Inspecting the AWS RDS CA Certificates

Trying to fetch all the RDS CA certificates as a bundle, and inspect them:

# vim: tabstop=8 expandtab shiftwidth=4 softtabstop=4
import urllib.request
import re
from OpenSSL import crypto
from datetime import datetime

def get_certs():
    url = (""
    with urllib.request.urlopen(url=url) as f:
        pem_certs = []
        current_cert = ''
        for line in'utf-8').splitlines():
            current_cert = current_cert + line + "\n"
            if re.match("^-----END CERTIFICATE-----", line):
                current_cert = ""
        return pem_certs

def validate_certs(certs):
    ca = None
    for cert_pem in certs:
        cert = crypto.load_certificate(crypto.FILETYPE_PEM, cert_pem)
        if cert.get_issuer().CN == cert.get_subject().CN:
            ca = cert
    for cert_pem in certs:
        cert = crypto.load_certificate(crypto.FILETYPE_PEM, cert_pem)
        start_time = datetime.strptime(
            cert.get_notBefore().decode('utf-8')[0:14], "%Y%m%d%H%M%S")
        end_time = datetime.strptime(
            cert.get_notAfter().decode('utf-8')[0:14], "%Y%m%d%H%M%S")
        print("%s: %s (#%s) exp %s" %
              (cert.get_issuer().CN, cert.get_subject().CN,
               cert.get_serial_number(), end_time))
        if end_time <
            print("EXPIRED: %s on %s" % (cert.get_subject().CN,
        if start_time >
            print("NOT YET ACTIVE: %s on %s" % (cert.get_subject().CN,

pem_certs = get_certs()


Today this gives me::

Amazon RDS Root CA: Amazon RDS Root CA (#66) exp 2020-03-05 09:11:31
Amazon RDS Root CA: Amazon RDS ap-northeast-1 CA (#68) exp 2020-03-05 22:03:06
Amazon RDS Root CA: Amazon RDS ap-southeast-1 CA (#69) exp 2020-03-05 22:03:19
Amazon RDS Root CA: Amazon RDS ap-southeast-2 CA (#70) exp 2020-03-05 22:03:24
Amazon RDS Root CA: Amazon RDS eu-central-1 CA (#71) exp 2020-03-05 22:03:31
Amazon RDS Root CA: Amazon RDS eu-west-1 CA (#72) exp 2020-03-05 22:03:35
Amazon RDS Root CA: Amazon RDS sa-east-1 CA (#73) exp 2020-03-05 22:03:40
Amazon RDS Root CA: Amazon RDS us-east-1 CA (#67) exp 2020-03-05 21:54:04
Amazon RDS Root CA: Amazon RDS us-west-1 CA (#74) exp 2020-03-05 22:03:45
Amazon RDS Root CA: Amazon RDS us-west-2 CA (#75) exp 2020-03-05 22:03:50
Amazon RDS Root CA: Amazon RDS ap-northeast-2 CA (#76) exp 2020-03-05 00:05:46
Amazon RDS Root CA: Amazon RDS ap-south-1 CA (#77) exp 2020-03-05 21:29:22
Amazon RDS Root CA: Amazon RDS us-east-2 CA (#78) exp 2020-03-05 19:58:45
Amazon RDS Root CA: Amazon RDS ca-central-1 CA (#79) exp 2020-03-05 00:10:11
Amazon RDS Root CA: Amazon RDS eu-west-2 CA (#80) exp 2020-03-05 17:44:42

S3 MFA Delete

The Simple Storage Service (S3, or S3) has made long term durable storage simple for the masses. The democratisation of object storage with well documented, stable APIs has been incorporated into many products. The API is part of the product.

But despite the word Simple, there are more and more advanced features: storage tiers, security policies, life-cycle policies, logging, versioning, requestor-pays, and more recently, Inventory generation and more.

S3 features prominently in long-term retention of important data due to its high durability. But today I’m diving into the another benefit: MFA Delete.

Simple CRUD

Create, Read, Update, Delete: the basics of a REST interface for sending and manipulated a data store. In AWS, IAM policy (or Bucket Policy) can permit or limit the actions that a user can perform.  If you delete an Object, then it’s gone. If you overwrite an object (using the same Prefix or name), then the original is lost, as you would expect.

We can limit a calls to s3:DeleteObject, either with a explicit DENY, or carefully only permitting the fine grained controls we intend (s3:PutObject, s3:GetObject) for the role., groups or users we confer privileges to. However, we still run the change of an unintended overwrite.

