Greenbone Vulnerability Management

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Greenbone Vulnerability Management (GVM) is a network security scanner with associated tools like a graphical user front-end. The core component is a server with a set of network vulnerability tests (NVTs) to detect security problems in remote systems and applications. It is used by both offensive and defensive security experts to determine attack surfaces.

GVM was previously known as Open Vulnerability Assessment System (OpenVAS). OpenVAS was a fork of Nessus, the popular corporate security scanner maintained by Tenable. Both OpenVAS and Nessus were originally built from the nmap port scanner.

This guide provides instructions on installing a complete server solution for vulnerability scanning and vulnerability management.

Installation

net-analyzer/gvm is the resolver package of core GVM components and has several USE flags that may be desired for certain bigger setups. As this article aims at installing and configuring a basic GVM setup.

USE flags

USE flags for net-analyzer/gvm Greenbone Vulnerability Management, previously named OpenVAS

cli Command Line Interface for OpenVAS Scanner
doc Add extra documentation (API, Javadoc, etc). It is recommended to enable per package instead of globally
gsa Greenbone Security Assistant (WebUI)
ldap Add LDAP support (Lightweight Directory Access Protocol)
ospd Enable support for scanner wrappers
radius Add support for RADIUS authentication
snmp Add support for the Simple Network Management Protocol if available

Emerge

The net-analyzer/gvm is a meta-package in essence. You should install the last available version (22.4 at time of writing). It depends upon the command-line interface, libraries, manager, scanner, and tools. Do not be surprised if the dependency list is a little long:

root #emerge --ask net-analyzer/gvm

net-analyzer/gvm emerges the following packages: net-analyzer/gvm-libs, net-analyzer/gvmd, net-analyzer/openvas-scanner, net-analyzer/greenbone-feed-sync, dev-db/pg-gvm, dev-libs/paho-mqtt-c.

To perform a complete installation add these use flags to net-analyzer/gvm : +cli, +gsa, +ospd. This will install: net-analyzer/gvm-tools, net-analyzer/gsad (that will require net-analyzer/gsa), net-analyzer/ospd-openvas (that will require net-analyzer/notus-scanner).

Additional software

Additional support for extra scanning checks can be gained from emerging the following software:

Package Description
net-analyzer/nmap For nmap — to add port scanning and service detection based on nmap
net-analyzer/ike-scan For ike-scan — an IPsec VPN scanning, fingerprinting and testing tool.
net-analyzer/nikto For Nikto — a web server scanning and testing tool.

Configuration

Redis

Openvas-scanner relies on Redis, which is an in-memory data structure storage system. Redis should be configured to listen to a socket.

Starting with openvas-scanner-22.7.2 a separate redis instance is configured for GVM by gentoo portage. The configuration file is /etc/gvm/redis-openvas.conf

If you need, you can edit /etc/gvm/redis-openvas.conf or stay with default settings.

FILE /etc/gvm/redis-openvas.conf
unixsocket /run/redis-openvas/redis.sock 
unixsocketperm 770 
port 0

Note that this configuration will only allow the 'redis' user and users in 'redis' group to access the socket. We will later fix that by setting a filesystem ACL on the socket, allowing the 'gvm' user, i.e., the user OpenVAS runs under, to access it.

Then enable and start the redis service:

OpenRC

root #rc-update add redis-openvas
root #rc-service redis-openvas start

systemd

Note that the systemd service of Redis may require setting RuntimeDirectory=redis so that /run/redis, under which the socket configured, is created.

root #systemctl enable --now redis-openvas.service

Starting from gvm-22.4 a gvm.target is created to start all gvm related services. We will illustrate this later.

PostgreSQL backend

Keep in mind that GVM is run under user and group 'gvm'. So create a database-user named 'gvm' and database named 'gvmd'.

To run psql, PostgreSQL has to be running. Refer to the PostgreSQL/QuickStart and to the section PostgreSQL/QuickStart#Starting the server

root #sudo -u postgres psql
CODE PostgreSQL setup
create database gvmd;
create role dba with superuser noinherit;
create user gvm;
grant all privileges on database gvmd to gvm;
grant dba to gvm;

Note the last command, where we grant the 'gvm' user the 'dba' role, which is essentially 'superuser', the highest privileged role of postgres. This means that the 'gvm' user has access to all database in postgres. You may do not want to use the postgres database with other applications besides GVM due to this. The 'dba' role is required, as it is used, and hence expected by gvmd to install GVM-specific postgres plugins.

Workaround for PostgreSQL version 15 (released October, 2022), give the gvm user permission to modify the public schema:

CODE If using PostgreSQL 15 or higher
grant ALL on SCHEMA public TO gvm;

gvm-22.4 requires a pgsql extension to be installed in the gvmd database. This extension contains functionality for ical object manipulation and it is provided by net-analyzer/pg-gvm.

