Security Architecture Principles Flashcards
Definition: the practice of layering defenses to provide added protection.
defense in depth.
Many current security controls and architectures were developed with the concept of a security perimeter.
These models are network- or system-centric as opposed to data-centric.
The Internet perimeter should:
- Route traffic between the enterprise & Internet
- Prevent executable files from being transferred
- Monitor network ports for rogue activity
- Detect and block traffic from infected internal points
- Control user traffic bound toward the Internet
- ID and block potential attacks
- Eliminate threats such as spam, viruses and worms
- Enforce filtering policies
The perimeter should also provide protection for virtual private networks (VPNs):
- Terminate VPN traffic from remote users
- Provide a hub for terminating VPN traffic from remote sites
- Terminate traditional dial-in users
Modern IT architectures are usually ________ and __________.
decentralized and deperimeterized
As a consequence of decentralized and deperimeterized, both the number of potential attack ______ outside the organizational boundary and the number of attack ______ have grown.
targets and vectors .
Models of security architecture typically fall into two categories:
process models – flexibility
framework models – directive
the Zachman framework and the Sherwood Applied Business Security Architecture (SABSA) framework share a similar approach of developing a
who, what, why, where, when and how matrix
SABSA Security Architecture Matrix viewpoints
- contextual
- conceptual
- logical
- physical
- component
- operational
The Open Group Architecture Framework (TOGAF) objective is to ensure
- that architectural development projects meet business objectives,
- that they are systematic and
- that their results are repeatable.
In the Open Systems Interconnect (OSI) model for networks, each layer performs a specific function for the network:
Physical Layer—Manages signals
Data Link Layer–Divides data into frames > physical layer
Network Layer—Translates addresses & routes data Transport Layer—data transferred in the correct sequence
Session Layer— manages user connections
Presentation Layer–Formats, encrypts and compresses
Application Layer—Mediates between software applications and other layers of network services
TCP/IP
Transmission Control Protocol/Internet Protocol
The TCP/IP suite includes both _______ protocols and _______ protocols.
network-oriented and
application support
Name 3 types of defense in depth:
- Concentric rings (nested)
- Overlapping redundancy
- Segregation or compartmentalization
defense in depth is from an architectural perspective of:
Horizontal defense in depth - controls placed in path (functionally equivalent to concentric ring model)
Vertical defense in depth - controls placed in layers
A _______ is defined as a system or combination of systems that enforces a boundary between two or more networks. They control the most vulnerable point between a corporate network and the Internet, and they can be as simple or complex as the corporate information security policy demands.
firewall
There are many different types of firewalls, but most of them enable organizations to:
- Block access to particular sites.
- Limit traffic on an organization’s public services to relevant addresses and ports.
- Prevent certain users from accessing certain services.
- Monitor and record communications.
- Monitor and record communications to investigate or detect.
- Encrypt packets by creating a VPN over the Internet (e.g., IP security [IPSec], VPN tunnels). The capabilities of some firewalls can be extended so they can also provide for protection against viruses and attacks directed to exploit known operating system vulnerabilities.
Generally, the types of network firewalls fall into three categories:
- Packet filtering
- Application firewall systems
- Stateful inspection
Packet headers contain information, including the _____ and ______.
IP address of the sender and receiver, and the port numbers (application or service)
Packet filtering firewalls are therefore best suited for smaller networks, because the direct exchange of packets is permitted between outside systems and inside systems, the potential for an attack is determined by the total number of hosts and services.
True.
Advantages of packet filtering firewalls:
Simplicity of one network “choke point”
Minimal impact on network performance
Inexpensive or free
Disadvantages of packet filtering firewalls:
Vulnerable to attacks from improperly configured filters
Vulnerable to attacks tunneled over permitted services
All network systems vulnerable when a single packet filtering router is compromised
Some of the more common attacks against packet filter firewalls are:
- IP spoofing
- Source routing specification
- Miniature fragment attack
IP spoofing
In this type of attack, the attacker fakes the IP address of either an internal network host or a trusted network host. This enables the packet being sent to pass the rule base of the firewall and penetrate the system perimeter. If the spoofing uses an internal IP address, the firewall can be configured to drop the packet on the basis of packet flow direction analysis. However, attackers with access to a secure or trusted external IP address can spoof on that address, leaving the firewall architecture defenseless.
Source routing specification
This type of attack centers around the routing that an IP packet must take when it traverses the Internet from the source host to the destination host. In this process, it is possible to define the route so it bypasses the firewall. However, the attacker must know the IP address, subnet mask and default gateway settings to accomplish this. A clear defense against this attack is to examine each packet and drop packets whose source routing specification is enabled. Note that this countermeasure will not be effective if the topology permits a route that skips the choke point.
Miniature fragment attack
Using this method, an attacker fragments the IP packet into smaller ones and pushes it through the firewall. This is done with the hope that only the first sequence of fragmented packets will be examined, allowing the others to pass without review. This is possible only if the default setting is to pass residual packets. Miniature fragment attacks can be countered by configuring the firewall to drop all packets where IP fragmentation is enabled.
In contrast to packet filtering routers, application- and circuit-level gateways allow information to flow between systems but do not allow the direct exchange of packets. Therefore, application firewall systems provide greater protection capabilities than packet filtering routers. They work at the application level of the OSI model.
True
There are two types of application firewall systems:
- Application-level gateways—Application-level gateways are systems that analyze packets through a set of proxies—one for each service (e.g., Hypertext Transmission Protocol [HTTP] proxy for web traffic, FTP proxy). The implementation of multiple proxies, however, impacts network performance. When network performance is a concern, a circuit-level gateway may be a better choice.
- Circuit-level gateways—Commercially, circuit-level gateways are quite rare. Because they use one proxy server for all services, they are more efficient and also operate at the application level. There, TCP and UDP sessions are validated, typically through a single, general-purpose proxy before opening a connection. This differs from application-level gateways, which require a special proxy for each application-level service.
Both application firewall systems (Application-level gateways and Circuit-level gateways) employ the concept of bastion hosting in that they handle all incoming requests from the Internet to the corporate network, such as FTP or web requests. Bastion hosts are heavily fortified against attack.
True.
Application firewalls have the following advantages:
- Provide security for commonly used protocols
- Generally hide the network from outside untrusted networks
- Ability to protect the entire network by limiting break-ins to the firewall itself
- Ability to examine and secure program code
What is the disadvantage of application firewalls?
Poor performance and scalability as Internet usage grows.
A stateful inspection firewall, also referred to as dynamic packet filtering, tracks the destination IP address of each packet that leaves the organization’s internal network.
True.