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Heartbeat Stops Reporting Knocking PC Off Network

SophosNewby

Good morning all, I am beginning to have a serious issue with our PC's since moving over to Sophos Intercept X Advanced. I am beginning to have PC's stop sending their Heartbeat, Sophos Central shows the PC as no longer sending a heartbeat and I believe what happens is the system goes into a protected mode, preventing the PC from having any network access, actually preventing its IP so my network icon immediately changes from connected to no connection. Most of the time the PC's are bouncing back and resume sending the heartbeat without any intervention on my part.

However some are not bouncing back and left in this disconnected state until, I manually assign an IP address to get the heartbeat back then I can simply reset the network card back to DHCP. This is beginning to be a serious issue, as yesterday this happened to 3 PC's and today I just back from our other plant because of the same issue on another PC.

Any users experienced something similar? Intercept X is managed through Sophos Central as well we do have a Sophos XG firewall that ties everything together. I have reached out to Sophos support but in the meantime if anyone has some suggestions to possible look at, please let me know, I'm at a loss as to why this is happening, if it's a bug, I'm not sure.

Thank you



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  • FormerMember
    0 FormerMember in reply to SophosNewby

    yes - that is exactly what it does. The balance comes though on how much your prioritize that protection over network availability. With Isolation turned on - you will see service interruptions from time to time. 

  • 0 in reply to FormerMember

    Thank you, I do have my firewall LAN rule requiring an amber heartbeat so if it something is compromised and changes the status threshold, that should still provide me some sort of reliable security laterally but I shall see.

  • FormerMember
    0 FormerMember in reply to SophosNewby

    Think of it this way:

    SFOS will protect from infections spreading between network segments that have to transverse it to talk to each other.

    Isolation protects from infections spreading inside a network segment.

  • 0 in reply to FormerMember

    However just a quick note, in theory with device isolation, if the administrator acknowledges the device has gone into this red status, should that now allow the PC to resume communication after its status has been reviewed and deemed no threat? Is that not the purpose of reviewing an issue and then acknowledging it? Because on Sophos Central the device then changes from red status to green status, the software on the device changes from red to green but yet it still never recovers, seems to be a bug no?

  • FormerMember
    0 FormerMember in reply to SophosNewby

    Isolation only goes into effect when the Health on the machine is RED. So, once you complete the action that turns it to GREEN, the isolation will be removed on that machine. You can confirm in the registry: Computer\HKEY_LOCAL_MACHINE\SOFTWARE\WOW6432Node\Sophos\Health\Status
    The admin, health, service, and threat values are what you care about. 1 is good. 3 is red. So, you can check what the machine thinks it is.

    Since you have two layers that can be affecting network traffic you might be encountering a collision. So, endpoint turns RED, it isolates and reports to the SFOS that it has RED health. SFOS also blocks. If the SFOS is safeguarding the comms to the DHCP server too - this could be a problem. 

    Do you have local DHCP servers in each segment? Or are they all beyond the SFOS from the perspective of the clients? Like you have the DHCP server in segment A and all machines have to route through the SFOS to get there?

  • 0 in reply to FormerMember

    Everything on site is LOCAL, the XG being part of the local LAN network along with the DHCP server. XG is our gateway/firewall device, if it were removed the devices would simply not have a way out to the internet, that is it. Should this occur again with device isolation off I'll be sure to check the registry key status.

  • 0

    Do you already have V18.0 MR5 installed? There is a switch for Heartbeat switch. https://community.sophos.com/sophos-xg-firewall/f/discussions/127593/e-mail-notification-for-missing-heartbeat/468290#468290

    Try to set the same switch to a higher sec threshold and check. 

    __________________________________________________________________________________________________________________

  • 0 in reply to SophosNewby
    SophosNewby said:
    I have turned off Device Isolation to monitor over the next few days, I assumed it was necessary to have this enabled, in case of a PC possibly being compromised and then preventing any lateral movement through the network.

    I suggest you leave this enabled.This is a big security plus but of course this isolation knocks you out in such cases where you have trouble with endpoints getting isolated for no visible reason.

  • 0 in reply to LuCar Toni

    I am still on the latest 17 version, I have been hesitant to move up with all my remote staff at the moment and was afraid of something screwing up during the migration to V18. Thank you.

  • 0

    So it has been approx. 4 days with Device Isolation disabled and although I am getting the notifications regarding heartbeats not being reported, none of the devices have been prevented access to the network. Obviously there is an issue when Device Isolation is enabled and the device isolates itself, it never recovers from that state on it's own.

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