Author: username872Subject: Event ID 1 stops logging, Sysmon 6.00/6.01
Posted: 14 March 2017 at 10:02pm
Hello,
We recently began piloting a large expansion of Sysmon and are testing v/6.00 and now 6.01 (to see if it fixed the issue), coming from V3.10.
We are testing against both Windows 7 and Windows 10 and recently noticed an issue on Windows 7 workstations. We are first removing Sysmon 3.10 as well as ensuring the Sysmon.exe and sysmondrv.sys are removed from C:\Windows\. After the uninstall of the old version we attempt to install 6.00/6.01 with the following parameters:
"Sysmon64.exe -accepteula -i *config filepath here*". Sysmon appears to successfuly install and validates our config file (we've also tested with defaults to confirm it's not our config causing the issue). Here's where things are strange... On Windows 10, everything is working perfectly as expected without a hiccup but on Windows 7 machines we now immediately receive a popup informing us that the sysmondrv.sys driver is not digitally signed and therefor unsupported by Windows 7. The only option at this point is to close the notice and return to the command prompt where Sysmon shows that it is running successfully. At this time, all events from Sysmon are logging correctly (We are using all events minus Image Loads) and see the data in event viewer and our SIEM accordingly.
The issue is that as soon as the workstation is rebooted, EventID 1 (Process creation) stops logging entirely, both on the host in event viewer and obviously subsequently in our SIEM. All other event types continue to to log correctly and we see them but creation events are not being generated. Restarts of the Sysmon service or more reboots of the host do not fix the issue. If we uninstall Sysmon and reinstall again, the process logging immediately returns but once again stops following a reboot.
Has anyone run into similar issues and if so, have you determined why the sysmondrv.sys driver is no longer signed for Windows 7 but appears to be signed/functioning for Windows 10? After hours of troubleshooting, our best guess is that this driver is the issue and to be honest it's driving us nuts!
Thanks!