Falco by sysdig

Earlier this week the guys over at sysdig↗ announced the availability of Falco, a behavioral security service which is built on top of their core Open Source sysdig engine. As is always the case when I try new things, I launched a Digital Ocean↗ Droplet running CentOS 7.2. Once the Droplet was available I ran the command to get the basics configured on the droplet;

curl -fsS https://raw.githubusercontent.com/russmckendrick/DOBootstrap/master/do-bootstrap.sh | bash

Once the Droplet was configured I installed Falco using the repo provided by sysdig by running the following commands;

rpm — import https://s3.amazonaws.com/download.draios.com/DRAIOS-GPG-KEY.public
curl -s -o /etc/yum.repos.d/draios.repo http://download.draios.com/stable/rpm/draios.repo
yum -y install kernel-devel-$(uname -r)
yum -y install falco

With Falco installed, I started it up with the following command;

service falco start

and checked that everything was running as expected;

[root@server ~]# service falco status
falco.service — LSB: Falco syscall monitoring agent
Loaded: loaded (/etc/rc.d/init.d/falco)
Active: active (running) since Sun 2016–05–22 12:27:29 BST; 22s ago
Docs: man:systemd-sysv-generator(8)
Process: 22019 ExecStart=/etc/rc.d/init.d/falco start (code=exited, status=0/SUCCESS)
CGroup: /system.slice/falco.service
└─22024 /usr/bin/falco — daemon — pidfile=/var/run/falco.pid

May 22 12:27:28 server.mckendrick.io systemd[1]: Starting LSB: Falco syscall monitoring agent…
May 22 12:27:29 server.mckendrick.io falco[22021]: Falco initialized with configuration file /etc/falco.yaml
May 22 12:27:29 server.mckendrick.io falco[22019]: Starting falco: Sun May 22 12:27:29 2016: Falco initialized with configuration file /etc/falco.yaml
May 22 12:27:29 server.mckendrick.io falco[22021]: Parsed rules from file /etc/falco_rules.yaml
May 22 12:27:29 server.mckendrick.io falco[22019]: Sun May 22 12:27:29 2016: Parsed rules from file /etc/falco_rules.yaml
May 22 12:27:29 server.mckendrick.io falco[22019]: [ OK ]
May 22 12:27:29 server.mckendrick.io systemd[1]: Started LSB: Falco syscall monitoring agent.
May 22 12:27:48 server.mckendrick.io systemd[1]: Started LSB: Falco syscall monitoring agent.
[root@server ~]#

As you can, it was really straight forward to install. Next up I wanted to trigger a rule, looking through the default ruleset↗ I noticed the following;

- macro: adduser_binaries
condition: proc.name in (adduser, deluser, addgroup, delgroup)
- rule: user_mgmt_binaries
desc: activity by any programs that can manage users, passwords, or permissions. sudo and su are excluded. Activity in containers is also excluded — some containers create custom users on top of a base linux distribution at startup.
condition: spawn_process and not proc.name in (su, sudo) and not container and (adduser_binaries or login_binaries or passwd_binaries or shadowutils_binaries)
output: “User management binary command run outside of container (user=%user.name command=%proc.cmdline)”
priority: WARNING

So I added a user, as you can see it triggered the rule;

[root@server ~]# adduser wibble
[root@server ~]# tail -2 messages
May 22 08:06:58 digitalocean falco: User management binary command run outside of container (user=root command=adduser wibble)
May 22 08:06:58 digitalocean falco: Sensitive file opened for reading by non-trusted program (user=root command=adduser wibble file=/etc/shadow)

After this really quick installation and five minutes of messing about with the rules I can already think of several use cases for Falco and will be keeping a close eye on it.

You can find the GitHub repo for Falco at https://github.com/draios/falco↗ and also the announcement post here↗.

Falco by sysdig

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