Many challenges to existing networks and infrastructure create big security holes and decrease security posture. In reality, several I.T. components give the entity more access than required. We have considerable security flaws with using I.P. addresses as a security anchor and static locations; the virtual private networks (VPN) and demilitarized zone (DMZ) architectures used to establish access are often configured to allow excessive implicit trust.  

##Challenge 1: The issue with a DMZ

The DMZ is the neutral network between the Internet and your organization’s private network. It’s protected by a front-end firewall that limits Internet traffic to specific systems within its zone. The DMZ can have a significant impact on security if not appropriately protected. Remote access technologies such as VPN or RDP, often located in the DMZ, have become common targets of cyberattacks. One of the main issues I see with the DMZ is that the bad actors know it’s there. It may be secured, but it’s visible.

##Challenge 2: The issue with the VPN

In basic terms, a VPN provides an encrypted server and hides your IP address. However, the VPN does not secure users when they land on a network segment and is based on coarse-grained access control where the user has access to entire network segments and subnets. Traditionally, once you are on a segment, there will be no intra-filtering on that segment. That means all users in that segment need the same security level and access to the same systems, but that is not always the case. 

##Challenge 3: permissive network access

VPNs generally provide broad, overly permissive network access with only fundamental access control limits based on subnet ranges. So, the traditional VPN provides overly permissive access and security based on I.P. subnets. Note: The issue with VLAN-based segmentation is large broadcast domains with free-for-all access. This represents a larger attack surface where lateral movements can take place. Below is a standard VLAN-based network running Spanning Tree Protocol ( STP ).

## Challenge 4: Security-based on trust

Much of the non-zero trust security architecture is based on trust, which bad actors abuse. On the other hand, examining a SASE overview includes zero trust networking and remote access as one of its components, which can adaptively offer the appropriate trust required at the time and nothing more. It is like providing a narrow segmentation based on many contextual parameters continuously assessed for risk to ensure the users are who they are and that the entities, either internal or external to the network, are doing what they are supposed to do.

**Removes excessive trust**

A core feature of SASE and Zero Trust is that it removes the excessive trust once required to allow entities to connect and collaborate. Within a zero-trust environment, our implicit trust in traditional networks is replaced with explicit identity-based trust with a default denial. With an identity-based trust solution, we are not just looking at IP addresses to determine trust levels. After all, they are just binary, deemed a secure private or a less trustworthy public. This assumption is where all of our problems started. They are just ones and zeros.

## Challenge 5: IP for Location and Identity 

To improve your security posture, it would be best to stop relying primarily on IP addresses and network locations as a proxy for trust. We have been doing this for decades. There is minimal context in placing a policy with legacy constructs. To determine the trust of a requesting party, we need to examine multiple contextual aspects, not just IP addresses.

And the contextual aspects are continuously assessed for security posture. This is a much better way to manage risk and allows you to look at the entire picture before deciding to enter the network or access a resource.

Example: Firewall Tagging

1) SASE: First attempt to 

Organizations have adopted different security technologies to combat these changes and include them in their security stack. Many of the security technologies are cloud-based services. Some of these services include the cloud-based secure web gateway (SWG), content delivery network [CDN], and web application firewall [WAF].

A secure web gateway (SWG) protects users from web-based threats and applies and enforces acceptable corporate use policies. A content delivery network (CDN) is a geographically distributed group of servers that works together to deliver Internet content quickly. A WAF, or web application firewall, helps protect web applications by filtering and monitoring HTTP traffic between them and the Internet.

The data center is the center of the universe.

However, even with these welcomed additions to security, the general trend was that the data center is still the center of most enterprise networks and network security architectures. Let’s face it: These designs are becoming ineffective and cumbersome with the rise of cloud and mobile technology. Traffic patterns have changed considerably, and so has the application logic.

2) SASE: Second attempt to

The next attempt was for a converged cloud-delivered secure access service edge (SASE) to accomplish this shift in the landscape. And that is what SASE architecture does. As you know, the SASE architecture relies on multiple contextual aspects to establish and adapt trust for application-level access. It does not concern itself with significant VLANs and broad-level access or believe that the data center is the center of the universe. Instead, the SASE architecture is often based on PoPs, where each PoP acts as the center of the universe.

