The massive migration to applications delivered in a Software-as-a-Service (SaaS) model has fundamentally changed the way we work. Microsoft 365, Salesforce, Slack, Google Workspace - these tools have become the lifeblood of modern business, allowing collaboration and access to data from anywhere in the world. However, this revolution in productivity has brought with it a huge security challenge. Corporate data that once resided securely inside a company’s data center now freely circulates between employees’ devices and cloud providers’ servers, finding itself completely beyond the reach of traditional network protections such as firewalls.
To make matters worse, employees, in search of the best tools for the job, often start using dozens of other unauthorized SaaS applications on their own and without the IT department’s knowledge. This phenomenon, known as Shadow IT, creates a huge “blind spot” - an area invisible to the security department where sensitive corporate data can be stored and accessed in an uncontrolled manner. In response to this challenge, a new key category of solutions has been born: CASB (Cloud Access Security Broker). It’s a gatekeeper that stands at the crossroads between your users and the cloud to restore much-needed visibility, control and protection.
Shortcuts
- What is CASB (Cloud Access Security Broker) and what problem does it solve in the era of SaaS applications?
- What are the four fundamental pillars of functionality for any CASB solution?
- How does CASB help uncover and manage the “Shadow IT” phenomenon?
- What is the data loss protection (DLP) implemented by CASB?
- What are the main CASB implementation models and how do they differ (API, proxy)?
- How can nFlo help you select, implement and manage your CASB platform?
What is CASB (Cloud Access Security Broker) and what problem does it solve in the era of SaaS applications?
CASB (Cloud Access Security Broker), or Cloud Access Security Broker, is a security platform that acts as a control point and intermediary between users and cloud service providers. Its main task is to extend a company’s security policies beyond the traditional network perimeter and enforce them in SaaS, IaaS and PaaS applications over which the company has no direct control.
CASB addresses the fundamental problem of loss of visibility and control inherent in cloud adoption. When an employee accesses Salesforce from their home computer or shares a file from the company’s OneDrive with an outsider, traditional corporate firewalls and Data Loss Prevention (DLP) systems are blind to this activity. They have no visibility into the traffic going directly between the device and the cloud application.
CASB fills this gap by providing security teams with answers to key questions:
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What cloud applications do my employees use (both authorized and “Shadow IT”)?
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Who is accessing the data in these applications and from what device?
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What sensitive data is stored in the cloud and who has access to it?
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Is there suspicious activity that could indicate account takeover or data leakage?
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What are the four fundamental pillars of functionality for any CASB solution?
The functionality of CASB platforms is typically described by four fundamental pillars, which together form a comprehensive strategy for protecting data and applications in the cloud.
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Visibility (Visibility): This is the starting point. CASB provides detailed insight into what cloud applications are being used in an organization. By analyzing network traffic or firewall/proxy logs, it can identify hundreds or even thousands of SaaS services (including “Shadow IT”), assess their risk level and show who is using them and how intensively.
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Compliance: CASB helps organizations ensure compliance with regulations (e.g., RODO, PCI DSS) and internal policies. It can identify where sensitive data (e.g., personal data, credit card data) is stored in the cloud and whether it is properly secured.
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Data Security (Data Security): This is the heart of CASB functionality. These platforms implement advanced Data Loss Prevention (DLP) mechanisms to prevent leaks of sensitive data. CASB can monitor and control file sharing, block attempts to download sensitive data to private devices, or impose encryption on data stored in the cloud.
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Threat Protection (CASB): CASB protects against a wide range of cloud-specific threats. Using user behavior analysis (UEBA), it can detect anomalies that indicate account takeover (e.g., logging in from two different continents within minutes). It can also scan cloud files for malware.
The Four Pillars of CASB Functionality
| Pillar | Main Task | Example Features |
|---|---|---|
| Visibility | The answer to the question, “What do my employees use?” | Discovery of “Shadow IT,” analysis of traffic to SaaS applications, risk assessment of cloud services. |
| Compliance | Answer to the question, “Is my cloud data compliant with regulations?” | Audit of SaaS application security configuration, identification of sensitive data, compliance reporting. |
| Data Security | Answer to the question, “How do I prevent my data from leaking from the cloud?” | Enforcing DLP policies, sharing control, data encryption, watermark overlay. |
| Threat Protection | Answer to the question, “Are my users’ cloud accounts secure?” | Anomaly detection (UEBA), identification of seized accounts, scanning files for malware, access control. |
How does CASB help uncover and manage the “Shadow IT” phenomenon?
