Cloud Access Security Broker (CASB)

What is a Cloud Access Security Broker (CASB)?

A Cloud Access Security Broker (CASB) is a security solution designed for businesses utilising cloud services. It ensures the protection of applications—whether software-as-a-service (SaaS), infrastructure-as-a-service (IaaS), or platform-as-a-service (PaaS)—against cyber threats and data breaches. By acting as a central point of control, CASBs provide a unified layer of security that simplifies how organizations manage cloud risks. Most CASBs are delivered as cloud-hosted solutions, though on-premises options are available for businesses seeking direct control over their security.

CASBs are effective due to their ability to combine various security technologies into a seamless solution, including tools like shadow IT discovery, access control, and data loss prevention (DLP).

Functioning as a comprehensive security suite, CASBs offer multiple layers of protection. By bundling these features, they enable organizations to proactively address potential cloud vulnerabilities.

The Four Pillars of CASB

Understanding the key components of a CASB is essential for achieving effective cloud security. CASBs offer various functionalities that protect sensitive data and ensure compliance within cloud environments. Here is a list of the critical components that enable CASBs to secure cloud applications:

1. Visibility
Organizations need to monitor user activities across all their cloud applications, including both approved and unapproved services, often referred to as shadow IT. When cloud-based activities occur outside IT's oversight, significant security risks arise, as this data may not comply with organizational protocols. CASBs play a crucial role in detecting high-risk activities that IT teams might overlook.

By providing comprehensive visibility into cloud application usage, including device and location details, CASBs enable businesses to safeguard critical data, intellectual property, and users. Through cloud discovery analysis, enterprises can evaluate the risks associated with various cloud services and determine access permissions. This level of control allows organizations to implement tailored access policies based on users’ roles, locations, and devices, ensuring better management of their cloud environments.

2. Compliance
With the growing use of multiple cloud vendors, organizations face the challenge of maintaining compliance with regulatory standards, regardless of whether they manage their data in-house or through third-party providers. CASBs help businesses address regulatory requirements, including HIPAA, ISO 27001, PCI DSS, and others.

CASBs also assess compliance risks by identifying vulnerable areas within an organization's cloud infrastructure. They provide IT and security teams with insights on where to focus their efforts to ensure that all necessary privacy and security regulations are met.

3. Data Security
As organizations migrate more data to the cloud, protecting sensitive information becomes increasingly critical. While on-premises Data Loss Prevention solutions effectively secure data within internal systems, they don’t extend that protection to the cloud.

Integrating CASBs with existing DLP tools gives businesses visibility into sensitive data as it moves between on-premises systems and the cloud. This integration allows them to track access to sensitive information and apply robust security measures, including access controls, encryption, collaboration control, and tokenization. These capabilities help prevent unauthorized access and data loss, ensuring that business-critical information remains secure, no matter where it is stored or accessed.

4. Threat Detection
Organizations are more vulnerable to cyber threats such as stolen credentials, insider attacks, and external hackers. CASBs enable businesses to detect and respond to unusual or suspicious activities, even when they originate from authorized users.

By establishing a baseline of normal behavior through machine-learning algorithms, CASBs can quickly identify and flag any deviations that indicate potential security threats. Additionally, CASBs deploy tools like adaptive access control, malware detection, and threat intelligence to block and prevent malicious activities, safeguarding the organization from both external and internal threats.

Why CASB is Important?

While cloud computing offers the advantage of anywhere-access, it also opens the door to cybercriminals and digital threats. As businesses move to cloud-based models, securing their data, applications, and services in this environment becomes crucial. Traditional security approaches, designed for on-premises systems, are often inadequate in addressing the complexities of cloud environments.

A key challenge in cloud security is the "shared responsibility model," where cloud service providers (CSPs) secure the underlying infrastructure, while users are responsible for securing everything from the operating system to applications and data. This can create a false sense of security, leading businesses to believe their cloud workloads are fully secured. However, without the right security measures, applications and data remain vulnerable to attacks, including zero-day exploits.

This is where CASBs become essential as they bridge the security gaps by providing visibility, access control, data protection, and threat detection. They also enable businesses to safeguard their cloud environments by enforcing policies that protect sensitive data, prevent unauthorized access, and ensure compliance with industry regulations. In short, CASBs equip businesses to tackle the unique security challenges of the cloud, safeguarding critical assets from both external attacks and internal misconfigurations.

What Role Does a CASB Play in Cloud Security?

CASB strengthens cloud security by offering key features that protect data, manage access, and detect risks.

• Govern Usage
  Granular visibility and control over cloud usage enable organizations to manage access based on identity, activity, and data. Instead of a one-size-fits-all approach, policies can be defined based on risk or service category, allowing actions like blocking, alerting, encrypting, or quarantining data. This ensures secure cloud usage while keeping the IT team informed about policy enforcement.
• Secure Data
  Sensitive data is protected across both sanctioned and unsanctioned cloud services. With enterprise-level data loss prevention tools, sensitive information is secured whether it’s moving between cloud services or accessed from different devices. Encryption, tokenization, and upload prevention methods keep critical data safe, regardless of where it's accessed.
• Protect Against Threats
  Full visibility into cloud services, including those using encrypted connections, helps guard against malware and ransomware. With features like anomaly detection, threat intelligence, and machine learning, risks such as compromised accounts or ransomware are quickly identified and neutralized. Integrations with existing security systems further enhance the organization’s defence strategy, keeping it ahead of evolving threats.

How Does a CASB Work?

CASBs use two main modes to secure cloud services: proxy and API. In proxy mode, they act as intermediaries between users and cloud providers. This involves two types of proxies: forward and reverse. Forward proxies route all traffic from managed devices, ensuring full control, while reverse proxies offer security for unmanaged devices, such as those in “Bring Your Own Key” (BYOK) setups, without requiring device configurations.

In API mode, CASBs directly integrate with SaaS applications for policy enforcement, log monitoring, and data inspection at rest. This approach is efficient for managing unmanaged devices, although API limitations can restrict coverage.

Deployment options include on-premises, cloud-only, or hybrid setups, each offering different levels of control and compliance for sensitive data protection.

However, cloud-only CASBs can introduce potential challenges related to the delegation of responsibility and third-party trust, particularly with the "Bring Your Own Key" (BYOK) model. Relying on CASB providers for encryption key management may conflict with internal or external compliance policies. Additionally, cloud service providers (CSPs) may require whitelisting of CASB IP addresses, which introduces further security concerns. In contrast, on-premises solutions typically offer greater control, especially for organizations focused on data sovereignty and privacy regulations.