OpenParable
Skip to content
← Back to skills

Cis Azure Compute 2.3.17

DevOps & Security
cis-azure-compute-2.3.17

Cis Azure Compute 2.3.17 is an Agent Skill for devops & security published in the CyberStrikeus/CyberStrike repository on GitHub: a SKILL.md instruction file an AI agent can load to do this task.

Ensure cross-origin resource sharing does not allow all origins

View on GitHub ↗
QUICK START

How to use this skill

Bring this guide into your coding agent with a prompt tailored to the tool you use.

  1. Open your project in Codex.
  2. Copy and paste the prompt below.
  3. Review files and risks before approving any action.
Prompt to paste
Inspect the Agent Skill at https://github.com/CyberStrikeus/CyberStrike/blob/HEAD/.cyberstrike/skill/CIS_benchmarks/Cloud_Providers/Microsoft_Azure/CIS_Microsoft_Azure_Compute_Services_Benchmark_v2.0.0/cis-azure-compute-2.3.17/SKILL.md and all supporting files. Report provenance, permissions, scripts, dependencies, and security risks. Propose an exact installation into .agents/skills/cis-azure-compute-2-3-17, but wait for my approval before writing files or running scripts.

Copying this prompt does not install or run the skill. Review third-party files before use.

Ensure cross-origin resource sharing does not allow all origins

Description

Cross-origin resource sharing (CORS) is a security feature that controls how applications interact with resources hosted on different domains.

Rationale

Restrict CORS to only trusted origins to help enforce proper access control and reduce exposure to malicious cross-origin requests.

Impact

Configuration is required to ensure that the appropriate origins have access.

Setting up a proper CORS policy can be fairly complex and an incorrect setting could permit Cross-Site Request Forgery (CSRF). The "caveat" is that if the app being deployed is a PUBLIC API, a wildcard "*" CORS policy is absolutely necessary.

Audit Procedure

Using Azure Portal

  1. Go to App Service or Function App.
  2. Click the name of a function app.
  3. Under API, click CORS.
  4. Ensure Allowed Origins does not include *.
  5. Repeat steps 1-4 for each function app.

Using Azure CLI

Run the following command to list function apps:

az functionapp list

For each function app, run the following command to get the CORS allowed origins setting:

az functionapp show --resource-group <resource-group-name> --name <function-app-name> --query siteConfig.cors.allowedOrigins

Ensure that the response does not include *.

Expected Result

The CORS allowed origins should not include a wildcard * entry.

Remediation

Using Azure Portal

  1. Go to App Service or Function App.
  2. Click the name of a function app.
  3. Under API, click CORS.
  4. Under Allowed Origins, delete the entry that equals *.
  5. Specify the origins that should be allowed to make cross-origin calls.
  6. Click Save.
  7. Repeat steps 1-6 for each function app requiring remediation.

Using Azure CLI

For each function app requiring remediation, run the following command to remove the wildcard origin:

az functionapp cors remove --resource-group <resource-group-name> --name <function-app-name> --allowed-origins "*"

Use the following command to specify the origins that should be allowed:

az functionapp cors add --resource-group <resource-group-name> --name <function-app-name> --allowed-origins <allowed-origins>

Default Value

By default, Allowed Origins is set to https://portal.azure.com.

References

  1. https://learn.microsoft.com/en-gb/azure/app-service/app-service-web-tutorial-rest-api
  2. https://learn.microsoft.com/en-us/cli/azure/functionapp/cors
  3. https://cheatsheetseries.owasp.org/cheatsheets/HTTP_Headers_Cheat_Sheet.html
  4. https://developer.mozilla.org/en-US/docs/Web/HTTP/Guides/CORS
  5. https://cheatsheetseries.owasp.org/cheatsheets/Cross-Site_Request_Forgery_Prevention_Cheat_Sheet.html

Profile

Level 2 | Automated