Netskope debuts as a Leader in the 2024 Gartner® Magic Quadrant™️ for Single-Vendor Secure Access Service Edge Get the report

close
close
  • Why Netskope chevron

    Changing the way networking and security work together.

  • Our Customers chevron

    Netskope serves more than 3,400 customers worldwide including more than 30 of the Fortune 100

  • Our Partners chevron

    We partner with security leaders to help you secure your journey to the cloud.

A Leader in SSE.
Now a Leader in Single-Vendor SASE.

Learn why Netskope debuted as a leader in the 2024 Gartner® Magic Quadrant™️ for Single-Vendor Secure Access Service Edge

Get the report
Customer Visionary Spotlights

Read how innovative customers are successfully navigating today’s changing networking & security landscape through the Netskope One platform.

Get the eBook
Customer Visionary Spotlights
Netskope’s partner-centric go-to-market strategy enables our partners to maximize their growth and profitability while transforming enterprise security.

Learn about Netskope Partners
Group of diverse young professionals smiling
Your Network of Tomorrow

Plan your path toward a faster, more secure, and more resilient network designed for the applications and users that you support.

Get the white paper
Your Network of Tomorrow
Introducing the Netskope One Platform

Netskope One is a cloud-native platform that offers converged security and networking services to enable your SASE and zero trust transformation.

Learn about Netskope One
Abstract with blue lighting
Embrace a Secure Access Service Edge (SASE) architecture

Netskope NewEdge is the world’s largest, highest-performing security private cloud and provides customers with unparalleled service coverage, performance and resilience.

Learn about NewEdge
NewEdge
Netskope Cloud Exchange

The Netskope Cloud Exchange (CE) provides customers with powerful integration tools to leverage investments across their security posture.

Learn about Cloud Exchange
Netskope video
The platform of the future is Netskope

Intelligent Security Service Edge (SSE), Cloud Access Security Broker (CASB), Cloud Firewall, Next Generation Secure Web Gateway (SWG), and Private Access for ZTNA built natively into a single solution to help every business on its journey to Secure Access Service Edge (SASE) architecture.

Go to Products Overview
Netskope video
Next Gen SASE Branch is hybrid — connected, secured, and automated

Netskope Next Gen SASE Branch converges Context-Aware SASE Fabric, Zero-Trust Hybrid Security, and SkopeAI-powered Cloud Orchestrator into a unified cloud offering, ushering in a fully modernized branch experience for the borderless enterprise.

Learn about Next Gen SASE Branch
People at the open space office
Designing a SASE Architecture For Dummies

Get your complimentary copy of the only guide to SASE design you’ll ever need.

Get the eBook
Make the move to market-leading cloud security services with minimal latency and high reliability.

Learn about NewEdge
Lighted highway through mountainside switchbacks
Safely enable the use of generative AI applications with application access control, real-time user coaching, and best-in-class data protection.

Learn how we secure generative AI use
Safely Enable ChatGPT and Generative AI
Zero trust solutions for SSE and SASE deployments

Learn about Zero Trust
Boat driving through open sea
Netskope achieves FedRAMP High Authorization

Choose Netskope GovCloud to accelerate your agency’s transformation.

Learn about Netskope GovCloud
Netskope GovCloud
  • Resources chevron

    Learn more about how Netskope can help you secure your journey to the cloud.

  • Blog chevron

    Learn how Netskope enables security and networking transformation through security service edge (SSE)

  • Events and Workshops chevron

    Stay ahead of the latest security trends and connect with your peers.

  • Security Defined chevron

    Everything you need to know in our cybersecurity encyclopedia.

Security Visionaries Podcast

The Convergence of CIO & CISO Roles
Join host Max Havey on the latest episode of Security Visionaries as he sits down with guest Jadee Hanson, CISO at Vanta.

Play the podcast
The Convergence of CIO & CISO Roles
Latest Blogs

Read how Netskope can enable the Zero Trust and SASE journey through security service edge (SSE) capabilities.

Read the blog
Sunrise and cloudy sky
SASE Week 2023: Your SASE journey starts now!

Replay sessions from the fourth annual SASE Week.

Explore sessions
SASE Week 2023
What is SASE?

Learn about the future convergence of networking and security tools in today’s cloud dominant business model.

Learn about SASE
  • Company chevron

    We help you stay ahead of cloud, data, and network security challenges.

  • Leadership chevron

    Our leadership team is fiercely committed to doing everything it takes to make our customers successful.

