DNS tunneling is a technique that abuses the DNS protocol to tunnel data or commands between a compromised host and an attacker’s server. DNS tunneling can be used to establish a command and control channel, which allows the attacker to remotely control the malware or exfiltrate data from the infected host1

The traffic capture in the exhibit shows some signs of DNS tunneling. The source IP address is 10.1.7.2, which is likely an internal host behind a firewall. The destination IP address is 8.8.8.8, which is a public DNS resolver. The DNS queries are for subdomains of badsite.com, which is likely a malicious domain registered by the attacker. The subdomains have long and random names, such as 0x2a0x2a0x2a0x2a0x2a0x2a0x2a0x2a.badsite.com, which could be used to encode data or commands. The DNS responses have large sizes, such as 512 bytes, which could be used to carry data or commands back to the host2

A beacon is a type of network traffic that is sent from a compromised device to a command and control (C2) server, which is a remote system that controls the malicious activities of the device . A beacon is used to establish and maintain communication between the device and the C2 server, as well as to receive instructions or exfiltrate data .

A common characteristic of a beacon is that it is periodic, meaning that it is sent at regular intervals, such as every few minutes or hours . This helps the C2 server to monitor the status and availability of the device, as well as to avoid detection by network security tools .

Another common characteristic of a beacon is that it is small and identically sized, meaning that it contains minimal or fixed amount of data, such as a simple acknowledgment or a random string . This helps the device to conserve bandwidth and resources, as well as to avoid detection by network security tools .

 This is because this URI specifies the exact attribute that contains the number of access rejects from the RADIUS server, which is the information that the NAE script needs to monitor and trigger an alert.

A. /rest/v1/system/vrfs/mgmt/radius/servers/cp.acnsxtest.local/2083/tcp?attributes=authstatistics. This is not the correct URI because it returns the entire authstatistics object, which contains more information than the access rejects, such as access accepts, challenges, timeouts, etc. This might make the NAE script more complex and inefficient to parse and process the data.

B. /rest/v1/system/vrfs/mgmt/radius/servers/cp.acnsxtest.local/2083/tcp?attributes=authstatistics?attributes=access_rejects. This is not a valid URI because it has two question marks, which is a syntax error. The question mark is used to indicate the start of the query string, which can have one or more parameters separated by ampersands. The correct way to specify multiple attributes is to use a comma-separated list after the question mark, such as ?attributes=attr1,attr2,attr3.

C. /rest/v1/system/vrfs/mgmt/radius/_servers/cp.acnsxtest.local/2083/tcp. This is not a valid URI because it has an extra underscore before servers, which is a typo. The correct resource name is servers, not _servers. Moreover, this URI does not specify any attributes, which means it will return the default attributes of the RADIUS server object, such as name, port, protocol, etc., but not the authstatistics or access_rejects.

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Rules 6 and 7 in the “medical-mobile” policy are used to deny access to the WLAN for a period of time if the clients send any SSH or Telnet traffic, as required by the scenario. However, these rules are currently placed below rule 5, which permits access to the Internet for any traffic. This means that rule 5 will override rules 6 and 7, and the clients will not be denied access to the WLAN even if they send SSH or Telnet traffic.

To fix this issue, rules 6 and 7 should be moved to the top of the list, before rule 5. This way, rules 6 and 7 will take precedence over rule 5, and the clients will be denied access to the WLAN if they send SSH or Telnet traffic, as expected.

Alert duration and threshold settings are used to control how often and under what conditions email notifications are sent for gateway IDS/IPS events 1. By adjusting these settings, the customer can reduce the frequency of repeat email notifications for the same threat, while still being informed of any critical or new threats.

To adjust the alert duration and threshold settings in Aruba Central, the customer can follow these steps 1:

• In the Aruba Central app, set the filter to Global, a group, or a device.
• Under Analyze, click Alerts & Events.
• Click the Config icon to open the Alert Severities & Notifications page.
• Select the Gateway IDS/IPS tab to view the alert categories and severities for gateway IDS/IPS events.
• Click on an alert category to expand it and view the alert duration and threshold settings for each severity level.
• Enter a value in minutes for the alert duration. This is the time period during which the alert is active and email notifications are sent.
• Enter a value for the alert threshold. This is the number of times the alert must be triggered within the alert duration before an email notification is sent.
• Click Save.

By increasing the alert duration and/or threshold values, the customer can reduce the number of email notifications for recurring threats, as they will only be sent when the threshold is reached within the duration. For example, if the customer sets the alert duration to 60 minutes and the alert threshold to 10 for a Critical severity level, then an email notification will only be sent if the same threat occurs 10 times or more within an hour.

The correct answer is B. Create a new VLAN on the AOS-CX switch and configure that VLAN as the UBT client VLAN.

User-based tunneling (UBT) is a feature that allows the AOS-CX switches to tunnel the traffic from wired clients to a mobility gateway cluster, where they can be assigned a role and a VLAN based on their authentication and authorization 1. To enable UBT, the switches need to have a UBT zone configured with the IP addresses of the gateways, and a UBT client VLAN configured with the ubt-client-vlan command 2.

