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Security Defined Cybersecurity Encyclopediaクラウドアクセスセキュリティブローカー(CASB)とは

Cloud Access Security Broker (CASB)

8 min read

What is a CASB?

According to Gartner, a cloud access security broker (CASB) is an on-premises or cloud-based security policy enforcement point that is placed between cloud service consumers and cloud service providers to combine and interject enterprise security policies as cloud-based resources are accessed. Think of the CASB as the sheriff that enforces the laws set by the cloud service administrators.

組織は、クラウドサービスがその境界を越えて直接制御できない場合でも、クラウドサービスのリスクへの対応、セキュリティポリシーの適用、規制の遵守のために、CASB ベンダーに目を向けることがますます増えています。

casb definition


What are the Four Pillars of CASBs?

These are the foundational building blocks of any CASB solution. All pillars are required to have an effective program.

1. Visibility

企業には、マネージドクラウドサービスと非マネージドクラウドサービスの両方について、可視性と制御が必要です。クラウドサービスで「許可」または「ブロック」のスタンスを取るのではなく、クラウドブローカレッジによって、IT部門がサービスへのアクセスとサービス内のアクティビティおよびデータを管理しつつ、有用なサービスに対してOKを出せるようにする必要があります。これは、企業のデバイスのユーザーにはMicrosoft Office 365のような認可済みスイートに対するフルアクセスが提供されるが、管理対象外のデバイスのユーザーにはウェブ専用の電子メールが提供されることを意味しています。また、これは非認可サービスのカテゴリ全体で「社外の共有なし」ポリシーを強制することを意味しています。

While cloud security is the key focus of a cloud access security broker, another value provided is helping you get your arms around cloud spend. A CASB can help you discover all cloud services in use, report on what your cloud spend is, and find redundancies in functionality and license costs. A CASB can produce valuable business and financial information as well as protection.

2. Compliance

Compliance is a major consideration when organizations decide to move their data and systems to the cloud. These compliance standards are meant to ensure the safety of personal and corporate data, and ignoring these concerns can lead to dangerous and costly breaches.

Cloud access security brokers can help ensure compliance in the cloud whether you are a healthcare organization worried about HIPAA or HITECH compliance, a retail company concerned with PCI compliance, or a financial services organization needing to comply with FFIEC and FINRA. A CASB can help safeguard your company against costly data breaches by maintaining the data regulations set by your industry.

3. Data Security


脅威観察に関するより深い調査により、企業は、悪質な活動が発生する前に特定して阻止できます。CASB はそのためのゲートキーパーとして機能ます。ITニーズとビジネスプラクティスの両方に精通したCASBは、今必要なアプローチで組織のセキュリティを強化します。

4. Threat Protection

Organizations need to ensure their employees aren’t introducing or propagating cloud malware and threats through vectors such as cloud storage services and their associated sync clients and services. This means being able to scan and remediate threats across internal and external networks, in real-time when an employee tries to share or upload an infected file. This also means detecting and preventing unauthorized user access to cloud services and data, which can help to identify compromised accounts.

CASB は、クラウドの脅威やマルウェアから組織を保護できます。貴社にとって、優先順位の高い静的マルウェア分析と動的マルウェア分析を組み合わせて、高度な脅威インテリジェンスを実現できることが重要です。一部の脅威は、クラウドサービスから発信され、またはクラウドサービスによってさらに伝播される可能性があるため、防ぐための適切な脅威対策が必要になります。

Resource: CASB Request for Proposal Template
Report: 2020 Gartner Magic Quadrants for SWG and CASB


What are the Top Three Uses for CASBs?

1. Govern Usage

Well-known for efficiency in discovering shadow IT behaviors, CASBs are also savvy across further organization security. A CASB can govern your organization’s cloud usage with granular visibility and control. Rather than take a one-size-fits-all approach by blocking services, CASBs allow you to govern usage based on identity, service, activity, application, and data.

Additionally, you can define policies based on service category or risk and choose from actions such as block, alert, bypass, encrypt, quarantine, and coach for policy enforcement. Finally, you can use these instances to alert your IT team for actions taken against any policy in place for internal monitoring.

2. Secure Data

Protect and prevent the loss of sensitive data across all of the cloud services in your environment, not just the ones you sanction. Take advantage of advanced, enterprise DLP to discover and protect sensitive data in sanctioned cloud services and en route to or from any cloud service, sanctioned or unsanctioned, whether users are on-premises or remote, on a mobile device or accessing from a web browser, or entering from a mobile app or sync client. Combat loss of data with encryption, tokenization, or upload prevention.