  • Customer Solutions chevron

    We are here for you and with you every step of the way, ensuring your success with Netskope.

  • Training and Certification chevron

    Netskope training will help you become a cloud security expert.

Supporting sustainability through data security

Netskope is proud to participate in Vision 2045: an initiative aimed to raise awareness on private industry’s role in sustainability.

Find out more
Supporting Sustainability Through Data Security
Thinkers, builders, dreamers, innovators. Together, we deliver cutting-edge cloud security solutions to help our customers protect their data and people.

Meet our team
Group of hikers scaling a snowy mountain
Netskope’s talented and experienced Professional Services team provides a prescriptive approach to your successful implementation.

Learn about Professional Services
Netskope Professional Services
Secure your digital transformation journey and make the most of your cloud, web, and private applications with Netskope training.

Learn about Training and Certifications
Group of young professionals working

A Real-World Look at AWS Best Practices: Storage

Aug 24 2021

Introduction

Best practices for securing an AWS environment have been well-documented and generally accepted, such as AWS’s guidance. However, organizations may still find it challenging on how to begin applying this guidance to their specific environments.

  • Which controls should be applied out-of-the-box vs. customized?
  • What pitfalls exist in implementing the various controls or checks?
  • How do you prioritize remediation of the “sea of red” violations?

In this blog series, we’ll analyze anonymized data from Netskope customers that include security settings of 650,000 entities from 1,143 AWS accounts across several hundred organizations. We’ll look at the configuration from the perspective of the best practices, see what’s commonly occurring in the real world, and:

  • Discuss specific risk areas that should be prioritized
  • Identify underlying root causes and potential pitfalls
  • Focus on practical guidance for applying the Benchmark to your specific environment

This blog post focuses on IAM security controls related to bucket storage. Based on the Netskope dataset analyzed, we will highlight two opportunities to improve security:

  1. Remove Public Buckets: Review public S3 buckets and set Block Public Access. Over 58% of buckets do not have Block Public Access set.
  2. Encryption: Encrypt S3 buckets and EBS volumes and enforce HTTPS transfers for S3 bucket access. More than 40% of S3 buckets and EBS volumes are not encrypted at rest, and more than 88% of buckets allow unencrypted access using HTTP.

Storage

Four controls related to storage best practices are:

In our dataset, we looked at configuration settings for 26,228 buckets and 132,912 volumes across 1,143 accounts, with the following findings:

#Best Practice# Violations%
1Ensure that your Amazon S3 buckets are not publicly accessible15,29358.3
2Enforce encryption of data in transit from S3 buckets23,14388.2
3Set server-side data encryption for S3 buckets1,16244.3
4Set server-side data encryption for EBS volumes59,87745.0

1. Public S3 Buckets

Background: Access to data residing on S3 buckets can be complicated since permissions can be specified in different ways with object ACLs, bucket ACLs, bucket policies, and IAM user policies. In some cases, if a bucket is used to serve public content e.g. for a web server, then public access (to anonymous or any authenticated user) is expected. However, in many cases, publicly accessible data is unintended and is a common cause of data loss

AWS provides a setting, “Block Public Access”, which when set, ensures that the bucket is private by ignoring any public ACLs or public policies. Further, it prevents changing of bucket/object ACLs and bucket policies to make it public. Conversely, when it is disabled, then any public ACLs and policies will take effect and authorized users are also able to change the bucket ACLs and policies. Note that it is possible for a bucket to have “Block Public Access” disabled and not actually have any public ACLs or policies — in this case, the bucket is “potentially public.” New buckets have ”Block Public Access” set by default.

Data: 15,293 (58.3%) of the S3 buckets in this dataset do not have “Block Public Access” enabled.

Analysis:

We will look further into the data to answer two questions:

  • Because a bucket has “Block Public Access” disabled, it does not mean the bucket actually has exposed data publicly, but it means the bucket can be potentially configured to be public. What subset of buckets actually have data exposed publicly vs. potentially public?
  • Of those buckets that are public, are any expected to be public (e.g. a web server)?
  1. Public vs Potentially Public Buckets

    To answer the first question, we will break down which of the 15,293 buckets that have “Block Public Access” disabled to see which of those buckets actually have public bucket policies or bucket ACLs. If the bucket has public ACLs or public policies, then it is categorized as “public.” If they do not, then the bucket is categorized as “potentially public.” In evaluating “public,” we follow the AWS definition of “public” as described in: Blocking public access to your Amazon S3 storage.

