Shifting Terraform security left

Shifting Terraform security left

How do you know if the HCL you're writing will result in secure infrastructure? How can you write tests to catch common problems? One of the advantages of infrastructure as code is that we can reason about the code before we run it. In this talk we'll look at the area of configuration security, discuss some of the issues around static analysis of Terraform and look at some open source tools that can help with testing your Terraform code.

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Gareth Rushgrove

February 20, 2020
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Transcript

  1. 6.

    Some kind of misconfiguration is encountered on an penetration test

    over 96% of the time. “ “ Configuration is a security risk
  2. 7.

    While CSPs often provide tools to help manage cloud configuration,

    misconfiguration of cloud resources remains the most prevalent cloud vulnerability “ “ Configuration is a security risk
  3. 11.

    Static analysis Static program analysis is the analysis of computer

    software that is performed without actually executing programs
  4. 13.

    The importance of fast feedback Acceptance tests Unit tests Integration

    tests Static analysis Fast Middling Slow Slower
  5. 14.

    Insecure Terraform Can you spot issues in the following code?

    resource "aws_security_group_rule" "my-rule" { type = "ingress" cidr_blocks = ["0.0.0.0/0"] } resource "aws_alb_listener" "my-alb-listener" { port = "80" protocol = "HTTP" } resource "aws_db_security_group" "my-group" { } resource "azurerm_managed_disk" "source" { encryption_settings { enabled = false } }
  6. 15.

    Insecure Terraform Can you spot issues in the following code?

    resource "aws_security_group_rule" "my-rule" { type = "ingress" cidr_blocks = ["0.0.0.0/0"] } resource "aws_alb_listener" "my-alb-listener" { port = "80" protocol = "HTTP" } resource "aws_db_security_group" "my-group" { } resource "azurerm_managed_disk" "source" { encryption_settings { enabled = false } } Wide open ingress rule
  7. 16.

    Insecure Terraform Can you spot issues in the following code?

    resource "aws_security_group_rule" "my-rule" { type = "ingress" cidr_blocks = ["0.0.0.0/0"] } resource "aws_alb_listener" "my-alb-listener" { port = "80" protocol = "HTTP" } resource "aws_db_security_group" "my-group" { } resource "azurerm_managed_disk" "source" { encryption_settings { enabled = false } } Use of unencrypted transport protocol
  8. 17.

    Insecure Terraform Can you spot issues in the following code?

    resource "aws_security_group_rule" "my-rule" { type = "ingress" cidr_blocks = ["0.0.0.0/0"] } resource "aws_alb_listener" "my-alb-listener" { port = "80" protocol = "HTTP" } resource "aws_db_security_group" "my-group" { } resource "azurerm_managed_disk" "source" { encryption_settings { enabled = false } } Unencrypted storage
  9. 20.

    Terrascan Project overview A collection of security and best practice

    tests for static code analysis of terraform templates using terraform_validate. Active, started 4 months ago 333 Python 35 rules, mainly for AWS @cesar-rodriguez Ran 16 tests in 0.015s OK Processed 19 files in C:\DEV\terraforms\backends\10-network-analytics Results (took 1.08 seconds): Failures: (2) [high] [aws_dynamodb_table.encryption.server_side_encryption.ena [high] [aws_s3_bucket.noEncryption] should have property: 'server Errors: (0)
  10. 22.

    Terrafirma Project overview Terrafirma is a Terraform static analysis tool

    designed for detecting security misconfigurations. Inactive, created 2 years ago 17 Python 14 rules, mainly for GCP --- ISSUE FW_1 - Source range open to Internet - SEVERITY WARN - RESOURCE example_fw_rule.google_compute_firewall --- ISSUE FW_2 - SSH Open - SEVERITY INFO - RESOURCE example_fw_rule.google_compute_firewall
  11. 24.