The UBT client VLAN is a special VLAN that is used to encapsulate the traffic from the tunneled clients before sending it to the gateways. The UBT client VLAN must be different from any other VLANs used on the switch or the network, and it must not be assigned to any ports or interfaces on the switch 2. The UBT client VLAN is only used internally by the switch for UBT, and it is not visible to the clients or the gateways.

In this scenario, the customer wants to tunnel the clients that pass user authentication to the gateway cluster, where they will be assigned to VLAN 20. Therefore, the switch must have a UBT client VLAN configured that is different from VLAN 20 or any other VLANs on the network. For example, the switch can use VLAN 4000 as the UBT client VLAN, as shown in one of the web search results 3. The switch must also have a UBT zone configured with the system IP addresses of the gateways as the primary and backup controllers, as explained in question 3.

The other options are not correct or relevant for this issue:

• Option A is not correct because assigning VLAN 20 as the access VLAN on any edge ports to which tunneled clients might connect would conflict with UBT. The access VLAN is the VLAN that is assigned to untagged traffic on a port, and it is used for local switching on the switch 4. If VLAN 20 is assigned as the access VLAN, then the traffic from the clients will not be tunneled to the gateways, but rather switched locally on VLAN 20. This would defeat the purpose of UBT and cause inconsistency in role and VLAN assignment.
• Option C is not correct because VIA licenses are not required for UBT. VIA licenses are required for enabling VPN services on Aruba Mobility Controllers for remote access clients using Aruba Virtual Intranet Access (VIA) software . VIA licenses are not related to UBT or wired clients.
• Option D is not correct because changing the port-access auth-mode mode to client-mode on any edge ports to which tunneled clients might connect would not affect UBT. The port-access auth-mode mode determines how a port handles authentication requests from multiple clients connected to a single port . Client-mode is the default mode that allows only one client per port, while multi-client-mode allows multiple clients per port. The port-access auth-mode mode does not affect how UBT works or how traffic is tunneled from a port.

AppRF and WebCC are features that allow the MCs to classify and control application traffic and web content based on predefined or custom categories 12. These features are required to meet the scenario requirements of denying access to all high-risk websites and denying access to the WLAN for a period of time if they send any SSH or Telnet traffic.

To enable AppRF and WebCC, you need to check the following settings:

• On the global level, you need to enable AppRF and WebCC under Configuration > Services > AppRF and Configuration > Services > WebCC, respectively 12.
• On the role level, you need to enable AppRF and WebCC under Configuration > Security > Access Control > Roles > medical-mobile > AppRF and Configuration > Security > Access Control > Roles > medical-mobile > WebCC, respectively 12.
• You also need to make sure that the MCs have valid licenses for AppRF and WebCC, which are included in the ArubaOS PEFNG license 3.

ClearPass Policy Manager (CPPM) requires network device entries for the devices that communicate with it using RADIUS or TACACS+ protocols. In this scenario, the gateways are the devices that act as RADIUS clients and send authentication requests to CPPM for the WLAN users. Therefore, CPPM needs to have network device entries for the gateways’ actual IP addresses and the shared secrets that match the ones configured on the gateways.

Additionally, CPPM also requires network device entries for the gateways’ dynamic authorization VRRP addresses, which are used for sending CoA messages to the gateways. CoA messages are used to change the attributes or status of a user session on the gateways without requiring re-authentication. For example, CPPM can use CoA to apply policies, roles, or bandwidth limits based on various conditions. To enable VRRP IP addresses for dynamic authorization, you need to set up gateway clusters manually and assign a VRRP VLAN and a VRRP IP address to each cluster. This way, CPPM can use the VRRP IP address as the NAS IP address for RADIUS communications and CoA messages. The VRRP IP address will remain the same even if the active gateway in the cluster changes due to a failover event, ensuring seamless operations.

This is because ARP inspection is a security feature that validates ARP packets in a network and prevents ARP poisoning attacks12 ARP inspection works by intercepting, logging, and discarding ARP packets with invalid IP-to-MAC address bindings1 To enable ARP inspection, the switch needs to know which ports are trusted and which are untrusted. Trusted ports are those that connect to authorized DHCP servers or other network devices that are not vulnerable to ARP spoofing. Untrusted ports are those that connect to end hosts or devices that might send forged ARP packets13

In the exhibit, LAG 1 is configured as a trusted port for ARP inspection, which is correct because it connects to the core switch. However, the edge ports (1/1/1-1/1/24) are not configured as untrusted ports for ARP inspection, which is incorrect because they connect to end hosts that might be compromised by an attacker. By default, all ports are untrusted for ARP inspection, but this can be changed by using the command ip arp inspection trust on the interface configuration mode3 Therefore, to protect VLAN 4 against ARP poisoning, the edge ports should be configured as untrusted for ARP inspection by using the command no ip arp inspection trust on the interface configuration mode. This way, the switch will validate the ARP packets received on these ports against the DHCP snooping database or an ARP access-list and drop any invalid packets34

A. ARP proxy is not enabled on VLAN 4. This is not an issue because ARP proxy is an optional feature that allows the switch to respond to ARP requests on behalf of hosts in different subnets5 It is not related to ARP poisoning or ARP inspection.

