8. Troubleshooting

8.1. Diagnostic Pack

The diagnostic package is an archive generated on ASGARD server to help Nextron support engineers with the debugging of your problem. It contains the system configuration and log data of an ASGARD instance.

You can generate a Diagnostic Package in Systems Status > Tab: Logs > Diagnostics Package.

Diagnostics Pack
Diagnostics Pack Download View

The package can have a size that cannot be shared via Email. In this case you can either

  1. ask us for an upload link (secure file sharing) or
  2. remove big log files from the package (e.g. the file ./var/lib/nextron/asgard2/log/agent-access.log is often responsible for 97% of the package size)

8.2. Agent Debugging

8.2.1. Internal Agent Debugging

Edit the file asgard2-agent.yaml and set the value of write_log to true. The file can be found in C:\Windows\System32\asgard2-agent\ or /var/lib/asgard2-agent/ for Windows and Linux/macOS, respectively.

write_log: true

After making these changes, restart the ASGARD service. You can then find log entries and possible error messages in the file asgard2-agent.log in the same directory as the configuration file.

Note: The value is set to false by default, because the agent doesn't rotate or compress these logs. Leaving that value on true could cause that file to grow very big and use a significant amount of disk space. We recommend resetting it after the debugging session.

8.2.2. Go Debug Logging

On Windows, open the cmd.exe as Administrator. Set some environment variables.

C:\Windows\system32>set GRPC_GO_LOG_SEVERITY_LEVEL=info
C:\Windows\system32>set GODEBUG=http2debug=2

Navigate into the agent's program directory and start it to see all output messages.

C:\Windows\system32>sc stop asgard2-agent
C:\Windows\system32>cd C:\Windows\system32\asgard2-agent\
C:\Windows\system32\asgard2-agent>asgard2-agent.exe

Interrupt the agent with CTRL+C. Don't forget to start the Windows service after the debugging session.

C:\Windows\system32\asgard2-agent>sc start asgard2-agent

On Linux, open a shell as root (sudo).

nextron@asgard:~$ sudo su -
[sudo] password for nextron:
root@asgard:~#
root@asgard:~# export GRPC_GO_LOG_SEVERITY_LEVEL=info
root@asgard:~# export GODEBUG=http2debug=2

Navigate into the agent's program directory and start it to see all output messages.

root@asgard:~# systemctl stop asgard2-agent
root@asgard:~# cd /var/lib/asgard2-agent/
root@asgard:/var/lib/asgard2-agent# ./asgard2-agent

Interrupt the agent with CTRL+C. Don't forget to start the Linux service after the debugging session.

root@asgard:/var/lib/asgard2-agent# systemctl start asgard2-agent

8.2.3. Aurora Diagnostics Pack

If Aurora does not behave like it should, e.g. using more resources than you expected, you can create a diagnostics pack for our support to help in troubleshooting the issue. This can be conveniently done using the playbook [Default] Create and Collect Aurora Agent Diagnostics Pack (Windows).

It can be run from Asset Management > Response Action (Play button) or from Response Control > Tasks > Add Task or if needed as a group task. The resulting diagnostics.zip can be downloaded from the third step in the Playbook Result tab of the expanded task.

8.2.4. Duplicate Assets Remediation

If you are seeing the Duplicate Assets view in your Asset Management, you need to fix the issue to avoid unwanted behavior of this asset. To fix the issue, you need to uninstall the current ASGARD agent, delete the configuration files, and redeploy a fresh copy.

Troubleshooting Duplicate Assets

Troubleshooting Duplicate Assets

  • To uninstall the ASGARD agent, please follow the instructions in Uninstall ASGARD Agents.
  • To delete the configuration files, make sure that the following folder is deleted before installing a new agent:
    • Windows: C:\Windows\System32\asgard2-agent\
    • Linux: /var/lib/asgard2-agent/
  • To install the ASGARD agent, please follow the instructions in ASGARD Agent Deployment.

It is also recommended to redeploy the ASGARD Service Controller.

