Why Directly Storing Uploads in the Database Is Risky

• 2018/08/30

Why saving uploads as-is in the database is dangerous

• A malicious file could be uploaded and compromise the entire database.
• If malware is embedded, the whole system can be taken over.
• Accepting extensions you do not anticipate increases the chance of someone uploading a virus.
• Attackers can intentionally upload very large files and trigger server-side latency.

Behavior at upload time

• Validate file extensions on the client with JavaScript before the upload (but never rely on it—users can disable JS, so always validate on the server as well).
• Configure a temporary storage location so the OS can run a virus scan before you persist the file for good.
• If malware is found, discard the file immediately.

In closing

• Extensions are easy to fake, so stay vigilant!