Furthermore, there may be privileged users or roles that have elevated access, so while your general work-flow is protected by policy from accidental deletion, you’re not protected from accidents from other source (eg, humans with admin privs).

S3 Versioning

To help with this, S3 Versioning permits you to retain multiple revisions of the same object. When listing the bucket naturally, you see the current revision in the list. But a few API calls and you can drill into the previous revisions of the same object, helping you recover from object overwrites.

When a file is deleted from a Versioned S3 Bucket, its really just updated with a new version as a designated Delete Marker. This Marker prevents the object being included in a natural bucket listing. Without further action, the previous versions are still present, and you’re still paying for their storage.

Lifecycle Policies

I always recommend agreeing a life cycle retention policy for S3 buckets – possibly by agreed prefix – upon creation of the Bucket. It makes the creator of the data set really consider how permanent their data must be.

Lifecycle policies can change data storage tiers, but my favourite is the expiry of “previous revisions” after a customer-defined number of days. This gives me a kind of “S3 Undelete” window, and its saved my bacon on several occasions; the accidental Admin delete can easily be undone within the number of days you have specified.

But I want to go further, I want to have some buckets that I know are my “keep forever” bucket, and I want to make any kind of delete of even previous revisions difficult: enter MFA Delete.

Enabling MFA Delete

MFA delete works on Versioned S3 Buckets, and protects all revisions (including delete markers) from being deleted with a corresponding special delete command that includes a valid MFA token from an authorised user.

In my experimentation, I had an existing bucket that I had Versioning enabled. To enable this feature I had to turn to the API – this isn’t available in the AWS Console at this time. I also had to us an IAM User with MFA or the master Root identity – federated users or Ec2 Instances in IAM Roles cannot do this, as they have no MFA associated with them directly.

In this example, I created a profile for the AWS CLI called MasterUser, and had root IAM keys created (which I immediately rescinded). I had a bucket called MyVersionBucket, that I had set up just as I liked it. I also grabbed the ARN of my Virtual MFA I had for the Root user in this account (the ARN is listed as a SERIAL number in the console).

To enable MFA Delete:

aws s3api put-bucket-versioning –profile MasterUser –bucket MyVersionBucket –versioning-configuration MFADelete=Enabled,Status=Enabled –mfa ‘arn:…. 012345

Note: the MFA is referenced with quotes around it, as the single argument contains a space between the serial (ARN in this case) and the current value on the MFA).

To then see the configuration:

aws s3api get-bucket-versioning –profile MasterUser –bucket MyVersionBucket

With this in place it was time to test it out.

(Not really) Deleting from an MFA-Delete protected Bucket

The first thing I did was upload a file (same as normal), and then delete it. Using the “current view” of the bucket, the file vanished. In the new AWS console I could see the deleted item listed, and drilling into it, I could see the revisions there as with a regular Versioning bucket.

The next thing I tried was to “undelete” an object, an option that has just appeared in the revised S3 console, however this silently failed.

I then looked at the revisions of my sample file, and could see the delete marker sitting there. I attempted to delete the Delete Marker, but without an MFA I was blocked. This seemed to make sense: previously “undeleting” an object from S3 meant removing the delete marker, and clearly that’s just a version that I cannot really delete.

I looked at the other revisions of my sample file, and I was likewise blocked from deleting them.

Next looked at adding a Lifecycle policy to the bucket, and discovered that no Lifecycle policies can be added to an MFA protected bucket. So three’s no opportunity to move to the Infrequent Access tier of storage after a period automatically.

To truly empty the bucket, I deleted the a version of the file:

aws s3api delete-object –bucket MyVersionBucket –key sample.png –version-id Foo1234 –mfa ‘arn:… 123456

The VersionID was displayed to me in the list versions’ output.

Of course, I could potentially have suspended MFA delete, tidied up, and then re-enabled it.

At the end of my experiment, with MFA Delete Enabled, I could dimply delete the empty bucket as normal – there were no further challenges.

When to use MFA Delete

As MFA-Delete is a bucket-wide policy, you need to ensure that all objects that will be in this bucket are right to be considered permanent. You’ll want to limit who has access to put-version policy (perhaps your PowerUsers should have an explicit deny on this API call). If you have temporary or staging data in the bucket, or data that you want a lifecycle policy to automaticlaly clean up, then MFA Delete is not for you.

