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See: POP3 APOP.

Malicious logic that activates when specified conditions are met. Usually intended to cause denial of service or otherwise damage system resources. (See: Trojan horse, virus, worm.)

A bit string or bit vector of finite length. (See: bit, block cipher. Compare: byte, word.)

An error in the design, implementation, or operation of an information system. A flaw may result in a vulnerability. (Compare: vulnerability.)

Synonym for either "certificate policy" or "certification practice statement".

The property that data is not disclosed to system entities unless they have been authorized to know the data. (See: Bell LaPadula model, classification, data confidentiality service, secret. Compare: privacy.)

A PKI architecture based on a certification hierarchy. (Compare: mesh PKI, trust file PKI.)

Adversaries may generate network traffic using a protocol and port pairing that are typically not associated. For example, HTTPS over port 8088 or port 587 as opposed to the traditional port 443. Adversaries may make changes to the standard port used by a protocol to bypass filtering or muddle analysis/parsing of network data.

A security policy to prevent conflict of interest caused by an entity (e.g., a consultant) interacting with competing firms. (See: Brewer Nash model.)

A prefix ("crypto ") that means "cryptographic".

To convert plaintext to ciphertext by means of a code.

Adversaries may use a connection proxy to direct network traffic between systems or act as an intermediary for network communications.

See: Language of Temporal Ordering Specification.

An end to end encryption system for computer data networks that was developed by the U.S. DoD in the 1980s to provide host to host data confidentiality service for datagrams at OSIRM Layer 3. [Weis] (Compare: CANEWARE, IPsec.)

See: secondary definition under "obstruction".

An integrated microcircuit (in MYK 8x series manufactured by Mykotronx, Inc.) that implements SKIPJACK, KEA, DSA, SHA, and basic mathematical functions needed to support asymmetric cryptography; has a non deterministic random number generator; and supports key escrow. (See: FORTEZZA. Compare: CLIPPER.)

the processes and tools designed and deployed to protect sensitive business information from modification, disruption, destruction, and inspection

An intrusion detection method that is based on rules that specify system events, sequences of events, or observable properties of a system that are believed to be symptomatic of security incidents. (See: IDS, misuse. Compare: anomaly detection.)

An IEEE committee developing security standards for LANs. (See: SILS.)

See: perfect forward secrecy.

Adversaries may perform software packing to conceal their code. Software packing is a method of compressing or encrypting an executable. Packing an executable changes the file signature in an attempt to avoid signature based detection. Most decompression techniques decompress the executable code in memory.

"A seller of goods, services, and/or other information who accepts payment for these items electronically." [SET2] A merchant may also provide electronic selling services and/or electronic delivery of items for sale. With SET, the merchant can offer its cardholders secure electronic interactions, but a merchant that accepts payment cards is required to have a relationship with an acquirer. [SET1, SET2]

Adversaries may move onto systems, such as those separated from the enterprise network, by copying malware to removable media which is inserted into the control systems environment. The adversary may rely on unknowing trusted third parties, such as suppliers or contractors with access privileges, to introduce the removable media. This technique enables initial access to target devices that never connect to untrusted networks, but are physically accessible.

See: end cryptographic unit.

Department of Defense.

A formal, mathematical, state transition model of confidentiality policy for multilevel secure computer systems [Bell]. (Compare: Biba model, Brewer Nash model.)

Adversaries may abuse Unix shell commands and scripts for execution. Unix shells are the underlying command prompts on Android and iOS devices. Unix shells can control every aspect of a system, with certain commands requiring elevated privileges that are only accessible if the device has been rooted or jailbroken.

Part 1 of the standard is a code of practice for how to secure an information system. Part 2 specifies the management framework, objectives, and control requirements for information security management systems. [BS7799] (See: ISO 17799.)

"Cryptography engineered into an equipment or system whose basic function is not cryptographic." [C4009]

Adversaries may employ a known asymmetric encryption algorithm to conceal command and control traffic, rather than relying on any inherent protections provided by a communication protocol. Asymmetric cryptography, also known as public key cryptography, uses a keypair per party: one public that can be freely distributed, and one private that should not be distributed. Due to how asymmetric algorithms work, the sender encrypts data with the receiver’s public key and the receiver decrypts the data with their private key. This ensures that only the intended recipient can read the encrypted data. Common public key encryption algorithms include RSA, ElGamal, and ECDSA.

The act or process by which a CA sets the values of a digital certificate's data fields and signs it. (See: issue.)

An algorithm that uses mathematical rules to deterministically produce a pseudorandom sequence of cryptographic key values.

See: Distributed Authentication Security Service.

Adversaries may manipulate physical process control within the industrial environment. Methods of manipulating control can include changes to set point values, tags, or other parameters. Adversaries may manipulate control systems devices or possibly leverage their own, to communicate with and command physical control processes. The duration of manipulation may be temporary or longer sustained, depending on operator detection.

See: Digital Signature Algorithm.

See: Network Layer Security Protocol

Abbreviation for "local area network" [R1983]. (See: [FP191].)

Adversaries may undermine security controls that will either warn users of untrusted activity or prevent execution of untrusted applications. Operating systems and security products may contain mechanisms to identify programs or websites as possessing some level of trust. Examples of such features include: an app being allowed to run because it is signed by a valid code signing certificate; an OS prompt alerting the user that an app came from an untrusted source; or getting an indication that you are about to connect to an untrusted site. The method adversaries use will depend on the specific mechanism they seek to subvert.

See: Internet Protocol Security Option.

See: cardholder certification authority.

A system that is in operation but will not be improved or expanded while a new system is being developed to supersede it.

To convert enciphered text to plain text by means of a cryptographic system.

Result of TRANSEC measures used to prevent interception of a communication.

See: computer emergency response team.

A system environment that meets at least one of the following two conditions: (a) Application developers (including maintainers) do not have sufficient clearance or authorization to provide an acceptable presumption that they have not introduced malicious logic. (b) Configuration control does not provide sufficient assurance that applications and the equipment are protected against the introduction of malicious logic prior to and during the operation of system applications. [NCS04] (See: "first law" under "Courtney's laws". Compare: closed security environment.)

A property of a TOE representing how well it provides security in the context of its actual or proposed operational use.

A mode of system operation wherein (a) two or more security levels of information are allowed to be handled concurrently within the same system when some users having access to the system have neither a security clearance nor need to know for some of the data handled by the system, but (b) separation of the users and the classified material on the basis, respectively, of clearance and classification level are not dependent only on operating system control (like they are in multilevel security mode). (See: /system operation/ under "mode", protection level.)

A 16 bit field that specifies a control and release marking in the security option (option type 130) of IP's datagram header format. The valid field values are alphanumeric digraphs assigned by the U.S. Government, as specified in RFC 791.

Issue a digital certificate and thus vouch for the truth, accuracy, and binding between data items in the certificate (e.g., "X.509 public key certificate"), such as the identity of the

See: key. Usage: Usually shortened to just "key".