that contains this ink needs to be read, it passes through a machine, which magnetizes the ink and then translates the magnetic information into characters. MICR is used to verify the legitimacy or originality of paper documents, especially checks. MICR is used extensively in banking because magnetic-ink characters are difficult to forge and are therefore ideal for marking and identifying cheques.

Microsoft Windows AntiSpyware
Microsoft Windows AntiSpyware, also known as Windows AntiSpyware, is a piece of software designed to remove, quarantine or prevent a spyware presence on Microsoft Windows 2000, Windows XP and Windows Server 2003 operating systems. It was first released in beta form by Microsoft on January 6, 2005. Antispyware definitions are released frequently by Mircrosoft.

Microsoft Security Notification Service
Microsoft Security Notification Service is a service provided by Microsoft that notifies customers about threats to Microsoft products and platforms.

Microsoft Security Toolkit
Microsoft Security Toolkit is a set of tools from Microsoft for helping customers protect their systems.

Microsoft Security Update
Microsoft Security Update is a service by Microsoft that notifies home and small business users about threats to Microsoft products and platforms.

Minutiae
In the biometric process of fingerscanning, minutiae is a specific point in a finger image. There are two main types, known as ridge endings and bifurcations. Sometimes, other details, such as the points at which scars begin or terminate, are considered minutiae

MITM: Man in the Middle Attack
Man-in-the-Middle Attack (MITM) is a type of attack where a user gets between the sender and receiver of information and sniffs any information being sent. The attacker, also known as the man in the middle, pretends to be the server to the client and the client to the server allowing him to decrypt data from both parties. In some cases, users may be sending unencrypted data, which means a man in-the-middle can easily obtain any unencrypted information. In other cases, a user may be only able to obtain the encrypted information from the attack and has to unencrypt the information before it can be read.

MMC: Microsoft Management Console
The Microsoft Management Console (MMC) is an application that provides a graphical-user interface (GUI) and a programming framework in which consoles (collections of administrative tools) can be created, saved, and opened. MMC was originally released as part of the Windows 98 Resource Kit, and is included on all later versions.

Mobile Phone Spam
Mobile phone spam, also known as SMS spam or cell phone spam, is any junk message delivered to a mobile phone as text messaging through the Short Message Service (SMS).

Modification Detection Code
Modification Detection Code is a short piece of cryptographic checksums used to authenticate a message. It is also known as integrity check-values, message integrity code, or message authentication code.

Modulus 10
Modulus 10, also known as LUHN formula, is a simple algorithm used to validate the number on a credit card. It works on cards issued by all the major credit card companies, including American Express, Visa, MasterCard, Discover, and Diner's Club. Originally created by a group of mathematicians in the 1960s, the LUHN formula is in the public domain, and anyone can use it.

MOE: Measures of Effectiveness
Measures of Effectiveness is a probability model based on engineering concepts that allows one to approximate the impact a give action will have on an environment. In Information warfare, it is the ability to attack or defend within an Internet environment.

Monoculture
Monoculture is the case where a large number of users run the same software, and are vulnerable to the same attacks.

Morris Worm
Morris Worm is a worm program written by Robert T. Morris, Jr. that flooded the ARPANET in November, 1988, causing problems for thousands of hosts.

MOSS: MIME Object Security Services
MIME Object Security Services (MOSS) is an email security scheme that applies end-to-end encryption and digital signature to MIME message content, using symmetric cryptography for encryption and asymmetric cryptography for key distribution and signature. MOSS never got widely implemented.

MPLS VPN
MPLS VPN is a technology that allows Service Providers to have complete control over parameters that are critical to offering its customers service guarantees with regard to bandwidth throughputs, latencies and availability. The technology enables secure Virtual Private Networks (VPN) to be built and allows scalability.

MPLS: Multiprotocol Label Switching
Multiprotocol Label Switching (MPLS), an architecture for fast packet switching and routing, provides the designation, routing, forwarding and switching of traffic flows through the network. MPLS is independent of the layer-2 and layer-3 protocols such as ATM and IP. MPLS provides a means to map IP addresses to simple, fixed-length labels used by different packet-forwarding and packet-switching technologies.

MPPE: Microsoft Point-to-Point Encryption
MPPE (Microsoft Point-to-Point Encryption) is a method of encrypting data transferred across Point-to-Point Protocol (PPP)-based dial-up connections or Point-to-Point Tunneling Protocol (PPTP) virtual private network (VPN) connections. MPPE uses the RSA algorithm for encryption and supports 40-bit and 128-bit session keys, which are changed frequently to ensure security. MPPE does not compress or expand data.

MPSA: Microsoft Personal Security Analyzer
Microsoft Personal Security Analyzer(MPSA) is a tool for identifying common security misconfigurations in Microsoft products, now supplanted by the Microsoft Baseline Security Analyzer (MBSA).

MS-CHAP: Microsoft Challenge Handshake Authentication Protocol
Microsoft Challenge Handshake Authentication Protocol (MS-CHAP) is a Microsoft's extensions to the Challenge-Handshake Authentication Protocol (CHAP) for it to support Microsoft operating systems.

MSRC: Microsoft Security Response Center
Microsoft Security Response Center is a team of security professionals at Microsoft responsible for responding to security threats involving Microsoft products.

MSSP: Managed Security Service Provider
A Managed security service provider (MSSP) is an Internet service provider (ISP) that provides an organization with some amount of network security management, which may include virus blocking, spam blocking, intrusion detection, firewalls, and virtual private network (VPN) management. An MSSP can also handle system changes, modifications, and upgrades.

Mstream
Mstream is a tool for launching distributed denial of service (DDoS) attacks.

Multicast
Multicast refers to send the same messages by one host to a selected group of hosts.

Multi-Factor Authentication
Multi-factor authentication consists of verifying and validating the authenticity of an identity using more than one validation mechanism

Multi-Homed
Multi-homed means a local area network or home network is directly connected to two or more ISP's.

Multi-Part Virus or Multipartite Virus
Multi-part virus is a hybrid virus, also called a multipartite virus. It combines characteristics of more than one type to infect both program files and system sectors. The virus may attack at either level and proceed to infect the other once it has established itself. Hybrid viruses can be very difficult to eradicate and, unless completely eradicated, will often reinfect the host system repeatedly.

Multiple Key Pairs
Multiple key pairs means assigning more than one public/private key pair to each user to solve a problem in key recovery. Two key pairs maybe used in the key recovery--one for signing messages to provide authentication and non-repudiation, and one for sending confidential messages.

Mutual SSL
Mutual SSL refers to a mutual authenticaion process by using the Secure Shell (SSL) protocol.

Mutual authentication
Mutual authentication or two-way authentication refers to two parties authenticating each other suitably. Technically, it refers to a client or user authenticating themselves to a server and that server authenticating itself to the user in such a way that both parties are assured of the others' identity. Typically, this is done for a client process and a server process without user interaction.

Multizone Network
Multizone network is a local area network with multiple segments each may serve different functions or for different departments.