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GCP - Serverless Code Exec Services Enumeration
Cloud Functions
Google Cloud Functions allow you to host code that is executed when an event is triggered, without the requirement to manage a host operating system. These functions can also store environment variables to be used by the code.
# List functions
gcloud functions list
# Get function config including env variables
gcloud functions describe [FUNCTION NAME]
# Get logs of previous runs
# By default, limits to 10 lines
gcloud functions logs read [FUNCTION NAME] --limit [NUMBER]
App Engine Configurations
Google App Engine is another "serverless" offering for hosting applications, with a focus on scalability. As with Cloud Functions, there is a chance that the application will rely on secrets that are accessed at run-time via environment variables. These variables are stored in an app.yaml file which can be accessed as follows:
# First, get a list of all available versions of all services
gcloud app versions list
# Then, get the specific details on a given app
gcloud app describe [APP]
Cloud Run Configurations
Google Cloud Run is another serverless offer where you can search for env variables also. Cloud Run creates a small web server, running on port 8080, that sits around waiting for an HTTP GET request. When the request is received, a job is executed and the job log is output via an HTTP response.
The access to this web server might be public of managed via IAM permissions:
# First get a list of services across the available platforms
gcloud run services list --platform=managed
gcloud run services list --platform=gke
# To learn more, export as JSON and investigate what the services do
gcloud run services list --platform=managed --format=json
gcloud run services list --platform=gke --format=json
# Attempt to trigger a job unauthenticated
curl [URL]
# Attempt to trigger a job with your current gcloud authorization
curl -H \
"Authorization: Bearer $(gcloud auth print-identity-token)" \
[URL]