The SASE definition and its components are a transformational architecture that can combat many of these discussed challenges. A SASE solution converges networking and security services into one unified, cloud-delivered solution that includes the following core capabilities of sase.

From the network side of things: SASE in networking:

1. 1. Software-defined wide area network (SD-WAN)
   2. Virtual private network (VPN)
   3. Zero Trust Network ZTN
   4. Quality of service (QoS)
   5. Software-defined perimeter (SDP)

Example SDP Technology: VPC Service Controls

From the security side of things, SASE capabilities in security:

1. 1. Firewall as a service (FWaaS)
   2. Domain Name System (DNS) security
   3. Threat prevention
   4. Secure web gateways
   5. Data loss prevention (DLP)
   6. Cloud access security broker (CASB)

Example Technology: The Web Security Scanner

SASE changes the focal point to the identity of the user and device. With traditional network design, we have the on-premises data center, considered the universe’s center. With SASE, that architecture changes this to match today’s environment and moves the perimeter to the actual user, devices, or PoP with some SASE designs. In contrast to traditional enterprise networks and security architectures, the internal data center is the focal point for access. 

Example Product: Cisco Meraki

### What is Cisco Meraki?

Cisco Meraki is a suite of cloud-managed IT solutions that include wireless, switching, security, EMM (Enterprise Mobility Management), and security cameras, all centrally managed from the web. The Meraki dashboard provides powerful and intuitive tools to manage your entire network from a single pane of glass. This holistic approach ensures that businesses can maintain robust security protocols without compromising on ease of management.

### Key Features of Cisco Meraki

#### Cloud-Based Management

One of the standout features of Cisco Meraki is its cloud-based management. This allows for real-time monitoring, configuration, and troubleshooting from anywhere in the world. With automatic updates and seamless scalability, businesses can ensure their network is always up-to-date and secure.

#### Advanced Security Features

Cisco Meraki offers a range of advanced security features designed to protect your network from various threats. These include intrusion detection and prevention systems (IDS/IPS), advanced malware protection (AMP), and content filtering. By leveraging these tools, businesses can safeguard their data and maintain the integrity of their network.

#### Simplified Deployment

Deploying a traditional network can be a complex and time-consuming task. Cisco Meraki simplifies this process with zero-touch provisioning, which allows devices to be pre-configured and managed remotely. This reduces the need for on-site technical expertise and accelerates the deployment process.

### Benefits of Using Cisco Meraki for Network Security

#### Centralized Control

The centralized control offered by the Meraki dashboard enables IT teams to manage multiple sites from a single interface. This not only streamlines operations but also ensures consistent security policies across all locations.

#### Scalability

As businesses grow, their network needs evolve. Cisco Meraki’s scalable solutions allow for easy expansion without the need for significant infrastructure changes. This flexibility ensures that businesses can adapt to changing demands without compromising on security.

#### Cost Efficiency

By reducing the need for on-site hardware and simplifying management, Cisco Meraki can lead to significant cost savings. Additionally, the reduced need for technical expertise can lower operational costs, making it an attractive option for businesses looking to optimize their IT budget.

VPN Security Scenario 

• Challenge: Traditional remote access VPNs

Remote access VPNs are primarily built to allow users outside the perimeter firewall to access resources inside the perimeter firewall. As a result, they often follow a hub-and-spoke architecture, with users connected by tunnels of various lengths depending on their distance from the data center. Traditional VPNs introduce a lot of complexity. For example, what do you do if you have multiple sites where users need to access applications? In this scenario, the cost of management would be high. 

• Challenge: Tunnel based on I.P

What’s happening here is that the tunnel creates an extension between the client device and the application location. The tunnel is based on IP addresses on the client device and the remote application. Now that there is I.P. connectivity between the client and the application, the network where the application is located is extended to the client.

However, the client might not sit in an insecure hotel room or from home. These may not be sufficiently protected, and such locations should be considered insecure. The traditional VPN has many issues to deal with. It is user-initiated, and policy often permits split-tunnel VPNs without Internet or cloud traffic inspection.

SASE: A zero-trust VPN solution

A SASE solution encompasses VPN services and enhances the capabilities of operating in cloud-based infrastructure to route traffic. On the other hand, with SASE, the client connects to the SASE PoP, which carries out security checks and forwards the request to the application. A SASE design still allows clients to access the application, but they can only access that specific application and nothing more, like a stripped-down VLAN known as a micro-segmentation.