    Checkov Project overview Checkov is a static code analysis tool

    for infrastructure as code. It scans cloud infrastructure managed in Terraform and detects misconfigurations. Active, created 3 months ago 511 Python 50 rules, for AWS, Azure and GCP @schosterbarak, @tronxd, @guyeisenkot, @nimrodkor Passed checks: 4, Failed checks: 0, Skipped checks: 0 Check: "Ensure all data stored in the S3 bucket is securely encrypted at rest" PASSED for resource: aws_s3_bucket.foo-bucket File: /example.tf:1-25 Check: "Ensure the S3 bucket has access logging enabled" PASSED for resource: aws_s3_bucket.foo-bucket File: /example.tf:1-25
  12. 26.

    tfsec Project overview tfsec uses static analysis of your terraform

    templates to spot potential security issues - Checks for sensitive data inclusion across all providers - Checks for violations of AWS, Azure and GCP security best practice recommendations - Scans modules (currently only local modules are supported) - Evaluates expressions as well as literal values Active, started 4 months ago 927 35 rules, mainly for AWS @liamg
  13. 27.

    tfsec Detect common configuration issues $ tfsec 5 potential problems

    detected: Problem 1 [AWS018][ERROR] Resource 'aws_security_group_rule.my-rule' should include a description for auditing purposes. /Users/garethr/Documents/terraform-security/main.tf:1-4 1 | resource "aws_security_group_rule" "my-rule" { 2 | type = "ingress" 3 | cidr_blocks = ["0.0.0.0/0"] 4 | } 5 | 6 | resource "aws_alb_listener" "my-alb-listener"{ 7 | port = "80" See https://github.com/liamg/tfsec/wiki/AWS018 for more information. Problem 2 [AWS006][WARNING] Resource 'aws_security_group_rule.my-rule' defines a fully open ingress security group rule. /Users/garethr/Documents/terraform-security/main.tf:3 Decision (any JSON value)
  14. 29.

    Conftest Project overview Write tests against structured configuration data using

    the Open Policy Agent Rego query language. - Currently supports YAML, JSON, INI, TOML, HOCON, HCL, CUE, Dockerfile, HCL2, EDN, VCL and XML - Share policies using OCI registries, Git, S3 - Built-in debugging and testing tools Active, started 10 months ago 828 Write your own rules @garethr, @jpreese, @blokje5, @boranx, @KeisukeYamashita, @xchapter7x, @proplex, ...
  15. 30.

    Conftest Running tests against your configuration $ conftest test -i

    hcl2 main.tf FAIL - main.tf - ALB `my-alb-listener` is using HTTP rather than HTTPS FAIL - main.tf - ASG `my-rule` defines a fully open ingress FAIL - main.tf - Azure disk `source` is not encrypted Decision (any JSON value)
  16. 31.

    What is Open Policy Agent? github.com/open-policy-agent/opa Service OPA .rego Query

    (any JSON value) Decision (any JSON value) Data (JSON) Policy (Rego) Request, Event, etc. - An open source policy engine - Written in Go - WebAssembly support coming along - A CNCF project - Usable as a library and a service - A vibrant open source community - Provides a declarative DSL for writing policy called Rego
  17. 32.

    Conftest Write assertions in Rego package main deny[msg] { proto

    := input.resource.aws_alb_listener[lb].protocol proto == "HTTP" msg = sprintf("ALB `%v` is using HTTP rather than HTTPS", [lb]) } deny[msg] { rule := input.resource.aws_security_group_rule[name] rule.type == "ingress" contains(rule.cidr_blocks, "0.0.0.0/0") msg = sprintf("ASG `%v` defines a fully open ingress", [name]) }
  18. 33.

    Conftest Write unit tests for Rego in Rego test_blank_input {

    no_violations with input as {} } test_correctly_encrypted_azure_disk { no_violations with input as {"resource": { "azurerm_managed_disk": { "sample": { "enc } test_unencrypted_azure_disk { deny["Azure disk `sample` is not encrypted"] with input as {"resource": { "azurerm_ma }
  19. 35.
  20. 37.

    Cost/benefit Static analysis is cheap to run, but can result

    in false positives and false negatives
  21. 38.

    Developer proximity The closer feedback is provided to the original

    author of the code, the cheaper it should be to address issues
  22. 39.
  23. 40.

    Shift security left Automatically catching security issues during development means

    less issues in production, and more time to focus on finding and fixing them