  • To uninstall the ASGARD Service Controller, please follow the instructions in Uninstall ASGARD Service Controller.
  • To install the ASGARD Service Controller, please follow the instructions in Service Controller Installation. You need to wait a few minutes until the asset is connected to your ASGARD before you continue with this step. Please note that you might need to accept the Asset Request.

8.3. SSL Interception

Using a web proxy with TLS/SSL interception will break the installation routine and shows this error:

Certificate verification failed: The certificate is NOT trusted. The certificate issuer is unknown.  Could not handshake: Error in the certificate verification.

Solution: Disable TLS/SSL interception for our update servers.

  • update3.nextron-systems.com

Used for THOR updates:

  • update1.nextron-systems.com
  • update2.nextron-systems.com

We do not support setups in which the CA of the intercepting proxy is used on our ASGARD appliances.

8.4. Using Hostname instead of FQDN

The most common error is to define a simple hostname instead of a valid FQDN during installation. This happens if no domain name has been set during the setup step Network Configuration (Domain name).

This leads to a variety of different problems.

The most important problem is that ASGARD Agents that install on endpoints will never be able to resolve and connect to the ASGARD server.

8.4.1. Errors that appear in these cases

Apr 23 12:07:12 debian10-dev/10.10.30.118 ASGARD_AGENT: Error:
could not run: rpc error: code = Unavailable desc = connection
error: desc = "transport: authentication handshake failed: x509:
certificate is valid for wrong-fqdn, not asgard.nextron.internal"

8.4.2. How to Fix a non-existing or wrong FQDN

The FQDN is set at installation time and is composed by the hostname and the domain name. The ASGARD Agents require a resolvable FQDN to correctly operate and connect to the ASGARD Server. One of the processes which are executed at installation time include the integration of the FQDN - which should be set during installation - into the ASGARD agents. If we incorrectly set the FQDN or leave any of those values empty, the agents will fail to connect to ASGARD.

With this fix we will set a new FQDN for the ASGARD Management Center, recreate the internal certificates, and rebuild the agents.

Warning

The used FQDN in this manual is just an example. Please use the FQDN of your domain. make sure the FQDN is resolvable via your DNS server.

8.4.2.1. Set a valid FQDN

To set a valid FQDN for your ASGARD Management Center server, follow the steps below. We are assuming that your local DNS server already has an A-Record assigned, so your clients can resolve the new hostname/FQDN of your ASGARD Management Center.

Connect via SSH to the ASGARD Management Center:

user@somehost:~$ ssh nextron@asgard-mc.example.org

Edit the hosts file. Please be careful with the changes in this file, as this might make your system unusable!

nextron@asgard-mc:~$ sudoedit /etc/hosts
[sudo] password for nextron:

You need to change the following line (do not change the IP-Address!):

1
2
3
4
5
6
7
127.0.0.1       localhost
172.16.0.20     asgard-mc

# The following lines are desirable for IPv6 capable hosts
::1     localhost ip6-localhost ip6-loopback
ff02::1 ip6-allnodes
ff02::2 ip6-allrouters

To this (values are examples, please change accordingly!)

1
2
3
4
5
6
7
127.0.0.1       localhost
172.16.0.20     asgard-mc.example.org asgard-mc

# The following lines are desirable for IPv6 capable hosts
::1     localhost ip6-localhost ip6-loopback
ff02::1 ip6-allnodes
ff02::2 ip6-allrouters

Note

If you did not set a static IP-Address for your ASGARD Management Center server, your IP-Address in the second line of the file might be 127.0.1.1. This is due to your server using DHCP. It is advised that you are using a static IP-Address. To change this, please see Changing the IP-Address.

You can verify if the changes worked. Run the following commands and see the difference in the output:

nextron@asgard-mc:~$ hostname --fqdn
asgard-mc.example.org
nextron@asgard-mc:~$ hostname
asgard-mc

If the first command shows the FQDN and the second one the hostname without domain, your changes were set up correctly and you can continue to the next step.

