Exam CAS-004 topic 1 question 17 discussion

So we know IMAP rule works on port 143 with rule 58. Then we know then that A. and C. don't apply. The IP is not being blocked. Also a UTM certificate does not apply to this question. So that leaves B and D. We would need a certificate for IMAPS on port 993 but we also need a firewall rule for 993. Is rule 19 with destination to Any good enough or do we need to specify the IP, 15.22.33.45? If the rule is good enough then we don't need to create another rule and that means that the email server needs a certificate for TLS/SSl so it can use IMAPS/TCP 993. Therefore the answer has to be B.

TLS decryption enabled, client need to have UTM certificate

He is required to remove all non secure connections. He tested a theory by creating an IMAP rule (58) that now allows email. Meaning there was were no rules to allow either IMAP or IMAPS. He confirms that buy looking at the rules on the UTM. He cannot leave the unsecure connection he made with Rule 58 and must remove that. To get email working he has to put a rule in to allow IMAPS with port 993.

Key Observations from the UTM Firewall Rules: IMAP (port 143) is allowed in rule 58 (but this is an unencrypted protocol). IMAPS (secure IMAP, port 993) is missing from the rules, except in rule 19 which includes both 993 and 587. TLS decryption is enabled for rule 19 (which contains 993, the correct IMAPS port). If users can download email via IMAP (143) but not IMAPS (993), it’s likely a problem with the TLS decryption requirement. C) Make sure the UTM certificate is imported on the corporate computers. ✅ Since TLS decryption is enabled for rule 19 (which includes IMAPS port 993), the UTM is likely intercepting and inspecting encrypted traffic. If the UTM certificate is missing on client computers, their email clients will reject the connection due to an untrusted certificate. This explains why IMAP (143, unencrypted) works, but IMAPS (993, encrypted) does not.

Key Observations from the UTM Firewall Rules: IMAP (port 143) is allowed in rule 58 (but this is an unencrypted protocol). IMAPS (secure IMAP, port 993) is missing from the rules, except in rule 19 which includes both 993 and 587. TLS decryption is enabled for rule 19 (which contains 993, the correct IMAPS port). If users can download email via IMAP (143) but not IMAPS (993), it’s likely a problem with the TLS decryption requirement.C) Make sure the UTM certificate is imported on the corporate computers. ✅ Since TLS decryption is enabled for rule 19 (which includes IMAPS port 993), the UTM is likely intercepting and inspecting encrypted traffic. If the UTM certificate is missing on client computers, their email clients will reject the connection due to an untrusted certificate. This explains why IMAP (143, unencrypted) works, but IMAPS (993, encrypted) does not.

Ans is C. Importing the UTM certificate is essential for establishing a secure connection between the client and the email server when using IMAPS (which operates over port 993). If the UTM is performing SSL inspection or decryption, the client needs to trust the UTM's certificate to avoid connection issues. If the certificate is not trusted, the secure connection may fail, causing issues with downloading emails via IMAPS.

Source: Verifying each answer against Chat GPT, my experience, other test banks, a written book, and weighing in the discussion from all users to create a 100% accurate guide for myself before I take the exam. (It isn't easy because of the time needed, but it is doing my diligence)

I'm going to say B on this one. Not quite as confident as some of the other questions but here are my thoughts. A certificate is needed (or at least most of the time, depending on your configuration and needs) client side if the TLS decryption is happening at the application layer. This scenario is all networking layer dealing with VLANS, IPs, Ports and ACL's; therefore, a client-side certificate is not required to perform TLS decryption at the network edge like this. I'm going with B on this one.

I think the word "UTM" is the key here.

Given that the firewall rule (ID 19) already permits IMAPS traffic, the best action to ensure IMAPS functions properly is to confirm that the email server certificate is installed on the corporate computers. This will ensure that the clients can establish a secure connection using IMAPS

IMAPS uses port 993, which is on the last line. TLS decryption is enabled, meaning that the UTM is decrypting TLS traffic. The UTM is in-between the email server and the client. Let's look at why the other options are invalid. A: Users were able to download emails via IMAP, ruling this out. B: Line 1 reveals that the mail server is out on the Internet. The email server would have a public certificate signed by a trusted CA. There is no need to add the email server's certificate to the client computer's trusted root store. D: The last line exists and it is marked as active.

C) The UTM is doing break and inspect of IMAPS (TLS) traffic, therefore the UTMs certificate is required on the corporate users computers.

The question is formulated based on the fact that rule 19 is already in place to allow for IMAPS/993. The answer cannot be create a rule. Because of the UTM, and the SSL inspection, you will need a certificate installed on each client (corporate computers). So the answer is C. Make sure the UTM certificate is imported on the corporate computers.

IMAPS (Internet Message Access Protocol Secure) is a protocol that allows users to access and manipulate email messages on a remote mail server over a secure connection. IMAPS uses SSL/TLS encryption to protect the communication between the client and the server. IMAPS uses port 993 by default. To ensure IMAPS functions properly on the corporate user network, the security engineer should create an IMAPS firewall rule on the UTM (Unified Threat Management) device that allows traffic from VLAN 10 (Corporate Users) to VLAN 20 (Email Server) over port 993. The existing firewall rules do not allow this traffic, as they only allow HTTP (port 80), HTTPS (port 443), and SMTP (port 25). Reference: https://www.techopedia.com/definition/2460/internet-message-access-protocol-secure-imaps https://www.sophos.com/en-us/support/knowledgebase/115145.aspx

Based on the provided information, the security engineer should: D. Create an IMAPS firewall rule to ensure email is allowed. Explanation: The existing firewall rules are allowing traffic on ports 143, 80, 443, 990, 993, and 587, but there is no specific rule for IMAPS (port 993) on the corporate user network (VLAN 20). Rule 19 allows traffic on ports 993 and 587 from VLAN 20 to any destination and logs the traffic. However, Rule 21, which is intended for IMAPS (port 990) from VLAN 20 to a specific destination (15.22.33.45), is not active (No). To ensure IMAPS functions properly on the corporate user network (VLAN 20), the security engineer should create a specific IMAPS firewall rule that allows traffic on port 993 from VLAN 20 to the appropriate destination.

I'm inclined to go with D. I may be reading into the question a little too hard, but the question is prefaced with "The engineer formulates a theory and begins testing by creating the Firewall ID 58, and users are able to download emails correctly by using IMAP instead". Since that action was successful, wouldn't it make sense for the engineer to continue troubleshooting the firewall rules rather than moving on to troubleshooting certificates? CompTIA harps on their troubleshooting methodology and the engineer was at step 3, Test the theory to determine the cause. It seems likely that the engineer determined the cause was firewall rules when he created Rule 58 and IMAP worked. Wouldn't next best step be to see if creating an explicit rule specifying a destination of 15.22.33.45 would fix IMAPS despite the catch-all Rule 19? Then if that still doesn't fix things, move away from the networking layer and start troubleshooting certificates?

TLS Decryption is enabled for port 993, so clients need the UTM certificate.