    DescriptionNotes# Buckets%
    Block Public Access is not set15,293100
    Potentially PublicThese buckets do not have public bucket policies or bucket ACLs.14,71496
    PublicThese buckets have public bucket policies or ACLs5794

    The high majority of the buckets (14,714 out of 15,293 or 96%) are “potentially public,” i.e. do not have “Block Public Access” set and do not yet have any public bucket policies or ACLs. These buckets can easily be made public by users with permissions to change bucket ACLs or policies. These buckets should be reviewed and if they are meant to be private, then the “Block Public Access” should be enabled.

    Essentially, 4% of the 15,293 buckets are at high-risk, while the other 96% are potentially at risk. This would guide prioritization for remediation.

  2. Unexpected vs Expected Public Buckets

    Of the 579 buckets above that are public, some are public because of their purpose, such as being a public web server. The buckets that are not providing web content should be reviewed to see if they should be changed to private. This table breaks down the 579 public buckets into web-servers and non-web servers based:

    DescriptionNotes# Bucket%
    Public Buckets579100
    Web Server (Static WebsiteThese buckets either set CORS headers or respond with http status code 200 to a HTTP GET request of the bucket's static website endpoint.24242
    Non-Web ServerThese buckets have public bucket policies or ACLs33758

    We found that 337 or 58% of the 579 public buckets are not static websites. These buckets should be reviewed to determine whether they need to be public or not, and if not, changed to private by setting the Block Public Access to true.

Controls:

  • Detection/Audit

    Auditing public buckets can be done using several methods:
  • Prevention/Mitigation
    • Public Access Block: The best prevention for unexpected public buckets is to apply the Public Access Block to private buckets, which will ensure that they are not only private but will prevent them from accidentally being changed to public by blocking modification of the bucket policies or ACLs.

      The Console and CLI provide easy ways to set the Public Access Block setting:

      aws s3api put-public-access-block

    • Public Accounts: If possible, isolate public buckets in certain accounts with public resources and set the Public Access Block at the account level and cross-account access as necessary from other AWS accounts. In this way, the accounts become clear administrative and security boundaries and are easier to maintain and track public resources.
    • Tags: Having a standard tagging system will also help in identifying, tracking, and searching for public buckets. When public buckets are provisioned, they are tagged with a well known tag. The tags become easy auditable checks to identify expected vs unexpected public buckets.

2. S3 Encryption-in-transit

Background: Encryption of data transfers to and from S3 buckets helps protect against man-in-the-middle attacks and supports data compliance regulations. Encryption of data transfers occurs if we can force all methods including API/CLI access or web access of the bucket to always use https.

HTTPS data transfers can be enforced by setting a bucket policy with a deny statement if an AWS condition, aws:SecureTransport, is false:

{
  "Id": "ExamplePolicy",
  "Version": "2012-10-17",
  "Statement": [
    {
      "Sid": "AllowSSLRequestsOnly",
      "Action": "s3:*",
      "Effect": "Deny",
      "Resource": [
        "arn:aws:s3:::DOC-EXAMPLE-BUCKET",
        "arn:aws:s3:::DOC-EXAMPLE-BUCKET/*"
      ],
      "Condition": {
        "Bool": {
          "aws:SecureTransport": "false"
        }
      },
      "Principal": "*"
    }
  ]
}

You want to make sure that this is a Deny statement with a match on false, as explained in: What S3 bucket policy should I use to comply with the AWS Config rule s3-bucket-ssl-requests-only?

Data: 23,143 (88%) of the S3 buckets in this dataset do not have encryption-in-transit enabled, which means enforcement of https for data transfer. 

Analysis: The high majority of 88% indicates that this policy is rarely enforced in the buckets in this dataset. Since this policy is easy to implement and otherwise transparent to the user, organizations should immediately enforce encryption of data transfers in order to achieve a higher level of security and compliance.