To use the extension in a database create the extension using: CREATE EXTENSION "pg-gvm";

root #sudo -u postgres psql gvmd
CODE CREATE EXTENSION "pg-gvm"
gvmd=>	CREATE EXTENSION "pg-gvm";
gvmd=>	\q

Sync the Greenbone Community Feed

Upgrade the Greenbone Community Feed data:

Note
Verify RSYNC (TCP/873) has been enabled without NAT and Proxy to greenbone IPv6/IPv4 feed server [feed.community.greenbone.net]. SSH port 24 or 443 is only supported through the GSF (Paying Greenbone Customer) service level. Troubleshoot by checking the firewall for active connections. Due note systems sharing an external IP address many encounter issues, since one feed-sync per IP is the limit for the GCF. This can be verified by telneting to the Port 873 to test communication.
user $sudo -u gvm greenbone-feed-sync

To download only a specific feed content the --type argument can be used

user $sudo -u gvm greenbone-feed-sync --type nvt

Possible values for the --type argument are: all, nvt/nvts, gvmd-data, scap, cert, notus, nasl, report-format/report-formats, scan-config/scan-configs or port-list/port-lists. Default value: all

Warning
The greenbone-feed-sync must be executed as the gvm user.

gvmd certificate generation

Now, generate the certificate for gvmd.

The certificate infrastructure enables GVM daemons to communicate in a secure manner and is used for authentication and authorization before establishing TLS connections between the daemons.

Setup the certificate automatically by running:

user $sudo -u gvm gvm-manage-certs -a

Starting Greenbone daemons

After redis configuration and GVM feed rsync tasks are completed, the daemons will need to be started in the following order.

  • notus-scanner -> ospd-openvas > gvmd > gsad
  • ospd-openvas will start redis-openvas and mosquitto.


If your system uses sys-apps/systemd, you can use the gvm.target to start all services at once:

root #systemctl start gvm.target

Notus Scanner

OpenRC

root #rc-service notus-scanner start
root #rc-update add notus-scanner

systemd

root #systemctl enable --now ospd-openvas.service

For validating the feed content, a GnuPG keychain with the Greenbone Community Feed integrity key needs to be created.

user $curl -f -L https://www.greenbone.net/GBCommunitySigningKey.asc -o /tmp/GBCommunitySigningKey.asc
user $export GNUPGHOME=/tmp/openvas-gnupg
user $mkdir -p $GNUPGHOME
user $gpg --import /tmp/GBCommunitySigningKey.asc
user $echo "8AE4BE429B60A59B311C2E739823FAA60ED1E580:6:" | gpg --import-ownertrust
user $export OPENVAS_GNUPG_HOME=/etc/openvas/gnupg
user $sudo mkdir -p $OPENVAS_GNUPG_HOME
user $sudo cp -r /tmp/openvas-gnupg/* $OPENVAS_GNUPG_HOME/
user $sudo chown -R gvm:gvm $OPENVAS_GNUPG_HOME

To enable feed validation, you can edit /etc/gvm/notus-scanner.toml and set the variable disable-hashsum-verification = false

FILE /etc/gvm/notus-scanner.tomlnotus-scanner.toml
[notus-scanner]
mqtt-broker-address = "localhost"
mqtt-broker-port = "1883"
products-directory = "/var/lib/notus/products"
pid-file = "/run/notus-scanner/notus-scanner.pid"
log-file = "/var/log/gvm/notus-scanner.log"
log-level = "INFO"
disable-hashsum-verification = false

OpenVAS Scanner

With ospd-openvas-22.5.1.ebuild a custom override for the service is provided in /etc/systemd/system/ospd-openvas.service.d/00gentoo.conf

You can edit this file if you need to customize ospd-openvas service.

The service uses /etc/gvm/ospd-openvas.conf as ospd-openvas conf file.

Start OSDP OpenVAS scanner daemon:

OpenRC

root #rc-service ospd-openvas start
root #rc-update add ospd-openvas

systemd

root #systemctl enable --now ospd-openvas.service

This will take a while, since OpenVAS here is loading all NVT definition downloaded. Check the status of openvas that completed loading NVTs before starting gvmd:

root #ps aux | grep openvas
/usr/sbin/redis-server unixsocket:/run/redis-openvas/redis.sock
/usr/bin/python3.11 /usr/lib/python-exec/python3.11/ospd-openvas --config /etc/gvm/ospd-openvas.conf --log-config /etc/gvm/ospd-logging.conf --lock-file-dir /var/lib/openvas --socket-mode 0o770 --mqtt-broker-address localhost --mqtt-broker-port 1883 --notus-feed-dir /var/lib/notus/advisories
openvas: openvas: Reloaded 70200 of 86149 NVTs (81% / ETA: 00:08)
...

Greenbone Vulnerability Manager (gvmd)

Start Greenbone Vulnerability Manager daemon:

OpenRC

root #rc-service gvmd start
root #rc-update add gvmd

systemd

root #systemctl enable --now gvmd.service

This will take a while, since 'gvmd' here is rebuilding his database with all NVT definition downloaded. You will see with ```ps aux``` the gvmd process in "Syncing SCAP" state. Don't worry, after a while gvmd will load scapdata. This is normal to take long time.

