Skip to main content

Securing Terraform and You Part 1 -- rego, Tfsec, and Terrascan

9/20: The open source version of Terraform is now OpenTofu 

 

Sometimes, I write articles even when things don't work. It's about showing a learning process.

 Using IaC means consistency, and one thing you don't want to do is have 5 open S3 buckets on AWS that anyone on the internet can reach. 

That's where tools such as Terrascan and Tfsec come in, where we can make our own policies and rules to be checked against our code before we init.

 As this was contract work, I can't show you the exact code used, but I can tell you that this blog post by Cesar Rodriguez of Cloud Security Musings was quite helpful, as well as this one by Chris Ayers.

The issue is using Rego; I found a cool VS Code Extension; Terrascan Rego Editor, as well as several courses on Styra Academy; Policy Authoring and Policy Essentials.

The big issue was figuring out how to tell Terrascan to follow a certain policy; I made it, put it in a directory, and ran the program while in that directory, and it didn't seem to see it.

If you need help, check out Styra Acdemy's OPA courses (Free!) and joining the Slack. Anders Eknertalso helped quite a lot!

 rego is probably excellent for those who know their way around a programming language, but I kept coming across some many different ways to stylize it, I got confused, and not yet having the knowledge on where the program should be looking made rego frustrating. 

There must be a command to allow Terrascan to check for a policy in the active directory -- I just haven't found it yet.

But somehow, the syntax still wasn't clicking for me; So I went back to Chris Ayers' series about it and decided to try tfscan by Aqua instead.

Look at this syntax; The fact that it took a few hours instead of the weeks of poking at rego to solve my problem is amazing. A small sample is below:

---
checks:
- code: CUS001
description: Custom check to ensure the CostCentre tag is applied to EC2 instances
impact: By not having CostCentre we can't keep track of billing
resolution: Add the CostCentre tag
requiredTypes:
- resource
requiredLabels:
- aws_instance
severity: ERROR
matchSpec:
name: tags
action: contains
value: CostCentre
errorMessage: The required CostCentre tag was missing
relatedLinks:
- http://internal.acmecorp.com/standards/aws/tagging.html

That's YAML! I remember it looking different when using CloudFormation templates. You make it, make sure it ends in _tfchecks.yaml (or .json), and put it in the .tfsec root check path -- and if you want to test it quickly without looking for that path, use tfsec --custom-check-dir . to run it in your current directory.

 I was getting the error even when my buckets fit the criteria, and when I asked for help on Twitter, I was told that, essentially, tfsec had been integrated into Trivy, and would not be updated anymore, a little more than a year after they bought tfsec. 

The GitHub announcement page has a chorus of thumbs-down in response. It's a real pity support has been dropped for something that almost worked perfectly out of the box.

More to come.


If any of this helps you, give this post a share.


Comments

Popular posts from this blog

Making KPI Dashboards with PowerBI

 While this is the free tier, I cannot share or collaborate with others, nor can I publish content to other people's workspaces, but they will not stop me from screenshooting and recording these self-taught adventures,so! I'm doing this because I idly searched "Mattel careers" and "Information Technology", and seeing a bulletpoint saying the following: Analytical and reporting skills such as creating dashboards and establishing KPIs such as experience with PowerBI, Cognos, Tableau, and Google Data Lake/AWS is preferred And thought "Well, I've used Tableau, and I've heard about PowerBI,  even if its in-demandness is questionable , so how similar is it? And can I write about it?"  First, PowerBI (PIB) does have a downloadable, local version, but apparently Windows-only. I could download the .exe but I couldn't run it / drag it to applications on my MacBook.  Not a problem, we'll use the online SaaS version, and a dataset found here, ...

Log Sorting with AWS CloudWatch, AWS CloudWatch Insights

 The cool thing is, I was contracted to make these videos in collaboration with CloudAvail Technology Consulting to help people decide which service they wanted to use for their logging - AWS CloudWatch, AWS CloudWatch Insights, DataDog, or New Relic. I'm searching through nginx logs. I have accompanying videos of each service that you can find on the CloudAvail Youtube page; See these links to go to the DataDog and NewRelic posts.   The idea was to be subjective in the videos, but I can be objective on my personal blog.     CloudWatch     The syntax is odd, but easy to grasp. Sort log data by IP addresses, message codes, and status codes. The simplest query system, but not quite robust.   Insights       The syntax has changed - Vastly. I see major SQL influences. You can see that in how the parse function works - in this case, it's often taken pieces of a pre-existing standard - in this case, message - and breaking them into their own c...

Connecting IoT Devices to a Registration Server (Packet Tracer, Cisco)

 If you're seeing this post, I'm helping you, and you probably have LI presence: React and share this post to help me in return.   In Packet Tracer, a demo software made by Cisco Systems. It certainly has changed a lot since 2016. It's almost an Olympic feat to even get started with it now, but it does look snazzy. This is for the new CCNA, that integrates, among other things, IoT and Automation, which I've worked on here before. Instructions here . I don't know if this is an aspect of "Let's make sure people are paying attention and not simply following blindly", or an oversight - The instructions indicate a Meraki Server, when a regular one is the working option here. I have to enable the IoT service on this server. Also, we assign the server an IPv4 address from a DHCP pool instead of giving it a static one. For something that handles our IoT business, perhaps that's safer; Getting a new IPv4 address every week or so is a minimal step against an...