Restricting Lateral Movements

Clients must pass security controls, and no broad-level access is susceptible to lateral movements. Access control is based on an allowlist rather than the traditional blocklist rule. Also, other variables present in the request context are used instead of using I.P. addresses as the client identifier. As a result, the application is now the access path, not the network.

Simplified Management & Policy Control

So, no matter what type of VPN services you use, the SASE provides a unified cloud to connect to instead of backhauling to a VPN gateway—simplifying management and policy control. Well-established technologies such as VPN, secure web gateway, and firewall are being reviewed and reassessed in Zero Trust remote access solutions as organizations revisit approaches that have been in place for over a decade. 

A recommendation: SASE and SD-WAN

The value of SD-WAN is high. However, it also brings many challenges, including new security risks. In some of my consultancies, I have seen unreliable performance and increased complexity due to the need for multiple overlays. Also, these overlays need to terminate somewhere, and this will be at a hub site.  However, when combined with SASE, the SD-WAN edge devices can be connected to a cloud-based infrastructure rather than the physical SD-WAN hubs. This brings the value of interconnectivity between branch sites without the complexity of deploying or managing physical Hub sites.

Zero Trust SASE: Vendor considerations

SASE features converge various individual components into one connected, cloud-delivered service, making it easy to control policies and behaviors. The SASE architecture is often based on a PoP design. When examining the SASE vendor, the vendor’s PoP layout should be geographically diverse, with worldwide entry and exit points. 

Also, considerations should be made regarding the vendor’s edge/physical infrastructure providers or colocation facilities. We can change your security posture, but we can’t change the speed of light and the laws of physics.

Consider how the SASE vendor routes traffic in their PoP fabric. Route optimization should be performed at each PoP. Some route optimizations are for high availability, while others are for performance. Does the vendor offer cold-potato or hot-potato routing? The cold-potato routing means bringing the end-user device into the provider’s network as soon as possible. On the other hand, “hot-potato routing” means the end user’s traffic traverses more of the public Internet.

The following is a list of considerations to review when discussing SASE with your preferred cybersecurity vendor:

A. Zero Trust SASE requirements: Information hiding:

Secure access service requires clients to be authenticated and authorized before accessing protected assets, regardless of whether the connection is inside or outside the network perimeter. Then, real-time encrypted connections are created between the requesting client and the protected asset. As a result, all SASE-protected servers and services are hidden from all unauthorized network queries and scan attempts.

You can’t attack what you can’t see.

The base for network security started by limiting visibility – you cannot attack what you cannot see. Public and private IP addresses range from separate networks. This was the biggest mistake we ever made as I.P. addresses are just binary, whether they are deemed public or private. If a host were assigned a public address and wanted to communicate with a host with a private address, it would need to go through a network address translation (NAT) device and have a permit policy set.

Understanding Port Knocking

Port knocking is a technique that enables secure and controlled access to network services. Traditionally, network ports are open and accessible, leaving systems vulnerable to unauthorized access. However, with port knocking, access to specific ports is only granted after a predefined sequence of connection attempts is made to other closed ports. This sequence acts as a virtual “knock” on the door, allowing authorized users to gain access while keeping malicious actors at bay.

To fully comprehend port knocking, let’s explore its inner mechanics. When users wish to access a specific service, they must first send connection attempts to a series of closed ports in a particular order. This sequence acts as a secret handshake, notifying the server that the user is authorized. Once the correct sequence is detected, the server dynamically opens the desired port, granting access to the requested service. It’s like having a hidden key that unlocks the door to a secure sanctuary.

Security based on the visibility

Network address translation is mapping an IP address space into another by modifying network address information in the IP header of packets while they are in transit across a traffic routing device. Limiting visibility this way works to a degree, but we cannot ignore the fact that a) if you have someone’s IP address, you can reach them, and b) if a port is open, you can potentially connect to it.

Therefore, the traditional security method can open your network wide for compromise, especially when bad actors have all the tools. However, finding, downloading, and running a port scanning tool is not hard.

“Nmap,” for Network Mapper, is the most widely used port scanning tool. Nmap works by checking a network for hosts and services. Once found, the software platform sends information to those hosts and services, responding. Nmap reads and interprets the response and uses the data to create a network map.