CloudPets security fail is not a Cloud failure

I spent several years at Amazon Web Services as the Solution Architect with a depth in Security in A/NZ. I created and presented the Security keynotes at the AWS Summits in Australia and New Zealand. I teach Advanced Security and Operations on AWS. I have run online share-trading systems for many of the banks in Australia. I help create the official Debian EC2 AMIs. I am the National Cloud Lead for AWS Partner Ajilon, and via Ajilon, I also secure the State Government Land Registry in Ec2 with Advara.

So I am reasonably familiar with configuring AWS resources to secure workloads.

Last week saw a poor security failure; the compromise of a company that makes Internet-connected plush toys for children that lets users record and playback audio via the toys: CloudPets. Coverage from Troy Hunt,  The Register, ArsTechnica.

As details emerged, a few things became obvious. But here are the highlights (low-lights, really) to me that apparently occurred:

  • A production database (MongoDB) was exposed directly to the Internet with no authentication required to query it
  • Audio files in S3 were publicly, anonymously retrievable. However, they were not listable directly (no worries, the object URLs were in that open Mondo database)
  • Non-production and production systems were co-tenanted

There’s a number of steps that should have been taken technically to secure this:

  1. Each device should have had a unique certificate or credential on each of them
  2. This certificate/credential should have been used to authenticate to an API Endpoint
  3. Each certificate/credential could then be uniquely invalidated if someone stole the the keys from it
  4. Each certificate/credential should only have been permitted access to fetch/retrieve its own recordings, not any recording from any customer
  5. The Endpoint that authenticates the certificate should have generated Presigned URLs for the referenced recordings. PreSigned URLs contain a timestamp set in the future, after which the Presigned URL is no longer valid. Each time the device (pet) would want a file, it could ask the Endpoint to generate the Presigned URL, and then fetch it from S3
  6. The Endpoint could rate limit the number of requests per certificate pre minute/hour/day. Eg, 60 per minute (for burst fetches), 200 per hour, 400 per day?

If the Endpoint for the API was an Ec2 instance (or better yet, an AutoScale Group of them), then it could itself be running in the context of an IAM Role, with permission to create these Presigned URLs. Similarly an API Gateway running a Lambda in a Role.

Indeed, that Endpoint would have been what would have used the MongoDB (privately), removing the publicly facing database.

I’ve often quoted Voltaire (or Uncle Ben from Spider Man, take your pick): “with great power comes great responsibility“. There’s no excuse from the series of failures that were conducted here; the team apparently didn’t understand security in their architecture.

Yet security is in all the publicly facing AWS customer documents (joint responsibility). It’s impossible to miss this. AWS even offers a free security fundamentals course, which I recommend as a precursor to my own teachings.

Worse is the response and lack of action from the company when they were alerted last year.

PII and PHI is stored in the cloud. Information that the economy, indeed modern civilisation depends upon. The techniques used to secure workloads are not overly costly, they mostly require knowledge and implementation.

You don’t need to be using Hardware Security Modules (HSMs) to have a good security architecture, but you do need current protocols, ciphers, authentication and authorisation. The protocols and ciphers will change over time, so IoT devices like this need to also update over time to support Protocols and Ciphers that may not exist today. It’s this constant stepping-stone approach, to continually be moving to the next implementation of transport and at-rest ciphers that is becoming a pattern.

Security architecture is not an after-thought that can be left on the shelf of unfulfilled requirements, but a core enabler of business models.

Looking back at 2016, and forward to the future

It’s going to be interesting to see how the Gartner Magic Quadrant for Infrastructure as a Service looks when it comes out this later year (assuming around August time again): the gap between the players, and the names that disappear.

2016 saw 5 competitors drop out compared to Gartner’s 2015 edition, and now more recently Cisco’s $1B investment in Intercloud seems to have ended; however they’ve now purchased AppDynamics who have been pushing very heavily into the cloud, especially around the microservices world. It’s interesting to see the the players shuffle around:

Year Count Differences to previous year
2013 15
2014 15 Merged IBM + Softlayer, -Tier3, -Savis, +VMWare, +Google, +CenturyLink
2015 15 -GoGrid, -HP, +NTT, +Interoute
2016 10 -Joyent, -DimensionData, -Verizon, -CSC, -Interoute

Meanwhile at AWS, services continued to innovate, reliably and without any major interruptions. May 2015 saw VPC S3 Endpoints launched, permitting private interconnect between VPCs and S3 service, and there’s been promises of more of this to follow. Re:Invent 2016 saw enhanced distributed account controls with AWS Organisations being announced (only in preview, so subject to change), enhancing the corporate controls in a multi-AWS-account set-up.

