Chapter 2 Flashcards
Agent
A malicious software program distributed by a hacker to take over control of a victim’s computers. Also known as a bot or a zombie. Agents are commonly used to construct botnets.
Annualized loss expectancy (ALE)
The calculation of the total loss potential across a year for a given asset and a specific threat. ALE calculations are part of risk assessment. ALE SLE ARO.
Annualized rate of occurrence (ARO)
A probability prediction based on statistics and historical occurrences on the likelihood of how many times in the next year is a threat going to cause harm. ARO is used in the ALE calculation.
Appliance firewall
A hardened hardware firewall.
Application layer (Layer 7)
The top or seventh layer of the OSI model. This layer is responsible for enabling communications with host software, including the operating system. The Application Layer is the interface between host software and the network protocol stack. The sub-protocols of this layer support specific applications or types of data.
Application firewall
A type of firewall that filters on a specific application’s content and session information.
Application gateway
A type of firewall that filters on a specific application’s content and session information.
Application proxy
A type of firewall that filters on a specific application’s content and session information.
Asset value (AV)
The cumulative value of an asset based on both tangible and intangible values. AV supports the SLE calculation.
Bastion host
A firewall positioned at the initial entry point where a network interfaces with the Internet. It serves as the first line of defense for the network. Also known as a sacrificial host.
Border sentry
A description often applied to firewalls positioned on network zone transitions or gateway locations.
Botnet
A network of zombie/bot/agent– compromised systems controlled by a hacker. The network consists of the bots, agents, or zombies that intercommunicate over the Internet.
Bots
Malicious software programs distributed by hackers to take over control of victims’ computers. Also known as agents or zombies. Bots are commonly used to construct botnets.
Bump-in-the-stack
A term for a firewall that is implemented via software.
Bump-in-the-wire
A term for a firewall that is a separate hardware implementation.
Circuit
A logical connection between a client and a resource server. May exist at Layer 3, 4, or 5 of the OSI model. Also known as a session or a state.
Circuit firewall
A filtering device that allows or denies the initial creation of a circuit, session, or state, but performs no subsequent filtering on the circuit once established.
Circuit proxy
A filtering device that allows or denies the initial creation of a circuit, session, or state, but performs no subsequent filtering on the circuit once established.
Closed source
A type of software product that is pre-compiled and whose source code is undisclosed.
Commercial firewall
A firewall product designed for larger networks. Usually a commercial firewall is a hardware device.
Content filtering
A form of filtering that focuses on traffic content. Application proxies perform most content filtering.
Cost/benefit analysis
The final equation of risk analysis to assess the relative benefit of a counter-measure against the potential annual loss of a given asset exposed to a specific threat.
Data link layer (Layer 2)
The second layer of the OSI model responsible for physical addressing (MAC addresses) and supporting the network topology, such as Ethernet.
Dead-man switch
A form of auto-initiation switch that triggers when the ongoing prevention mechanism fails. Common dead-man switches include firewalls and hand grenades. If the firewall stops functioning, the connection is severed. If a person dies while holding a live grenade, the safety latch opens and the grenade explodes.
De-encapsulation
The action of processing the contents of a header, removing that header, and sending the remaining payload up to the appropriate protocol in the next higher layer in the OSI model.
Dual-homed firewall
A firewall that has two network interfaces. Each network interface is located in a unique network segment. This allows for true isolation of the segments and forces the firewall to filter all traffic moving from one segment to another.
Dynamic packet filtering
The process of auto-matically created temporary filters. In most cases, the filters allow inbound responses to previous outbound requests. Also called stateful inspection.
Exposure factor
The potential amount of harm from a specific threat stated as a percentage. Used in the calculation of SLE.
Fail-safe/Fail-secure
A failure response resulting in a secured or safe level of access or communication.
Frame
The collection of data at the Data Link Layer (Layer 2) of the OSI model, defined by the Ethernet IEEE 802.3 standard, that consists of a payload from the Network Layer (Layer 3) to which an Ethernet header and footer have been attached.
Gateway
An entrance or exit point to a controlled space. A firewall is often positioned at a gateway of a network to block unwanted traffic.
Hardware address
The physical address assigned to a network interface by the manufacturer. Also known as the MAC address.