Example: Understanding Lynis

Lynis is an open-source security auditing tool for discovering vulnerabilities on Unix, Linux, and macOS systems. It comprehensively analyzes the system’s configuration and provides valuable insights into potential security weaknesses. By scanning the system against a vast database of known security issues, Lynis helps identify areas for improvement.

Lynis runs a series of tests and audits on the target system. It examines various aspects, including file permissions, system settings, available software packages, and network configurations. Lynis generates a detailed report highlighting any identified vulnerabilities or potential security gaps by analyzing these factors. This report becomes a valuable resource for system administrators and security professionals to take necessary actions and mitigate risks.

Example: Single Packet Authorization

Zero-trust network security hides information and infrastructure through lightweight protocols such as single-packet authorization (SPA). No internal IP addresses or DNS information is shown, creating an invisible network. As a result, we have zero visibility and connectivity, only establishing connectivity after clients prove they can be trusted to allow legitimate traffic. Now, we can have various protected assets hidden regardless of location: on-premise, public or private clouds, a DMZ, or a server on the internal LAN, in keeping with today’s hybrid environment.

Default-drop dynamic firewall

This approach mitigates denial-of-service attacks. Anything internet-facing is reachable on the public Internet and, therefore, susceptible to bandwidth and server denial-of-service attacks. The default-drop firewall is deployed, with no visible presence to unauthorized users. Only good packets are allowed. Single packet authorization (SPA) also provides for attack detection.

If a host receives anything other than a valid SPA packet or similar construct, it views that packet as part of a threat. The first packet to a service must be a valid SPA packet or similar security construct.

If it receives another packet type, it views this as an attack, which is helpful for bad packet detection. Therefore, SPA can determine an attack based on a single malicious packet, a highly effective way to detect network-based attacks. Thus, external network and cross-domain attacks are detected.

B. Zero Trust SASE architecture requirements: Mutually encrypted connections:

Transport Layer Security ( TLS ) is an encryption protocol that protects data when it moves between computers. When two computers send data, they agree to encrypt the information in a way they both understand. Transport layer security (TLS) was designed to provide mutual device authentication before enabling confidential communication over the public Internet. However, the standard TLS configuration validates that the client is connected to a trusted entity. So, typical TLS adoptions authenticate servers to clients, not clients to servers. 

Mutually encrypted connections

SASE uses the full TLS standard to provide mutual, two-way cryptographic authentication. Mutual TLS provides this and goes one step further to authenticate the client. Mutual TLS connections are set up between all components in the SASE architecture. Mutual Transport Layer Security (mTLS) establishes an encrypted TLS connection in which both parties use X. 509 digital certificates to authenticate each other.

MTLS can help mitigate the risk of moving services to the cloud and prevent malicious third parties from imitating genuine apps. This offers robust device and user authentication, as connections from unauthorized users and devices are mitigated. Secondly, forged certificates, which are attacks aimed at credential theft, are disallowed. This will reduce impersonation attacks, where a bad actor can forge a certificate from a compromised authority.

C. Need to know the access model: Zero Trust SASE architecture requirements

Thirdly, SASE employs a need-to-know access model. As a result, SASE permits the requesting client to view only the resources appropriate to the assigned policy. Users are associated with their devices, which are validated based on policy. Only connections to the specifically requested service are enabled, and no other connection is allowed to any other service. SASE provides additional information, such as who made the connection, from what device, and to what service.

This gives you complete visibility into all the established connections, which is hard to do without an IP-based solution. So now we have a contextual aspect of determining the level of risk. As a result, it makes forensics easier. The SASE architecture only accepts good packets; bad packets can be analyzed and tracked for forensic activities.

Key Point: Device validation

Secondly, it enforces device validation, which helps against threats from unauthorized devices. We can examine the requesting user and perform device validation. Device validation ensures that the machine runs on trusted hardware and is used by the appropriate user.

Finally, suppose a device becomes compromised. In that case, lateral movements are entirely locked down, as a user is only allowed access to the resource it is authorized to. Or they could be placed into a sandbox zone where human approval must intervene and assess the situation.

D. Dynamic access control: Zero Trust SASE architecture requirements

This traditional type of firewall is limited in scope as it cannot express or enforce rules based on identity information, which you can with zero trust identity. Attempting to model identity-centric control with the limitations of the 5-tuple, SASE can be used alongside traditional firewalls and take over the network access control enforcement that we try to do with conventional firewalls. SASE deploys a dynamic firewall that starts with one rule – deny all.