“Shadow IT,” the use of IT applications and services by employees without the official approval and knowledge of the IT department, is one of the biggest sources of risk in modern organizations. An employee who uploads a confidential sales report to a free, unsecured file conversion service creates a huge security gap that the company doesn’t even know about.
CASB is the most effective tool to combat this phenomenon. In “discovery” mode, the CASB platform analyzes logs from existing network infrastructure (firewalls, proxy servers) or network traffic directly. Based on this, it creates a detailed report showing all cloud services to which users connect from the company’s network. Instead of a dozen officially approved applications, IT departments often discover to their dismay that there are several hundred in use.
CASB not only identifies these applications, but also helps assess their risk. Each service discovered is compared against a comprehensive database that evaluates it against hundreds of factors, such as its security certifications, compliance with RODO, data encryption policies or the financial stability of the provider. Based on this, IT can make an informed decision: block access to the riskiest applications, officially approve and secure those that are safe and business-needy, or find a safer alternative for them.
What is the data loss protection (DLP) implemented by CASB?
Data Loss Prevention (DLP) is one of CASB’s most important and valuable features. Traditional corporate DLP systems have been effective at monitoring data inside the corporate network - on workstations, file servers or email. However, they are completely helpless when data leaves this perimeter and enters SaaS applications.
CASB is extending DLP’s operations to the cloud. By integrating with applications such as Microsoft 365, Google Workspace and Box, the CASB platform gains insight into the contents of files stored and shared there. Using advanced inspection engines, it can identify sensitive data in these files, such as PESEL numbers, credit card data, sensitive financial information or intellectual property.
Once sensitive data is identified, CASB can automatically enforce predefined security policies. For example, it can:
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Block the sharing of a file containing personal information outside the organization.
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Display a warning to users when they try to download a large number of customer data files.
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Automatically apply encryption or watermarking to a confidential document.
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Remove the public sharing link for a file that was mistakenly shared with the entire world.
What are the main CASB implementation models and how do they differ (API, proxy)?
There are two main architectural models in which CASB platforms operate. Choosing the right model depends on the needs of the organization and the specifics of the applications being protected.
1. API-based CASB (“out-of-band” mode): In this model, the CASB connects directly to the cloud application via its official API. It does not mediate real-time network traffic. Instead, it “queries” the application at regular intervals for event logs and file metadata, analyzing them for threats and policy violations. This mode is very easy to implement (no network changes are required) and is ideal for scanning data at rest and detecting threats after the fact. Its disadvantage is that it lacks the ability to block activities in real time.
2. proxy-based CASB (“in-line” mode): In this model, all network traffic between the user and the cloud application is routed through a CASB proxy server (in the cloud or locally). This allows for real-time inspection and control. CASB can analyze data “on the fly” and immediately block unauthorized activities, such as an attempt to upload a malware file or download a confidential report to a private device. This model offers the strongest protection, but its implementation is more complex and can introduce minor delays.
Modern CASB platforms most often offer a hybrid approach, combining the advantages of both models (known as multi-mode CASB) to provide comprehensive protection for both data at rest and in motion.
How can nFlo help you select, implement and manage your CASB platform?
At nFlo, we see CASB as a key component of a modern security strategy, essential to regaining control in the distributed world of cloud and remote working. However, we understand that choosing and implementing the right solution is a complex task. Our team of cloud security experts is ready to support organizations every step of the way.
Our services begin with an analytical and consulting phase. As part of our “Discovering Shadow IT” workshop, we use CASB tools to scan a client’s environment and create a detailed report on all SaaS applications in use and their associated risks. Based on this analysis, we help select the CASB platform and deployment model that best fits the client’s business needs, risk profile and existing infrastructure.
We provide end-to-end implementation support, handling the entire technical process - from integrating with an identity provider, to configuring DLP and access control policies, to onboarding users. For companies that want to ensure the highest level of protection without committing their own resources, we offer managed services (Managed Cloud Security). In this model, our 24/7 SOC team monitors alerts from the CASB platform, analyzes potential incidents, responds to threats and adjusts policies on an ongoing basis, ensuring continuous and proactive protection of data in the cloud.
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