8.4.2.2. Recreate the TLS Certificate

We need to recreate the TLS certificate to make the Agent to ASGARD communication possible again. Create a new file which will contain the script with the fix. In this example we'll use nano as the text editor. Make sure that the system has a valid FQDN.

nextron@asgard-mc:~$ nano fix-fqdn.sh

Insert the following content into the text editor:

1
2
3
4
5
6
7
8
#!/bin/bash
export FQDN=$(hostname --fqdn)

sed "s/\$FQDN/${FQDN}/" /etc/nextron/asgard2/server_cert_ext.cnf.in > /etc/nextron/asgard2/server_cert_ext.cnf
openssl req -new -nodes -subj "/O=Nextron Systems GmbH/CN=${FQDN}" -key /etc/nextron/asgard2/client-service.key -out /etc/nextron/asgard2/client-service.csr
openssl x509 -req -in /etc/nextron/asgard2/client-service.csr -CA /etc/nextron/asgard2/ca.pem -CAkey /etc/nextron/asgard2/ca.key -CAcreateserial -days 36500 -out /etc/nextron/asgard2/client-service.pem -extfile /etc/nextron/asgard2/server_cert_ext.cnf
systemctl restart asgard2
asgard2-repacker -host $FQDN

After changing the variables to the desired values, save the file. In nano this can be done in by pressing CTRL + X and confirming the changes with y.

Give the created script execution permissions and execute it:

nextron@asgard-mc:~$ chmod +x fix-fqdn.sh
nextron@asgard-mc:~$ sudo ./fix-fqdn.sh

You should now be able to reach the ASGARD Server via the new FQDN. Navigate to https://<YOUR-FQDN>:8443, which reflects the FQDN we set earlier.

At this point you have to install the ASGARD agents on your endpoints again. Remember to review the network requirements section to ensure all needed ports are open to the ASGARD Management Center from your endpoints. See Network Requirements

8.5. ASGARD Errors

8.5.1. ASGARD noticed that the THOR scan failed

In some cases THOR fails to complete its scan and ASGARD reports the following error.

ASGARD noticed that the THOR scan failed

could not remove temp directory: remove C:\Windows\Temp\asgard2-agent\12fa35a6762a\thor\signatures\sigma\windows\file_event_win_webshell_creation_detect.yms:
The process cannot access the file because it is being used by another process. exit status 1
(scan result does not exist)

The most likely reason for this error is an Antivirus interaction. The Antivirus killed the THOR process and still holds a handle to one of the signature files. The "THOR Launcher" can only report that the process was terminated and that it isn't able to remove all files because the Antivirus process still has that open handle on the file.

Solution:

Configure an Antivirus exclusion for THOR. See Antivirus or EDR Exclusions for more details.

8.6. Resetting TLS/SSL Certificates

8.6.1. Web GUI: Regenerate the Self-Signed Certificate

ASGARD ships with a self-signed certificate for its web interface that expires after 182 days. If you do not use your own CA infrastructure and want to renew the certificate or want to revert from a broken state, you can recreate a self-signed certificate. To do so log in using SSH and execute:

nextron@asgard:~$ sudo openssl req -new -newkey rsa:4096 -days 182 -nodes -x509 -subj "/O=Nextron Systems GmbH/CN=$(hostname --fqdn)" -keyout /etc/nextron/asgard2/server.key -out /etc/nextron/asgard2/server.pem

You need to restart ASGARD in order for the changes to take effect.

nextron@asgard:~$ sudo systemctl restart asgard2.service

8.6.2. Regenerate ASGARD Server Certificate Agent Communication

In order to reset the certificate that ASGARD uses to communicate with the agents, use the following commands. The agent should immediately trust the new certificate, as it was generated using the CA they already trust.

nextron@asgard:~$ su asgard2 -s /bin/sh <<'EOF'
openssl req -new -nodes -subj "/O=Nextron Systems GmbH/CN=ASGARD Management Center" -key /etc/nextron/asgard2/client-service.key -out /etc/nextron/asgard2/client-service.csr
openssl x509 -req -in /etc/nextron/asgard2/client-service.csr -CA /etc/nextron/asgard2/ca.pem -CAkey /etc/nextron/asgard2/ca.key -CAcreateserial -days 36500 -out /etc/nextron/asgard2/client-service.pem -extfile /etc/nextron/asgard2/server_cert_ext.cnf
EOF

8.7. Admin User Password Reset

If you've lost the password of the local admin user (Web GUI) but still have access the system via SSH, you can reset it via command line using the following command.

nextron@asgard:~$ sudo mysql asgard -e "UPDATE users SET password = 'YmIc6P_6jdbeEL0HY4xIcpYstmM' WHERE name = 'admin';"

This resets the password to admin. You should then change that password immediately.

