Troubleshooting [Admin]

VPN dashboard is not loading even though cs_vpn_indexes has data.

• Verify that the Splunk CIM is installed and the Authentication data model is accelerated.

• Verify that the CIM Authentication data model does not filter the VPN index (check the macro definition for cim_Authentication_indexes).

FortiGate VPN data:

• If you already have FortiGate VPN data ingested into Splunk, but you are unable to populate the VPN dashboard.

• Follow the instructions under the Data Onboarding > FortiGate VPN Logs section.

Windows machines are not generating events about firewall changes.

In other words, Windows machines are not generating WinEventLog Event ID 4950.

• Verify that the policy changes audit is enabled on your Windows machine.

• If not, execute the command below with Administrator rights to enable the policy (or you can do it with a group policy instead).

    auditpol.exe /set /category:"Policy Change" /subcategory:"MPSSVC rule-level Policy Change" /success:enable /failure:enable 
  

• Reference: https://www.eventsentry.com/kb/429

Windows firewall was disabled but the alert did not generate in the Cyences app.

• Verify that the Event is generated from a Windows machine through Event Viewer (search for Event ID 4950).

• If you can see the generated events on Event Viewer, then the next step would be to verify that you are collecting the WinEventLogs in XML format.

• If not, update the search query to:

    `cs_wineventlog_security` EventCode=4950 Type="Enable Windows Defender Firewall" Value=No | rename Changed_Profile AS ProfileChanged, Type AS SettingType, Value as SettingValue | table host, EventCode, ProfileChanged, SettingType, SettingValue 
    | `cs_windows_firewall_disabled_filter` 
  

Device Inventory dashboard does not display every device by default.

Refer to the App Installation and Configuration > Device Inventory > Backfill Device Inventory section for more information.

Sysmon data action field issue

• Due to a conflict in props.conf for both the Sysmon Add-on and Windows Add-on, the action field is displaying incorrect values for Sysmon related data.

• The correct value for the action field should be created, but instead we are receiving unknown as the value for every event coming from Sysmon EventCode=11.

• Ransomware related alerts will not work until this issue is resolved.

How to check whether the issue is present in your environment or not?

1. Execute the search below in the Cyences App (from Cyences’ navigation bar, click Search).

    | datamodel Endpoint Filesystem search strict_fields=false | search EventCode=11 | rename "Filesystem.tag" as tag, "Filesystem.action" as action
    | fields index, sourcetype, source, EventCode, EventDescription, action, tag, eventtype | table index, sourcetype, source, EventCode, EventDescription, action, tag, eventtype
   

2. Look for the action field in the table. The field value should be created. If not, follow the steps below to resolve the issue.

How to fix the problem?

1. From Splunk’s navigation bar, go to Settings > Data models.

2. Search for the Endpoint data model and click on it.

3. Click Edit > Edit Acceleration.

4. Uncheck the Accelerate box, then click Save.

5. Under Datasets, click Filesystem (on the left-hand side).

6. Under the Calculated fields section, click Edit for the action field.

1. Your current configuration should look similar to this:

    if(isnull(action) OR action="","unknown",action) 
   

2. Replace the above configuration/eval expression with the contents below:

    case((source="WinEventLog:Microsoft-Windows-Sysmon/Operational" OR source="XmlWinEventLog:Microsoft-Windows-Sysmon/Operational") AND EventCode=="1", "allowed", (source="WinEventLog:Microsoft-Windows-Sysmon/Operational" OR source="XmlWinEventLog:Microsoft-Windows-Sysmon/Operational") AND EventCode=="12" AND EventType=="CreateKey", "created", (source="WinEventLog:Microsoft-Windows-Sysmon/Operational" OR source="XmlWinEventLog:Microsoft-Windows-Sysmon/Operational") AND EventCode=="12" AND (EventType=="DeleteKey" OR EventType=="DeleteValue"), "deleted", (source="WinEventLog:Microsoft-Windows-Sysmon/Operational" OR source="XmlWinEventLog:Microsoft-Windows-Sysmon/Operational") AND EventCode=="13" AND EventType=="SetValue", "modified", (source="WinEventLog:Microsoft-Windows-Sysmon/Operational" OR source="XmlWinEventLog:Microsoft-Windows-Sysmon/Operational") AND EventCode=="11", "created", isnull(action) OR action="", "unknown", 1==1, action)
   

3. Click Save.

4. Click Edit > Edit Acceleration.

5. Check the Accelerate box, then click Save.

Reducing False Positives for the “Authentication - Bruteforce Attempt for a User” Alert

• We found false positives for this alert that are tied to sourcetype=linux:audit.

• This will continue to occur in environments where the Linux Auditd Technology Add-On (TA-linux_auditd) is being used.

How to check whether the issue is present in your environment or not?

1. Run the following search query and check the values present for the Type field:

    index=* `cs_authentication_indexes` action="failure" user="*" tag=authentication 
   

2. If the field contains a value named USER_CMD, then follow the steps below to fix the issue.

How to resolve the issue?

1. If type=USER_CMD is present, then go to Settings > Event types.

2. Search for auditd_authentication.

3. Click auditd_authentication (the default values should match with the following image).

1. Update the search string with the following contents, then click Save.

Warning -> ‘list’ command: Limit of ‘100’ for values reached

If you see below warning: 'list' command: Limit of '100' for values reached. Additional values may have been truncated or ignored.

From any of the below alerts, then kindly ignore it, as that is expected behavior. * Ransomware - Spike in File Writes * Ransomware - Common Ransomware File Extensions * Network Compromise - DDoS Behavior Detected

Getting “The lookup table ‘cs_windows_cert_name_mapping.csv’ requires a .csv or KV store lookup definition.” error on dashboards

• This error needs to occur in Cyences app since the cs_windows_cert_name_mapping.csv lookup is used in the query instead of props.conf.

• Add the CSV file with Certificate_Template and Certificate_Name mapping details at location $SPLUNK_HOME/etc/apps/cyences_app_for_splunk/lookups/cs_windows_cert_name_mapping.csv

• An example of file content:

  Certificate_Template,Certificate_Name
  x.x.x.xx.....,my_cert