Build a Malware Scanning Solution in AWS

What this lab covers

You combine several AWS services into a working control: uploads land in storage, an event triggers processing, files are scanned, and the result determines whether they are released or quarantined.

The value is in the assembly. Each service is simple on its own, and connecting them correctly, with the right permissions and the right failure behavior, is the skill that transfers to every other piece of cloud engineering you do.

It assumes no prior AWS experience and suits engineers as much as security practitioners. If you have ever wondered what your platform team actually does with Lambda, this is a concrete example.

How event-driven security controls work

S3 emits events when objects are created, and those events can invoke a function directly or pass through a queue or topic. This is the mechanism behind most cloud automation, and once you have used it, a great deal of AWS architecture becomes legible.

The function receives the event, retrieves the object, evaluates it and acts on the outcome. The interesting design decisions are around failure: what happens when the scanner is slow, when the file is enormous, when processing fails, and whether the object is available to users while any of that is happening.

Quarantine is usually implemented as movement between buckets with different access, so an unscanned or failed object is never in a location the application serves from. That separation is what makes the control meaningful rather than advisory.

What you gain from building it yourself

You end up understanding the permission model properly. Wiring events, functions and buckets together forces you to work out which identity needs which permission on which resource, which is exactly the knowledge that prevents over-permissioned roles elsewhere.

You also learn where the failure modes live. A control that silently stops working is worse than no control, and building one makes the monitoring requirements obvious in a way that reading about them does not.

Commercial products exist for this and are often the right answer at scale. Having built the primitive version, you can evaluate them properly, because you know what the hard parts actually are and which claims matter.

Extending the pattern

The same architecture handles a wide range of tasks. Classifying uploads, extracting metadata, enforcing file type restrictions, redacting documents, generating thumbnails and validating structure all follow the identical event, process, decide, act shape.

It applies to security operations too. The pattern behind auto-remediation, where a configuration change emits an event that triggers a corrective function, is the one you have just built with a different trigger and a different action.

Cost and scale behavior are worth understanding while the example is small. Per-invocation pricing, concurrency limits and object size constraints all bite differently at volume, and they are much easier to reason about once you have run the thing.

Applying this at work

• Check whether your applications scan uploaded files at all, and where an unscanned file is reachable from before any evaluation happens.
• Confirm quarantined or unprocessed objects are stored somewhere your application cannot serve from.
• Add monitoring for the control itself, so a scanner that stops working raises an alert rather than silently passing everything.
• Review the permissions on your event-driven functions, which frequently hold more than the specific object access they need.
• Apply the same pattern to one manual security task you currently perform after the fact.

Frequently asked questions

Why scan files at upload rather than at download?

Because an unscanned file sitting in storage may be reachable by other paths, and because scanning once at ingest is cheaper and more predictable than scanning on every retrieval. It also means quarantine happens before anyone can access the object.

What happens if the scanner fails?

That is the central design decision. A control that releases files when processing fails provides very little assurance, so unprocessed objects should remain in a location the application cannot serve from until evaluation succeeds.

Should I build this or buy it?

At scale a commercial product is often the right answer. Building the primitive version first means you can evaluate those products properly, because you understand which parts are genuinely difficult.

Do I need my own AWS account to practice this?

No. The lab runs in a live AWS environment that Pwned Labs provisions for you, so there is nothing to set up and no risk to your own infrastructure.

Which certification covers this in depth?

The Amazon Cloud Red Team Professional (ACRTP) covers AWS attack and detection paths in full, including IAM abuse and privilege escalation, and is assessed hands-on in a live AWS account.