8.8. Reset Two Factor Authentication for a specific User

If you or another user lost their second factor (2FA) to log into the ASGARD Web UI, you have to reset the users MFA Settings. If you cannot access the Web UI, use the Command Line method.

There are two possible ways to reset Two Factor Authentication for a specific user. We recommend to use the first option via the WebUI.

8.8.1. Using the Web UI

Log into ASGARDs Web UI as a user with administrative privileges.

Navigate to Settings > Authentication > Users and edit the user you want to reset 2FA for. On the bottom of the popup you will see that the 2FA option is enabled. Disable the option and click Edit User (Leave everything else as it is; do not fill in a new password if not necessary).

Disable 2FA via WebUI

After you edited the user, the Two Factor Authentication will be disabled and the user can log into ASGARD without 2FA.

8.8.2. Using the Command Line Interface

Note

This method needs SSH access to ASGARD.

Log into your ASGARD via SSH. You can reset the users MFA Settings with the following command (in this example we assume that the user is called john):

nextron@asgard:~$ sudo mysql asgard --execute "UPDATE users SET tfa_valid = 0 WHERE name = 'john';"

Warning

This will disable the 2FA settings directly in the database. Please make sure the command and especially the username is correct.

If you don't know the exact username for a user, you can use the following command to get all the usernames and the 2FA status from ASGARD (if tfa_valid has a value of 1, this means the user has Two Factor Authentication enabled).

nextron@asgard:~$ sudo mysql asgard --execute "select name,tfa_valid from users;"
+----------+-----------+
| name     | tfa_valid |
+----------+-----------+
| admin    |         1 |
| john     |         0 |
| rickroll |         1 |
+----------+-----------+

This command will also allow you to verify if the UPDATE command was successful (tfa_valid should be 0).

8.9. Scheduled Scans do not run at the correct time

In some cases the timezone during the installation of the server image might not be correct. To see if you have this problem in your current installation, please log into your server and execute the following command:

nextron@asgard:~$ timedatectl
               Local time: Mon 2022-10-24 09:52:03 BST
           Universal time: Mon 2022-10-24 08:52:03 UTC
                 RTC time: Mon 2022-10-24 08:52:04
                Time zone: Europe/London (BST, +0100)
System clock synchronized: no
              NTP service: inactive
          RTC in local TZ: no

If you see that the Time zone is incorrect, follow the next steps to correct it.

List all the timezones with timedatectl list-timezones. If you want to search for a specific Country/City, you can use grep, e.g. timedatectl list-timezones | grep Prague.

Now that you have the correct timezone you can set it the following way:

nextron@asgard:~$ sudo timedatectl set-timezone Europe/Prague
nextron@asgard:~$ timedatectl
               Local time: Mon 2022-10-24 10:56:45 CEST
           Universal time: Mon 2022-10-24 08:56:45 UTC
                 RTC time: Mon 2022-10-24 08:56:46
                Time zone: Europe/Prague (CEST, +0200)
System clock synchronized: no
              NTP service: inactive
          RTC in local TZ: no

Please reboot the system after the changes have been made.

Warning

This might cause problems with existing Scheduled Scans!

8.10. Aurora is generating too many False Positives

In some environments, Aurora might generate a high amount of False Positives. This should never be the case, since Aurora should only alert on very few and mostly important findings. Most likely a rule is matching on the environment and generates too many false positives. To circumvent this, you can disable the rule and set a filter later on. For Tuning, please see False Positive Tuning of Sigma Rules.