Last week Andrew Storms put up a good post hinting at the promise of security automation in [SecDevOps: Security Automation By Example – The Firewall Change]. He included an example of automating a series of actions when a firewall rule is changed. It’s a good article, although I’m increasingly convinced there’s no such thing as SecDevOps. In my book, it’s all DevOps, but that’s fodder for another post (when I’m not battling a stomach bug). However, what Andrew describes is more of what I consider an automated assist. It isn’t necessarily full automation, since it triggers on a manual firewall rule change. Ideally we rarely manually change a firewall (or Security Group) rule, and rely more on self-configuring based on policies. Yeah, I know, the usual analyst BS, so here’s a bit of process, and a bit of code. Let’s approach this differently. Take Andrew’s process, but let’s have the security group or host firewall self configure based on the asset. My example is going to be Amazon Web Services specific, since I have some code snippets to show off how it works. (Sorry, I don’t have the time or intestinal fortitude to write out all the code today; seriously, where did this bug come from?!?) There are two techniques I generally see forming the core of dynamic Security Group policy enforcement:
- Tags
- Configuration Management integration
Some cloud services, like AWS, support tags at the object (in this case, instance) level. These tags can tie internally to policies while also being consumable for external tools. Here is a policy I use that restricts access to an object if the “SecurityStatus” tag is “IR” (for “Incident Response”):
{
"Version": "2012-10-17",
"Statement": [
{
"Action": "*",
"Condition": {
"StringEquals": {
"ec2:ResourceTag/SecurityStatus": "IR"
}
},
"Resource": [
"*"
],
"Effect": "Deny"
}
]
}
I could apply that tag manually or automatically, and in either case the instance can no longer be managed by any account this policy is applied to. Now this doesn’t help us change firewall/Security Group rules, since you can’t manage those directly in EC2 based on tags (but I had the policy handy to demo, so there you go). For that to work, you need to write your own code to scan for tags and then take actions. I don’t have exactly the right code examples on hand. but here are some snippets to get you close. Most of these are cribbed from my SecuritySquirrel proof of concept on GitHub. They are all in Ruby, using the AWS 2.0 developer preview SDK. First, to pull a list of all instances with a certain tag, you can use the following:
def testing
# testing some tag code
instancelist = @@ec22.describe_tags(
filters: [
{
name: "key",
values: ["SecurityStatus"]
}
]
)
puts instancelist.to_h
end
That shows everything with the SecurityStatus tag (instances and values, shown as a hash), but you could also filter on value. From there, you could pull the instance IDs with a map (you might want to further filter only on instances, but if you made it this far you can figure that out):
instances = instancelist.map(&:resource_id)
Then you can pump those into a method to change the Security Group. Here’s the one from SecuritySquirrel that places an instance into a “Quarantine” group:
def quarantine
#this method moves the provided instance into the Quarantine security group defined in the config file.
puts ""
puts "Quarantining #{@instance_id}..."
quarantine = @@ec22.modify_instance_attribute(instance_id: "#{@instance_id}", groups: ["#{@QuarantineGroup}"])
puts "#{@instance_id} moved to the Quarantine security group from your configuration settings."
end
Want to trigger some scanning? Here’s a code snippet to trigger a Qualys scan on an instance from a virtual appliance in your AWS account (keep in mind, I’m skipping a bunch of important pieces, like configuring the service and authenticating):
instance_IP = instance_details.reservations.first.instances.first.private_ip_address
timestamp = Time.new
scan =(HTTParty.post("https://qualysapi.qg2.apps.qualys.com/api/2.0/fo/scan/",
:basic_auth => @qualysauth,
:query => {
:action => "launch",
:scan_title => "SecuritySquirrel Scan at #{timestamp}",
:ip => "#{instance_IP}",
:option_title => "Initial Options",
:iscanner_name => "us-west-2"
},
:headers => { "X-Requested-With" => "ruby httparty"}))
puts "Launching Qualys scan named: SecuritySquirrel Scan at #{timestamp}"
Or want to change the CloudPassage Halo host firewall rules? Well, that code uses a pre-release of their Ruby SDK, so I’ll save it for another day (I’m not employed by them, but they let me play with the pre-release gem). These examples are all based on tags, but remember that if you use a tool like Chef or Puppet you can do the exact same thing based on what software is configured and running within the instance. For example, you could create a policy to quarantine all SSL when the Heartbleed vulnerability hit by closing off port 443 on any server running the vulnerable OpenSSL package, then remove the rule when it is updated to the patched version. I’m a bit rusty since I don’t code every day, but I could probably pop that code off in an hour or two, it isn’t that hard. Also my tool is designed for demos, and doesn’t run in the background, but clearly you could have it running all the time, adjusting things based on tags or even attributes of software deployed in the instance. Security automation is insanely powerful. It can completely automate complex security tasks, or, as in Andrew’s example, supplement manual activities and policy changes. Hopefully my snippets give you some ideas, and pop me over any good examples if you are willing to share.