AWS did open up four additional Regions in 2016 as promised — Ohio, Canada, London, and India. The footprint of its Edge Locations also expanded — although some of these were additional Edges in the same cities (at different interconnect/peering providers). That’s OK; as the Edges can be turned on and off transparently around maintenance windows, so having multiple Edges in a location may indicate how important this location is.

I’ve found it particularly interesting to see CloudFront move from a flat network of Points of Presence (POPs), to a two-tier caching model with “Regional Edges” servicing requests from “Global Edges”. As CloudFront has spread wider into more locations, there’s an increase in the number of origin requests (misses) made to your origin service, which even with modest TTLs on objects can still be an overwhelming volume of traffic.

From a networking perspective, the availability of IPv6 on Service Endpoints, and now within the VPC is also a sign of evolution. These EC2 evolutions have happened in the past — perhaps not so noticeable:

  • from 32 bit to 64 bit VMs
  • from Para-Virtualisation (PVM) to Hardware-assisted Vitalisation (HVM) for EC2
  • to newer generations of Instance types (helped by an improved pricing point)

And now we see the start of the move from IPv4 to IPv6. It will take a few years, but we’re standing at the edge of massive change. Yet another migration. Only yesterday have we seen the launch of IPv6 for ELB within VPC – something that used to exist for ELB in what is now called “Classic” (all customer shared networking EC2), and today IPv6 within the VPC in all existing Regions (from what was just US-East-2 at launch; which in itself was interesting to see Ohio uses as a canary for the new feature deployment instead of the traditional US-East-1).

For the Debian the EC2 images that I help maintain, we started to support the Elastic Network Adaptor (ENA) at the end of 2016 after I attended the first Debian Cloud Sprint in Seattle – with thanks to Marcin Kulisz for his assistance. For those not familiar, Debian is a 23 year old non-profit, open-source operating system, which underlies much of the modern Linux ecosystem. I’ve been participating since the late 1990s, and a member of the project since 2000 (18 years now). Today I help maintain the Debian AMIs on EC2 for (at least) tens of thousands of AWS customers (may be much higher).

Debian has been selected to be one of the options of operating system in AWS’s new LightSail product: point-and-click VPS that neatly wraps up the details of VPC, Security Groups and storage into a simple model. This brings the beauty of Debian to even more people, taking away the long-held myth that Linux is hard.

What’s in store for 2017

For Debian: In 2017 we’ll move to make the images even more transparent to consumers than they are now with the help of the very talented maintainer of FAI for the last 20 years or so, Mr Thomas Lange (whom I have had the pleasure of knowing for many of those years since we met at DebConf 1). Marcin Kulisz, Anders Ingemann and others have played a major part in this, and of course, the other 800+ Debian Developers world-wide, and of course the contributors who report bugs, review code and help ensure that Debian remains as transparent as possible and true to its goals.

For the AWS platform, storage pricing continues to drop; and while it took a while to get the cents-per-GB-per-month, I’m sure we’ll see cents-per-TB-per-month not too long from now. Others say Cloud storage will be “free” (little “f”), but I just think the order of magnitude for charging will change. Compute edges down in price too; new instance types will come, and those who architect (and automate) their deployments well (CloudFormation, Auto-scale and Launch Configurations) can and will easily adopt them.

Status Quo: All Change

What’s become clear is that for any cloud deployment, there is constant change and maintenance in order to be able to take advantage of improvements to the platform over time. Be that re-deploying your app servres with new operating system patches, modifying VPC architectures (Endpoints, NAT GW, IPv6), etc. I guess the main things these days is to be pretty comfortable with a quote from Heraclitus (535-475 BC): “Change is the only constant in life“.

Meanwhile, there’s another whole story around my work that’s been very satisfying and exciting, but that’s a story for another day…

If you’re interested in AWS and Security, then please check out my training at, where in a 2 day in-person class we cover above and beyond the AWS courses to ensure you have the knowledge and are prepared for the agile world of running and securing environments in the AWS Cloud.

AWS Zero to Hero in a few hours: Environment creation and Deployment at speed

I had a colleague approach me asking to create a new environment for him. Previously I had helped create a CloudFormation template defining an enterprise VPC, and he had previously created CloudFormation templates for his work loads in his development environment.