Then, requested communication is dynamically inserted into the firewall, providing an active firewall security policy instead of static configurations. For example, every packet hitting the firewall is inspected with a single packet authentication (SPA) and then quickly verified for a connection request. 

Key Point: Dynamic firewall

Once established, the firewall is closed again. Therefore, the firewall is dynamically opened only for a specific period. The connections made are not seen by rogues outside the network or the user domain within the network. Allows dynamic, membership-based enclaves that prevent network-based attacks.

The SASE dynamically binds users to devices, enabling those users to access protected resources by dynamically creating and removing firewall rules.  Access to protected resources is facilitated by dynamically creating and removing inbound and outbound access rules. Therefore, we now have more precise access control mechanisms and considerably reduced firewall rules.

**Micro perimeter**

Traditional applications were grouped into VLANs whether they offered similar services or not. Everything on that VLAN was reachable. The VLAN was a performance construct to break up broadcast domains, but it was pushed into the security world and never meant to be there. 

Its prime use was to increase performance. However, it was used for security in what we know as traditional zone-based networking. The segments in zone-based networks are too large and often have different devices with different security levels and requirements.

Key Points:

A. Logical-access boundary: SASE enables this by creating a logical access boundary encompassing a user and an application or set of applications. And that is it—nothing more and nothing less. Therefore, we have many virtual micro perimeters specific to the business instead of the traditional main inside/outside perimeter. Virtual perimeters allow you to grant access to the particular application, not the underlying network or subnet.

B. Reduce the attack surface: The smaller micro perimeters reduce the attack surface and limit the need for excessive access to all ports and protocols or all applications. These individualized “virtual perimeters” encompass only the user, the device, and the application. They are created and specific to the session and then closed again when it is over or if the risk level changes and the device or user needs to perform setup authentication.

C. Software-defined perimeter (SDP): SASE only grants access to the specific application at an application layer. The SDP part of SASE now controls which devices and applications can access distinctive services at an application level. Permitted by a policy granted by the SDP part of SASE, machines can only access particular hosts and services and cannot access network segments and subnets.

**Reduced: Broad Network Access**

Broad network access is eliminated, reducing the attack surface to an absolute minimum. SDP provides a fully encrypted application communication path. However, the binding application permits only authorized applications to communicate through the established encrypted tunnels, thus blocking all other applications from using them. This creates a dynamic perimeter around the application, including connected users and devices. Furthermore, it offers a narrow access path—reducing the attack surface to an absolute minimum.

E. Identity-driven access control: Zero Trust SASE architecture requirements

Traditional network solutions provide coarse-grained network segmentation based on someone’s IP address. However, someone’s IP address is not a good security hook and does not provide much information about user identity. SASE enables the creation of microsegmentation based on user-defined controls, allowing a 1-to-1 mapping, unlike with a VLAN, where there is the potential to see everything within that VLAN.

Identity-aware access: SASE provides adaptive, identity-aware, precision access for those seeking more precise access and session control to applications on-premises and in the cloud. Access policies are primarily based on user, device, and application identities. The procedure is applied independent of the user’s physical location or the device’s I.P. address, except where it prohibits it. This brings a lot more context to policy application. Therefore, if a bad actor gains access to one segment in the zone, they are prevented from compromising any other network resource.

Detecting Authentication Failures in Logs:

Syslog: Useful Security Technology

Syslog, short for System Logging Protocol, is a standard for message logging within computer systems. It collects various log entries from different sources and stores them in a centralized location. Syslog is a valuable resource for detecting security events as it captures information about system activities, errors, and warnings.

Auth.log is a specific type of log file that focuses on authentication-related events in Unix-based operating systems. It records user logins, failed login attempts, password changes, and other authentication activities. Analyzing auth.log can provide vital insights into potential security breaches, such as brute-force attacks or suspicious login patterns.

Now that we understand the importance of syslog and auth.log, let’s delve into some effective techniques for detecting security events in these files. One widely used approach is log monitoring, where automated tools analyze log entries in real time, flagging suspicious or malicious activities. Another technique is log correlation, which involves correlating events across multiple log sources to identify complex attack patterns.