Connecting to an instance and attaching volumes

Connecting to your instance

By now we should have at least one analysis system in our AWS platform for capturing evidence. We will now need to connect through to this system using our key files so we can configure extra storage and with some analysis tools.

If you haven’t already configured key pairs yet you can access these from the EC2 ‘Network and Security’ menu. It goes without saying that once created you should guard your key file with your life.

Once we have our SSL key file, we can follow the standard AWS process for connecting to our instance.

For Linux instances via SSH:

Or for Windows instances via RDP:

Attaching Volumes

As previously discussed, we can attach storage volumes for evidence while configuring our instance or create these after the fact through the ‘Volumes’ menu in EC2. We can also use this method to attach a snapshot as a volume to our analysis instance for imaging.

As with creating new instances, you will want to record the volume name and assign it some tags for tracking storage volumes. You may also wish to use this feature for evidence naming later on when you are acquiring evidence from AWS.

Once you have your volume created you can choose the instance for which to attach it. This is done by selecting the ‘Actions’ button from the ‘Instances’ menu in EC2.

It should be noted that physical device names will need to be defined based on whether your systems are Windows or Linux.

Our block device should now be attached to our Ubuntu instance now and we can query that by listing block devices in our instance.

As our instances are virtual in AWS the Xen storage device format is used (this caught me out the first time around). Our last task will be to create a file system on our block device.

Once we have our new evidence storage volume attached we can create a mount point and mount our block device.

That’s about it, we now have an Ubuntu instance configured with a secondary EXT4 storage volume which can be used as a target disk for forensic images or for storing other files/forensic tools for analysis.

Next up, taking snapshots of existing volumes attaching AWS volumes for forensic imaging.

Reference:

https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/ec2-key-pairs.html

https://tools.ietf.org/html/rfc1421

https://tools.ietf.org/html/rfc1424

https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/ebs-creating-snapshot.html

https://askubuntu.com/questions/166083/what-is-the-dev-xvda1-device#166087

My last blog post covered some initial things you might run into when choosing to setup analysis systems in the AWS cloud infrastructure.

Since that last writing, I have had some new experiences in capturing evidence across multiple regions and availability zones in AWS, which has certainly given me some new insight which I can share and hopefully be of some use.

Launching an Instance

In AWS EC2 an instance is just a virtual machine, there are a number of host operating systems and configurations available depending on your use requirements. For the purposes of performing evidence collection or analysis in AWS, you should at least have a system with enough storage attached to capture your evidence. Again, the requirements for your evidence collection may change depending on the type of case you are working on, the locations of these evidence sources and other factors, such as time.

To spin up a system, it is as easy as logging into the EC2 console and choosing the instances menu and your AMI image which is a system image with varying host Operating Systems.

It’s worth noting at this point that there is the option to select “Free tier only”. If you, like me, are a skinflint, this is the one for you.

Once you have decided on your AMI, this is when you can choose the hardware configuration of your system.

Try not to get too carried away here…

The next thing we need to do is configure instance details which relate to Networking, scaling, IAM roles and monitoring.

I’m not going to cover everything on this screen but will drop some links for extra reading.

At a very basic level, the options I would pay attention to are:

1: Shutdown behaviour. If you wish to terminate your instance when it is shut down this will erase storage on any local drives. Probably not best to set this if you’re looking to preserve evidence. Great for an attacker.

2: Enable Termination protection. See above.

3: Cloudwatch Monitoring. Cloudwatch is essentially the equivalent of a console access logging and firewall service. Logs from this are highly valuable when investigating as they can show uploads and access to instances or volumes as well as access to the AWS console itself.

While using AWS for performing any forensic analysis or evidence collection, you should absolutely have this turned on. Auditing and logging of your analysis and processes can be assisted massively with this functionality.

4: Tenancy. The option over tenancy may be something you need to consider for legal parameters as this relates to the shared physical storage devices in the data centre where your instance will reside.

Once we have these configurations, we can move onto adding our storage.

The initial configuration for an Ubuntu AMI in the free tier is 8gb storage. Increasing the boot volume size to at least large enough to store your tools and dependencies is fairly obvious. I’d also attach a volume here to capture evidence to and consider changing the options for “delete on termination”. You can attach and detach volumes later on so if you’re uncertain at this point it is safe to continue without. Encryption of your volume should be fairly self-explanatory.

Creating and adding tags is something I would consider in depth at the earliest outset while scoping your evidence. This is similar to having a naming convention for internal systems in an office or naming evidence exhibits in a case and I found this the best method for maintaining continuity in both of these areas in AWS.

Lastly, we want to lock down access to our instance which is done through “Security Groups”. Security Groups essentially allow us to implement firewall rules to block or allow certain types of traffic via defined IP’s, CIDR blocks, ports and protocols.

For my instance, I have configured the security group to only allow access from my own IP at home and at work.

Once we review our instance we can hit launch and within a few minutes we will have our system up and running. Always remember to shut down your instances when not in use, this can become quite a costly affair for the higher spec instances.

 

So that’s about it for spinning up your first AWS instance, next I’ll cover how to connect into your instances using different methods.

Reference:

https://aws.amazon.com/autoscaling/

https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/using-spot-instances.html?icmpid=docs_ec2_console

https://aws.amazon.com/documentation/vpc/

https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/iam-roles-for-amazon-ec2.html?icmpid=docs_ec2_console

Initial Account Setup

Emerging Cloud technologies like Amazon Web Services (AWS) are going to change the face of traditional forensics forever. Soon, we will rarely get our hands on physical evidence sources attached to systems like this. This leaves a large number of uncertainties surrounding evidence handling, continuity, security and legal permissions both home and overseas.