Create a new user with Admin role, and take note of the generated password under user gvm:

root #sudo -u gvm bash
user $gvmd --create-user=admin --role=Admin
User created with password '18664575-7101-4ceb-8a94-429a376824e6
Tip
To change the password, substitute MyNewVeryStrongPassword with a new password:
user $gvmd --user=admin --new-password=MyNewVeryStrongPassword

Set the Feed Import Owner

Now obtain the UUID of the created admin user via

user $gvmd --get-users --verbose

and set it as feed owner

user $gvmd --modify-setting 78eceaec-3385-11ea-b237-28d24461215b --value <uuid_of_user>

Greenbone Vulnerability Assistant WebUI (gsad)

Greenbone Security Assistant (GSA) WebUI listens port 9392 default on localhost. If you wish you can configure Greenbone Security Assistant (GSAD) to listen to other interfaces rather than localhost only, so it is reachable from other hosts.

FILE /etc/conf.d/gsadOpenRC
GSAD_LISTEN_ADDRESS="--listen=0.0.0.0"
FILE /etc/gvm/sysconfig/gsad-daemon.confsystemd
GSAD_LISTEN_ADDRESS="--listen=0.0.0.0"

Or, in one shot:

CODE OpenRC
sed -i -e "s/127\.0\.0\.1/0\.0\.0\.0/g" /etc/conf.d/gsad
CODE systemd
sed -i -e "s/127\.0\.0\.1/0\.0\.0\.0/g" /etc/gvm/sysconfig/gsad-daemon.conf
Tip
If you prefer reverse proxying with NGINX check out the following file: /etc/openvas/gsa.nginx.reverse.proxy.example.

Start greenbone vulnerability assistant daemon:

OpenRC

root #rc-service gsad start
root #rc-update add gsad

systemd

root #systemctl enable --now gsad.service

Open the browser at the IP address or domain name where GSAD is running, on port 9392, and login with the credentials previously created.

Happy vulnerability assessment!

Misc

Updating gvmd version

Migrating the database

When updating to a previous gvmd version you need to migrate the database to the new version or gvmd would not start.

if this is the case you can migrate the database issuing the following commands:

root #mkdir /run/gvmd
root #setfacl -m u:gvm:rwx /run/gvmd/
root #sudo -u gvm gvmd --migrate

Configure trusted NVTs

Note
This section is left here to avoid broken links. The same information are reported under Notus_Scanner section

Sum-up: https://community.greenbone.net/t/gcf-managing-the-digital-signatures/101 :

Trusted NVTs

"Signed NVTs are usually provided by NVT Feed Services. For example, the NVTs contained in the OpenVAS NVT Feed are signed by the "OpenVAS Transfer Integrity" key which you can find at the bottom of this page. If you have already installed OpenVAS, you can use the "greenbone-nvt-sync" command to synchronize your NVT collection with the OpenVAS NVT Feed and receive signatures for all NVTs."

For updated instrucions, refer to: https://greenbone.github.io/docs/latest/22.4/source-build/index.html#feed-validation

Create key

You need to choose Realname, Email and a Password. Example:

root #gpg --homedir=/etc/openvas/gnupg --gen-key
Realname: openvas 
Email: openvas@localhost
Password: admin

Add a certificate to OpenVAS Scanner keyring

Add the OpenVAS scanner Integrity Key:

root #wget https://www.greenbone.net/GBCommunitySigningKey.asc
root #gpg --homedir=/etc/openvas/gnupg --import GBCommunitySigningKey.asc

Set trust

To mark a certificate as trusted for your purpose, you have to sign it. The preferred way is to use local signatures that remain only in the keyring of your OpenVAS Scanner installation.

To finally sign a certificate you need to know its KEY_ID. You either get it from the table at the bottom or via a "list-keys" command.

Then you can locally sign:

root #gpg --homedir=/etc/openvas/gnupg --list-keys
root #gpg --homedir=/etc/openvas/gnupg --lsign-key KEY_ID

For example, to express your trust in the OpenVAS Transfer Integrity you imported above, you could use the following command:

root #gpg --homedir=/etc/openvas/gnupg --lsign-key 0ED1E580

Before signing you should be absolutely sure that you are signing the correct certificate. You may use its fingerprint and other methods to convince yourself.

To enable NVT signing on openvassd:

CODE enable NVT signing
sed -i -e "s/disable-hashsum-verification*/disable-hashsum-verification = false/g" /etc/gvm/notus-scanner.toml

As last step, restart openvas service:

root #rc-service ospd-openvas restart

Troubleshooting

If you encounter a problem on fresh installation , first stop greenbone daemons (notus-scanner, ospd-openvas, gvmd and gsad) and clear redis cache:

root #redis-cli -s /var/run/redis-openvas/redis.sock FLUSHDB
root #redis-cli -s /var/run/redis-openvas/redis.sock FLUSHALL

Clean pre-generated NVTs and database;

root #rm -rf /var/lib/gvm/*

Then follow the instructions again.

See Also

  • Building 22.4 from Source - A comprehensive guide to build and configure GVM from sources.
  • PostgreSQL — a free and open source relational database management system (RDBMS).
  • Nmap — an open source recon tool used to check for open ports, what is running on those ports, and metadata about the daemons servicing those ports.
  • Security Handbook — valuable guidance on Gentoo Linux security and cybersecurity in general.