I wasn’t intending this to be a race, but it happened pretty quickly as we’d prepared our templates for other environments previously. So starting around 10:30am, here’s what we did:

  1. Create a new email Distribution List for the master (root) account on the corporate mail system.
  2. Sign up a new account, and lock it down. Hardware MFA for the root account, IAM Group (Admins) for local IAM users, and an initial IAM user (me) with MFA turned on for the user. Customer Managed Policy – Administrator access, but with an IP Address Condition – assigned to the IAM Group. Password policy enabled, and SST disabled in all except US East 1 and our commonly used (and closest) Region. Set Challenge Response questions for support, adjust comms preferences (to none).
  3. Configure the SAML (AD FS) provider for the organisation. Create several IAM roles for Web SSO via the SAML IDP: Network team, Security team.
  4. Create an AWS cross-account IAM role for the security account, with read-only privileges. This enables the proactive DevSecOps to kick in.
  5. In our security account we adjusted the S3 Bucket policy to permit the new workload account to log to it. In my billing account, issue a consolidated invite to the new workload account.
  6. Back in my new workload account, accept the Consolidate billing request, and configure Global CloudTrail to the security account bucket above. This then automatically filters to my security log processing and alerting.

By this time it’s around noon, and we were ready to create our VPC. After taking an initial IP allocation from the initial topology (I’ve been using a /20 CIDR block for most VPCs, and either locating a significant workload, or multiple smaller workloads, in each VPC).

I’ve maintained my VPC Template for some time, progressively adding more “baseline” features that I love to have present – and sharing it with those around me to help accelerate (and standardise) their environments):

  • VPC designed across three AZs, but with addressing consistency and space to add a fourth AZ for each allocation, with:
    • A set of subnets for Internal Load Balancers. No route to the Internet for these.
    • A set of (small) subnets for (relational) databases. No route to the Internet here again.
    • A set of subnets for direct Internet access, such as for External Load Balancers and services that are facing the internet directly… routing the internet via the IGW.
    • A NAT Gateway per AZ (housed in the Internet subnets above)
    • A set of subnets for Application servers, using the NAT GW Per AZ. Hence a routing table per AZ.
    • A set of subnets for other “backend” servers, in case there is anything else that we’ll want to segregate out from the Application servers internally.
  • VPC Flow Logging
  • CloudWatch logs group with retention period set
  • SNS Topics for app servers to send default Alerts and Escalations to.
  • VPC Endpoints for S3
  • RDS DB Subnets
  • etc, etc.

The separation of Internal Elastic Load Balancers into their own contiguous CIDR block is to make my life simpler with the traditional on-premise firewalls. Naturally I expose my ELBs to my clients, but I am required to also authorise the on-premise firewall to egress traffic into our VPC. By having one contiguous block, this makes it one destination rule in this legacy equipment by super-netting the three contiguous blocks. For example:

  • ELB in AZ A:
  • ELB in AZ B:
  • ELB in AZ C:
  • Reserved block if there were AZ D:
  • Total range for ELBs in one CIDR:

It’s important to observe the natural block boundaries of CIDR ranges, so choose carefully and use various web tools to help you with address calculations. As noted above, there’s some left over space that I’m not currently allocating: that’s the price to pay for being prepared for the future in an IPv4 world, but its better that than having to re-jig subnets after the workload is live (I’ve had to do this with significant government workloads in order to switch from 2AZs to using 3AZs, but I’m glad I did for several reasons).

After 10 minutes of this VPC creation, we were ready for DirectConnect sub interfaces to drop in, and initial connectivity back to the on-premise network, to be supplemented by a VPN over Internet on a lower priority, preferenced by BGP weightings.

After this came a few S3 buckets: one for holding software and associated ‘artefacts’ for the development cycle, and other for holding logging data (ELB, S3, etc). A quick switch to the Development account and a read-only policy for the Development ‘release’ bucket, and artefacts are ready to be pulled into this Test environment.

After an initial sync, the CloudFormation templates for the EC2-based workloads were ready to roll, with parameters for the new logging destinations, artefact sources from S3 buckets, and subnets options.

By 4pm, the workload was up and stable. Ready for the 6pm call to resize all Autoscale groups to zero, which would be reversed at 6am.

Now this wouldn’t be possible without the support of the networking team looking after the on-premise routers and the direct connect VLAN allocations, or the enterprise server team for creating the email Distribution List, and Claims on the SAML Identity Provider (IDP): it’s as a team we manage to get such velocity at delivery.

But the real key to all of this: templating and automation. Managing changes via a template makes it repeatable; that’s what makes updates to CloudFormation just as exciting for me as updates to the services you can configure yourself via CLI, API or Web Console.

If you’re interested in AWS and Security, then please check out my training at, where in a 2 day in-person class we cover above and beyond the AWS courses to ensure you have the knowledge and are prepared for the agile world of running and securing environments in the AWS Cloud. Every student on our course gets a complementary Gemalto hardware MFA for use with any AWS account.