Controls:

  • Detection/Audit
    • The best way to prevent unencrypted data in transit, is to have regular, automated checks on all bucket policies to ensure that the appropriate SecureTransport condition check exists for each bucket utilizing one of the Detection/Audit methods.
    • Bucket policies can be audited through the CLI:

      aws s3api get-bucket-policy

  • Prevention/Mitigation
    • Bucket policies can be set through the Console or CLI:

      aws s3api put-bucket-policy

3. S3 Encryption-at-rest

Background:

Most compliance/control frameworks specify that default server-side encryption should be enabled for data storage. Encryption of S3 bucket data at rest can help limit unauthorized access and mitigate impact of data loss. There are several server-side encryption approaches available that can be set by default and have different trade-offs in terms of changes required by users/clients, security, and costs:

  1. SSE-S3: Server-Side Encryption with Customer Master Keys (CMKs) provided by and managed by AWS (SSE-S3)
  2. SSE-KMS: Server-Side Encryption with CMKs provided by:
    1. AWS or
    2. Customer
      managed by AWS in the Key Management Service.
  3. SSE-C: Server-Side Encryption with CMKs provided by and managed by Customer

Here are some of the key differences:

MethodMaster Key provided byMaster Key managed byWork involvedCostSecurity Implications
1. SSE-S3AWSAWSLow
- configure bucket encryption
No additional charges- Transparent to authorized bucket users
- Any authorized user has access
- Better for compliance
2a. SSE-KMS

(AWS)
AWSAWSModerate
- configure bucket encryption
- specify AWS CMK id in API calls
Some additional charges e.g. 10K uploads and 2M downloads per month might cost ~$7/mo.- Helps mitigate over-privileged access i.e. if user doesn't have access to key in KMS, can't access
- audit trail of CMK use
2b. SSE-KMS

(Customer)
CustomerAWSModerate
- configure bucket encryption
- provision CMK
- specify customer CMK id in API calls
Some additional charges e.g. 10K uploads and 2M downloads per month might cost ~$7/mo.- Helps mitigate over-privileged access i.e. if user doesn't have access to key in KMS, can't access
- audit trail of CMK use
3. SSE-CCustomerCustomerHigher
- configure bucket encryption
- provision CMK
- pass customer CMK in API calls
- storage/management of CMK
No additional charges- Mitigates over-privileged access with tighter controls on CMK i.e. if user doesn't have the actual CMK, can't access.

Additional details on trade-offs and guidance on setting and enforcing server-side encryption are described in: Changing your Amazon S3 encryption from S3-Managed to AWS KMS

Data: 11,621 (44%) S3 buckets in this dataset do not have any encryption enabled.

Analysis: Almost half of the S3 buckets do not encrypt data at rest. At a minimum, for compliance reasons, AWS-managed server-side encryption should be enabled as it’s free and transparent to users.

Controls:

  • Detection/Audit
    • Bucket policies can be audited through the CLI:

      aws s3api get-bucket-encryption


    • AWS Config can also detect S3 buckets that do not have server-side encryption enabled.
  • Prevention/Mitigation
    • For S3 buckets, you can select one of the two available encryption types in the Console:
      Screenshot of the two available encryption types in the Console
    • Encryption can also be set using the CLI:

      aws s3api put-bucket-encryption --server-side-encryption-configuration '{"Rules":[{"ApplyServerSideEncryptionByDefault":{"SSEAlgorithm":"AES256"}}]}'

      aws s3api put-bucket-encryption --server-side-encryption-configuration '{"Rules":[{"ApplyServerSideEncryptionByDefault":{"SSEAlgorithm":"aws:kms","KMSMasterKeyID": "arn:aws:kms:...:key/<key_id>"}}]}'

4. EBS Volume Encryption-at-rest

Background:

Encryption of EBS volumes helps support compliance controls around data privacy.

Additional best practices for EBS encryption can be found here: Must-know best practices for Amazon EBS encryption

Data: 45% of the EBS volumes in this dataset do not have encryption enabled. For compliance purposes, EBS encryption can be set by default to protect data at rest, with either AWS or customer-managed master keys.

Analysis: Similar to S3 buckets, about 44% of EBS volumes of EC2 instances are unencrypted. EBS volumes can be encrypted by default using AWS or customer-managed keys. Since the AWS encryption is free and easy, customers should at a minimum enable this setting.

Controls:

  • Detection/Audit
    • To prevent unencrypted EBS volumes, a regular and automated check on the default settings can be done, using the detection/mitigation check within a regular scheduled job.
    • The CLI can be used to check the current default EBS encryption settings:

      aws ec2 get-ebs-encryption-by-default
    • AWS Config can also detect when EBS encryption is not enabled by default.
  • Prevention/Mitigation
    • Default EBS encryption can be set using the Console:
      Screenshot of default EBS encryption that can be set using the Console