OSS Bucket Exposure and Access Logging Gap
A security review finds an OSS bucket holding customer invoices is set to public-read. Access logs show 40,000 GET requests from 15 unfamiliar IP ranges over the past week. The bucket has versioning disabled and no lifecycle rules. The application writes invoices via an ECS instance using an AccessKey stored in a config file on disk. The team wants to lock it down immediately without breaking the invoice pipeline, which runs every 10 minutes.
1. Outline the remediation sequence, ordering the steps by risk and reversibility.
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Order matters - stop the bleeding first, then harden, then verify:
- Immediately set the bucket to private and block public access. This is reversible and stops ongoing exposure; the pipeline uses an AccessKey, not public access, so it should keep working.
- Rotate the AccessKey in the config file to a RAM user scoped to only the required OSS actions on this bucket. The current key is on disk and may be compromised.
- Enable versioning and access logging before further changes, so you have an audit trail going forward.
- Review the 40,000 GETs against known customer IPs; treat unfamiliar ranges as a potential data-exposure incident and escalate per policy.
- Add lifecycle rules and consider server-side encryption.
Do not delete objects or disable the pipeline before confirming the private setting didn't break it.
2. Versioning was disabled during the exposure. What does that mean for your incident response, and what would you change going forward?
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Without versioning you cannot tell whether objects were overwritten or deleted by an attacker, and you have no prior versions to restore. You also can't distinguish a legitimate invoice from a tampered one by object history alone.
Incident response implications:
- Rely on access logs and any downstream copies (e.g., the invoicing system's database) to reconstruct what was read vs. modified.
- If integrity is in doubt, treat affected invoices as potentially altered and reconcile against the source system.
Going forward: enable versioning, add MFA-delete for critical buckets, enable access logging and OSS inventory, and use bucket policies that deny public principals. Also move the AccessKey to an instance RAM role so no long-lived secret sits on disk.