On-demand function (serverless): what it is and how it is attacked
A small piece of code that runs only when something asks for it, with no server to look after.
Also known as
- serverless
- Lambda
- Azure Functions
- Cloud Run
- FaaS
Typing any of them into the editor finds this object.
Why it matters on a security diagram
It carries an identity of its own, so what it can reach is settled by permissions rather than by where it sits. It appears on no network diagram and in no server inventory, while holding access that reaches real data.
How it gets attacked, and what reduces it
How it gets attacked
- Permissions attached to the code that are far wider than the job it does
- Set going by content from outside, so untrusted input reaches it directly
- Gone in seconds by design, leaving little behind unless records were arranged in advance
What reduces it
- Scope the identity to the one job, since there is no host to constrain it
- Treat trigger content as untrusted, because that is how it arrives
- Arrange logging in advance; there is nothing to examine afterwards
Where it sits
- Group
- Cloud and subscribed services · Things that only exist because somebody else runs the platform underneath them.
- Whose side, by default
- Ours · Belongs to the organisation the diagram is about.
- Catalogue identifier
- serverless-function
Reviewed . CC BY 4.0.
Others in cloud and subscribed services
- Cloud platformAWS · Azure · GCP · Google Cloud · public cloud · hyperscaler · IaaSA supplier's computing platform, rented by the hour, where a setting made on a website creates or removes a whole system.
- AI model endpointLLM API · inference endpoint · model service · AI serviceWhere an application sends a question, along with documents, images or data, to an AI model and gets an answer back.
- Cloud accountsubscription · project · AWS account · Azure subscription · Google Cloud project · cloud environmentOne named compartment of a cloud platform, with its own bill and its own list of who may change what.
- Cloud account groupmanagement group · AWS Organizations · GCP folder · landing zone · account structureThe parent that owns all of an organisation's cloud accounts and can set rules over every one of them.
- Cloud control panelcontrol plane · management console · cloud portal · cloud API · management planeThe website and commands used to configure the cloud itself, as opposed to the systems running inside it.
- Supplier-run applicationSaaS · software as a service · cloud application · business applicationAn application a supplier runs entirely, which the organisation subscribes to and puts its data into.
- Connected appOAuth application · app registration · enterprise application · app consent · add-inAn outside program that somebody has allowed to reach company data on their behalf.
- Managed databaseRDS · Azure SQL · Cloud SQL · database as a service · DBaaSA database the cloud provider runs, where the data and the settings are yours but the machine is never touched.
- Container platformKubernetes · K8s · cluster · EKS · AKS · GKE · OpenShiftThe system that decides where each packaged application runs, and starts it again when it stops.
- Container image storecontainer registry · image registry · ECR · ACR · artefact storeThe library of packaged applications that machines fetch from whenever they start something.
- Infrastructure blueprintinfrastructure as code · IaC · Terraform · state file · CloudFormation · BicepThe written description of what the cloud should contain, together with the record of what was actually built.
The cloud and subscribed services group lists all 12 of them side by side.
On-demand function on your own diagram
Open the editor, press N, and type serverless. The object is placed and connected to whatever was selected, and Tab adds the next one already joined to it. Nothing is uploaded: the page is served with a Content Security Policy that forbids the browser from making any outbound request at all.
Open the diagram maker