B. LAG 1 is configured as trusted for ARP inspection but should be untrusted. This is not an issue because LAG 1 connects to the core switch, which is a trusted device that does not send forged ARP packets.

C. DHCP snooping is not enabled on VLAN 4. This is not an issue because DHCP snooping is a separate feature that prevents rogue DHCP servers from offering IP addresses to clients6 It is not directly related to ARP poisoning or ARP inspection, although it can provide information for ARP inspection validation if enabled

To configure user-based tunneling (UBT) on an AOS-CX switch, you need to specify the IP addresses of the mobility gateways that will receive the tunneled traffic from the switch 1. The primary controller is the preferred gateway for the switch to establish a tunnel, and the backup controller is the alternative gateway in case the primary controller fails or becomes unreachable 1. The IP addresses of the gateways should be their system IP addresses, which are used for inter-controller communication and cluster discovery 2.

In this scenario, the customer has a gateway cluster with two gateways, each with a system IP address on VLAN 4085. Therefore, the switch should use these system IP addresses as the primary and backup controllers for UBT. The IP addresses of the gateways on VLAN 20 and VLAN 4094 are not relevant for UBT, as they are used for user traffic and WAN connectivity, respectively 2. The VRRP IP address on VLAN 20 is also not applicable for UBT, as it is a virtual IP address that is not associated with any specific gateway 3.

Therefore, the best option is to use 10.20.4.21 as the primary controller and 10.20.4.22 as the backup controller for UBT on the switch. This will ensure high availability and cluster discovery for the tunneled traffic from the switch to the gateway cluster 12.

The UBT solution requires that the edge ports on the switches are configured in VLAN trunk mode, not access mode. This is because the UBT solution uses a special VLAN (VLAN 4095 by default) to encapsulate the user traffic and tunnel it to the gateway. The edge ports need to allow this VLAN as well as any other VLANs that are used for management or control traffic. Therefore, the edge ports should be configured as VLAN trunk ports and allow the necessary VLANs1

MPSK (Multi Pre-Shared Key) is a feature that allows assigning different pre-shared keys (PSKs) to different devices or groups of devices on the same WLAN. MPSK improves security over WPA2 in personal mode, which uses a single PSK for all devices on the WLAN. With MPSK, you can create and manage multiple PSKs, each with its own role, policy, and expiration date. You can also revoke or change a PSK for a specific device or group without affecting other devices on the WLAN. MPSK is compatible with devices that support WPA2 in personal mode only, as they do not need to support any additional protocols or certificates.

To use MPSK on the WLAN to which the devices connect, you need to enable MPSK in the WLAN settings and configure the PSKs in Aruba ClearPass Policy Manager (CPPM). You can find more information about how to configure MPSK in the [Configuring Multi Pre-Shared Key - Aruba] page and the [ClearPass Policy Manager User Guide] . The other options are not correct because they either do not improve security or are not applicable for devices that support WPA2 in personal mode only. For example, configuring WIDS policies that apply extra monitoring to these particular devices would not prevent them from being compromised or spoofed, but rather detect and mitigate potential attacks. Connecting these devices to the same WLAN to which 802.1X-capable clients connect, using MAC-Auth fallback, would not provide strong authentication or encryption, as MAC addresses can be easily spoofed or captured. Enabling dynamic authorization (RFC 3576) in the AAA profile for the devices would not affect the authentication process, but rather allow CPPM to change the attributes or status of a user session on the controller without requiring re-authentication.

The exhibit shows a screenshot of a certificate that has the following information:

• The subject common name (CN) is *.clearpass.local, which is a wildcard domain name that matches any subdomain under clearpass.local.
• The subject alternative names (SANs) are DNS Name=clearpass.local and DNS Name=*.clearpass.local, which are the same as the subject CN.
• The issuer CN is clearpass.local, which is the same as the subject domain name.
• The key usage (KU) is Digital Signature and Key Encipherment, which are required for RADIUS/EAP and RadSec usages.
• The extended key usage (EKU) is Server Authentication and Client Authentication, which are also required for RADIUS/EAP and RadSec usages.

The issue with this certificate is that it uses a fully qualified the ‘.local’ domain name, which is a reserved domain name for local networks that cannot be registered on the public Internet. This means that the certificate cannot be verified by any public certificate authority (CA), and therefore cannot be trusted by any external devices or servers that communicate with ClearPass. This could cause problems for RADIUS/EAP and RadSec usages, as they rely on secure and authenticated connections between ClearPass and other devices or servers.

To avoid this issue, the certificate should use a valid domain name that can be registered on the public Internet, such as clearpass.com or clearpass.net. This way, the certificate can be issued by a public CA that is trusted by most devices and servers, and can be verified by them. Alternatively, if the certificate is intended to be used only within a private network, it should be issued by a private CA that is trusted by all devices and servers within that network.