3. Protect Against Threats

Guard against cloud-based threats such as malware and ransomware. Start with full visibility of all cloud services, even those using SSL-encrypted connections. Use anomaly detection, and threat intelligence sources such as which of your users has compromised accounts. Then, layer in static and dynamic anti-malware detections, plus machine learning to detect ransomware. Finally, arm the rest of your security infrastructure with your findings through out-of-the-box integrations and workflows. Threats will continue to innovate their approach, so your CASB vendor should too.


The Ten CASB Product Capability Questions You Need to Ask

Your organization is evaluating cloud access security brokers to safely enable sanctioned and unsanctioned cloud services. This list of questions gives you specific, use case-based examples that will help you differentiate the capabilities between the CASB vendors you may be evaluating.

1. Can I control activities in managed and unmanaged cloud applications instead of having to block services altogether?

A: Rather than take a sledgehammer to the service by blocking it, take a scalpel to an activity such as “share”; Do it at a category level – across any cloud storage service, for example. This lets you allow, not block services while mitigating risk.

2. Can I enforce my sensitive data policies in and en route to cloud services? Can I reduce false positives by only looking at cloud transactions that matter?

A: Rather than find and secure content in just your sanctioned service, do it across both sanctioned and unsanctioned services, and for content that’s at rest and en route. Also, minimize false positives and increase accuracy by reducing the surface area through context. Filter out the cloud transactions you care about by removing users, services, categories, locations, and activities from what you inspect and enforce policies.

3. Can I enforce policies based on Microsoft Active Directory groups or organizational units?

A: Rather than upload or enter user data manually, enforce policies that incorporate groups from your enterprise directory such as Microsoft Active Directory.

4. Can I detect cloud activity anomalies like excessive downloads or shares across any service, or if users are sending renamed files or extensions?

A: Rather than detecting anomalies only in sanctioned services or at a coarse-grained level such as access, detect anomalies based on activities across any service, sanctioned or unsanctioned.

5. Can I monitor and report on activity in regulated services, like finance and accounting ones, for compliance purposes?

A: Rather than keep regulated services on-premises, migrate them to the cloud while also complying with regulations such as Sarbanes-Oxley. Report on access and data modifications within cloud-based systems of record.

6. Can I enforce policies remotely, including on mobile and in sync clients?

A: Rather than exclude on-premises monitoring and control from your cloud security model, enforce your policies wherever your users are and whatever their device.

7. Can I mitigate risk against users with compromised accounts?

A: Identify and protect against users accessing your services with compromised account credentials.

8. Can I find and remediate threats and malware in my cloud services?

A: Identify and protect against threats and malware in or en route to or from any cloud service.

9. Do you enhance the value of my existing investments by enabling me to integrate with on-premises solutions such as DLP, SIEM, malware sandbox, and EDR?

A: Rather than deploy cloud security in a silo, make your existing investments more valuable by adding a cloud access security broker.

10. Do you facilitate the deployment options that meet my requirements, including keeping all of my data on-premises? Are you a future-proof investment?

A: Rather than be forced into a CASB vendor’s deployment model, choose the deployment that best fits your requirements, now and in the future.


The Role of CASBs in a SASE Dominated Future

With the recent and massive shifts over to the cloud, CASB technology is morphing into something bigger than itself. Combined with other technologies such as data loss prevention (DLP) and Next Generation Secure Web Gateways, CASB is molding into just one piece of what is known as Secure Access Service Edge (SASE) architecture.

SASE combines multiple security and networking technologies to provide comprehensive web and cloud security without the hiccups of traditional perimeter security, such as latency and lack of context into data usage.

What this means is that a singular focus on CASB is no longer an option for companies. It’ll require a combined approach of multiple tools in which CASBs are just a small sliver of this security strategy.

White Paper: SASE and the Seven Forces Shaping Security Transformation
Blog: CASBとSWGが進む道


Netskope a LEADER in the 2021 IDC MarketScape for Cloud Security Gateways

Netskope is positioned as a Leader in the IDC MarketScape for Cloud Security Gateways in both “Strategies” and “Capabilities”


Netskope’s approach to Cloud Security Gateways (also known as CASB – Cloud Access Security Broker) has been consistently lauded by customers and top technology analysts throughout the world. As a fundamental cloud security service, CASB is critical to SASE architecture and Security Service Edge (SSE) that will dominate modern enterprise security and networking in the years to come.


Learn more about our placement and the fundamental benefits of the Netskope CASB solution today.

IDC Marketscape for Cloud Security Gateways - diagram


Netskope Security Cloud Platform

Netskope Security Cloud Platform



Netskope Data Loss Prevention (DLP)

Netskope Data Loss Prevention (DLP)

2020 CASBのマジック クアドラント

2020 CASBのマジック クアドラント

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