This discussion has been locked.
You can no longer post new replies to this discussion. If you have a question you can start a new discussion

Sophos Firewall: v19.5 GA: Feedback and experiences

Release Post:  Sophos Firewall v19.5 is Now Available 

Old v19.0 MR1 thread:  Sophos Firewall: v19.0 MR1: Feedback and experiences 

EAP Sub thread:  SFOS v19.5 Early Access Program 

EAP 19.5 Thread:  Sophos Firewall: v19.5 EAP1: Feedback and experiences 



This thread was automatically locked due to age.

Top Replies

  • This is indeed expected behavior of the FCI feature.  What follows is a Draft of a KB Article I'm writing (feedback welcome).



    In XG 18.0 the DPI proxy was introduced, with many more SSL/TLS scanning options and certificate protection. There are some certificate security concerns with that are blocked in most configurations, however they are allowed without any warning when using DPI mode with the decryption profile "Maximum compatibility". In these cases the XG decrypts and re-signs, creating a new certificate with its own Certificate Authority that hides potential problems that the end user should know about which that would be blocked in other configurations.

    In 19.0 a new feature was added called Forward Certificate Invalidity (FCI). This feature detects certain types of certificate invalidity and "forwards" (tells the user) about them. Because we cannot create a certificate with the same error, so we create one in a special way that we know will cause browsers to warn users. A CA is used that us unique and untrusted, and the certificate Common Name is used as the error message to tell the end user what the problem is. This changes the behavior of DPI mode with Maximum Compatibility. By signing it in the way, browsers will warn users that there is a certificate problem but will allow users to proceed and load the pages as they did in 18.0/18.5.

    The most common issue that FCI catches on the public internet is websites that do not send their entire certificate chain. When a website provides their certificate, they usually provide the certificate, the CA that signed it (usually an intermediate CA), the CA that signed that one, up to the root CA. The root CA is trusted by the browser, and the browser can verify the entire chain.

    However some websites do not provide the chain. They may provide only the certificate, or they provide the certificate and the root CA, but they do not provide the intermediate CA. While this is valid, it is not best practice and sites like ssllabs.com which rate sites will cap their score.

    If a website does not provide the chain they usually implement AIA (Authority Information Access). This is a link within the certificate that says where to download the CA that signed it.

    Some browsers (Chrome 58+, Edge, Safari) will automatically use the AIA to download the intermediate and store it for future use. Firefox 75+ uses a different mechanism called intermediate CA preloading (wiki.mozilla.org/.../Intermediate_Preloading). Older Android (pre Oreo) devices do not support any mechanism. The XG does not currently support AIA.

    If the website does not provide the full chain, the XG behavior depends on the configuration. It is important to note that v19 did not introduce blocking of sites that do not provide the full chain. The XG has always blocked these sites when using normal security, and the resolution below has always worked. The difference is that when using a decryption profile that does not block self signed certificate, invalid issuers, or many other security concerns (such as "Maximum compatibility") we used to allow the connection and sign it in a way that made it appear more secure. Now we allow but sign it in a way that appears insecure.

    How to configure the system to allow access to sites that do not provide a complete certificate chain.

    Method 1 - Do not decrypt
    Configure the domain to not be decrypted. Adding the domain to the Local TLS Exclusion List is the best option for DPI mode. Adding it to a Web Exception will exclude it for both DPI and Proxy mode.

    Method 2 - Add the Intermediate certificate to the XG CA store

    Option 1:
    Test the site in www.ssllabs.com/.../
    You should see that the grade is capped to B and the Certification Path includes an "Extra Download". In the section under Issuer there should be an AIA link.

    Option 2:
    Use a browser that is not going through the XG, or is going through the XG with HTTPS not decrypted so that you get the original certificates as presented by the site. Ask the browser to display the certificate information and the AIA link should be there. How this is displayed is browser specific.

    Once you have the AIA link, download the certificate to your computer. Then in WebAdmin go to Certificates > Certificate Authorities and Add. Choose the file.
    With the Intermediate in the CA store, the page will load in all configurations.

    Jump to answer
  • I have updated 2 test firewalls to 19.5 today. Both have a tunnel to an XG with 19.0.1 and dynamic routing with OSPF. The first firewall has an IPSec tunnel, here the tunnel stood after the update, the OSPF negotiation basically worked (no error messages in the log), however the firewall did not distribute its own route, so the site was not reachable. Reboot and reconfigure OSPF did not help. After a rollback to 19.0.1 the OSPF worked again.
    The second firewall has a RED tunnel to the central office, there are no problems with OSPF there.
    Are there any known issues with SFOS 19.5, IPSec and OSPF?

    Ben

    If a post solves your question please use the 'Verify Answer' button.

  • Hi      Dev team would like to investigate why this is not working in your setup.Can you share the support access for your device/s in  Private message to me? Meanwhile some quick info on this  will help team to start with 1. config from /conf/routing/ 2. Logs: /log/csc.log , /log/ospfd.log , /log/zebra.log 3. ifconfig output 4. complete backup of the device config if available . Also If possible please provide device support access id for to login and check more. -Shrikant

  • Hi, I send you the access ID via PM. -Ben

    If a post solves your question please use the 'Verify Answer' button.

  • We had some downtime so we jumped back to 19.5 if you want to jump in firsthand and see the issues.

  • We had some downtime at the plant, so we jumped back to 19.5 If support wants to jump in first hand and see the issues. Hit me up via IM

  •   
    Hey Guys,  and I re-upgraded to 19.5 so we could do some testing and appy the above command. When we have all 4 tunnels up, the intended subnet doesn't get advertised to the expected peers. So we did the "no bgp network import-check", but it didn't resolve the issue. When we down one of the tunnels, I can see that the subnets then get advertised to the other tunnel that shares a peer with the tunnel that was shut down.

    Any additional tests we could perform?

  • Hello,

    i installed yesterday the firmware. After that i was faced with following issue:

    In SSL Inspection i habve 3 rules in the following order:

    1. Exclusions by website

    2. a rule with no decryption enabled from LAN with the Range of Smartphones to the internet

    3. a rule with decryption from LAN any devices to the internet

    Until yesterday everything worked perfectly. But now every device uses rule 3.  It seems that the order of the rules no longer matters. i had to define in rule 3 also a range with devices for decryption.

    I don't think that should be the case, right?

    Greets

    Andreas

  • Hi,

    this morning I was investigating the settings on both of my XGs and found that the Anti-virus and the anti-spam had not updated since the 19th. One is set for 4 hours and the other for 15 minutes.

    I initiated a manual update and both download anti-virus patterns dated the 20th November.

    Ian

    XG115W - v19.5.1 mr-1 - Home

    If a post solves your question please use the 'Verify Answer' button.

  • Hi,

    this morning I was investigating the settings on both of my XGs and found that the Anti-virus and the anti-spam had not updated since the 19th. One is set for 4 hours and the other for 15 minutes.

    I initiated a manual update and both download anti-virus patterns dated the 20th November.

    Ian

    XG115W - v19.5.1 mr-1 - Home

    If a post solves your question please use the 'Verify Answer' button.

  • Hi folks,

    further update. The XG with the 15 minute update schedule is not showing any new updates since the manual update at approx 1030 20/11 and the IPS data base has not updated since the 17th Nov 2022.

    Ian

    XG115W - v19.5.1 mr-1 - Home

    If a post solves your question please use the 'Verify Answer' button.