Hopefully, this series of posts will help navigate through the acquisition and analysis of these sources.

Some quick observations on account creation:

• I used a protonmail account to sign up for AWS. (It’s quite common for online services to block protonmail accounts for signup nowadays)
• You must provide a full address and credit card details for account creation. (Amazon will have this on record if you have the legal authority to request when investigating)
• Amazon uses their own terminology for everything and there’s a bit to learn if you have no previous experience.
• It looks strangely like the Kindle store.

Anyway… AWS comes in three different flavours as you can see below: (I chose the cheapest Basic Plan, cause I’m a skinflint)

Elastic Cloud 2 (EC2) is the service I chose once I selected my plan. Although the LightSail service may provide similar capabilities, I’ll just focus on EC2.

Before you go any further, this is a good point to make some initial assessments.

1: Pricing, what is your budget going forward?

I found that information relating to this was difficult to find prior to punching in the credit card details. I have included at the end of this post the pricing (AUD) for various hardware configurations and data throughput costs as of 28 May 2018.

2: What type of evidence are you analysing and how?

This could range from large batches of server logs, another AWS instance, volume or image. Perhaps you have a forensic image that you already acquired and uploaded for analysis. You may be trying to ascertain successful logons to the AWS platform itself.

It is extremely important at this stage to determine your host OS and the physical characteristics of your instance, such as memory, VCPU’s and storage.

Gaining an understanding of your evidence sources, analysis tools, the load on system resources and the potential size of any exports will help you figure out your AWS configuration.

3: Where is your target evidence located?

Amazon splits web services into international regions and if you wish to analyse a snapshot of another AWS instance, you will need to ensure your analysis instance is hosted within that same region.

I’m not sure of the cost or time implications of transfer between regions but I have been advised this does involve a physical move of data across regions to different data centres.

4: How do you secure the environment and, in turn, your evidence?

Amazon has a number of measures in place to ensure the environment is secure. This includes sys logging for your instances, advanced monitoring (a pay for service) and EC2 key pairs where the .pem private key file can be used for SSH connectivity.

There is also multi-factor authentication through Google authenticator or similar mobile applications and the ability to lock down access to your instance by specific IP addresses and ports. These are just a few suggestions, there are many other factors you may need to consider along the way.

If at this juncture, you are wondering why on earth would I use a system in AWS to perform forensics then I’ll direct you to the general purpose pricing models below where you can check some of the tech specs of the servers!

Next up… I’ll cover how to launch an AWS instance.

AWS Pricing

General Purpose – Current Generation

	vCPU	ECU	Memory (GiB)	Instance Storage (GB)	Linux/UNIX Usage
t2.nano	1	Variable	0.5	EBS Only	$0.0073 per Hour
t2.micro	1	Variable	1	EBS Only	$0.0146 per Hour
t2.small	1	Variable	2	EBS Only	$0.0292 per Hour
t2.medium	2	Variable	4	EBS Only	$0.0584 per Hour
t2.large	2	Variable	8	EBS Only	$0.1168 per Hour
t2.xlarge	4	Variable	16	EBS Only	$0.2336 per Hour
t2.2xlarge	8	Variable	32	EBS Only	$0.4672 per Hour
m5.large	2	10	8	EBS Only	$0.12 per Hour
m5.xlarge	4	15	16	EBS Only	$0.24 per Hour
m5.2xlarge	8	31	32	EBS Only	$0.48 per Hour
m5.4xlarge	16	61	64	EBS Only	$0.96 per Hour
m5.12xlarge	48	173	192	EBS Only	$2.88 per Hour
m5.24xlarge	96	345	384	EBS Only	$5.76 per Hour
m4.large	2	6.5	8	EBS Only	$0.125 per Hour
m4.xlarge	4	13	16	EBS Only	$0.25 per Hour
m4.2xlarge	8	26	32	EBS Only	$0.5 per Hour
m4.4xlarge	16	53.5	64	EBS Only	$1 per Hour
m4.10xlarge	40	124.5	160	EBS Only	$2.5 per Hour
m4.16xlarge	64	188	256	EBS Only	$4 per Hour

Data Transfer IN To Amazon EC2 From	Pricing
Internet	$0.000 per GB
Another AWS Region (from any AWS Service)	$0.000 per GB
Amazon S3, Amazon Glacier, Amazon DynamoDB, Amazon SES, Amazon SQS, or Amazon SimpleDB in the same AWS Region	$0.000 per GB
Amazon EC2, Amazon RDS, Amazon Redshift and Amazon ElastiCache instances or Elastic Network Interfaces in the same Availability Zone
Using a private IPv4 address	$0.000 per GB
Using a public or Elastic IPv4 address	$0.010 per GB
Using an IPv6 address within the same VPC	$0.000 per GB
Using an IPv6 address from a different VPC	$0.010 per GB
Amazon EC2, Amazon RDS, Amazon Redshift and Amazon ElastiCache instances or Elastic Network Interfaces in another Availability Zone or peered VPC in the same AWS Region	$0.010 per GB

Data Transfer OUT From Amazon EC2 To Internet	Pricing
First 1 GB / month	$0.000 per GB
Up to 10 TB / month	$0.140 per GB
Next 40 TB / month	$0.135 per GB
Next 100 TB / month	$0.130 per GB
Next 350 TB / month	$0.120 per GB
Next 524 TB / month	Contact Us
Next 4 PB / month	Contact Us
Greater than 5 PB / month

Reference:

https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/ec2-key-pairs.html

https://aws.amazon.com/iam/details/mfa/