What is a Cloud Access Security Broker (CASB)?

A CASB (Cloud Access Security Broker) is a tool that helps to protect cloud services. It serves as a security policy enforcement point between cloud service consumers and providers. 

CASBs can be deployed on-premises or in the cloud. They play a vital role in securing your company's network, offering robust capabilities to monitor and manage cloud application usage, ensure compliance, and prevent data breaches. 

Functions of CASBs and their benefits in company networks

Network visibility 

To ensure its protection, you need full visibility and knowledge of your sensitive data and over how it's used. CASBs provide that visibility through their detailed logs on all your cloud transactions. 

For instance, CASBs record every login, upload, or download. These logs also capture app-specific behaviors like external file sharing. This helps you know exactly where data goes when shared.

CASBs allow you to filter through these logs to gain more visibility into enterprise activity. Take shadow IT, for example. Also known as unsanctioned applications, these are classified according to risk. So, your CASB lets you decide what needs blocking. 

Traditional CASBs manually detect and catalog unsanctioned cloud apps. Teams of people scour the internet to evaluate these apps reactively. But more advanced CASBs use a system called Zero-day Shadow IT Discovery. This automated system employs machine learning to evaluate apps on the fly.

Cloud Security Posture Management (CSPM) is another critical component of CASBs. CSPM detects misconfigurations in infrastructure as a service (IaaS) platforms. These platforms often require extensive configurations to function correctly. 

A strong cloud security posture is essential to prevent data leakage. For instance, improper configuration of storage solutions like AWS can make sensitive data publicly accessible. CSPM helps you identify and fix these misconfigurations before they cause problems.

Data security

A good CASB can serve as a vigilant gatekeeper for your cloud services. One of the biggest challenges enterprises face is ensuring that sensitive data doesn't fall into the wrong hands. A CASB helps by enforcing data-centric security policies. 

For example, it can automatically encrypt sensitive information before it's uploaded to the cloud. This means that even if someone gains unauthorized access, they won't be able to read the data without the proper decryption key.

Another way a CASB boosts your data security is through data loss prevention (DLP). Let's say an employee tries to upload confidential files to a personal cloud storage account. The CASB can detect this and block the action, ensuring that your sensitive information stays within approved environments. This helps you prevent leaks and maintain control over your data.

Real-time monitoring is another advantage of using a CASB. It continuously analyzes your cloud activity to detect any anomalies. For instance, if it notices an unusual number of downloads from an account, it can flag this activity for review. 

Such anomalies might indicate a compromised account or an insider threat. By catching these red flags early, you can take swift action to mitigate potential breaches.

By leveraging user and entity behavior analytics (UEBA), a CASB can also help you understand normal vs. abnormal behavior. For example, if a user suddenly starts accessing large volumes of data they don't typically interact with, the CASB can alert you. This allows you to investigate and resolve potential security issues swiftly.

Using a CASB, you can also ensure regulatory compliance. Whether it's GDPR, HIPAA, or any other regulation, a CASB can help you enforce the necessary controls. It continuously audits your cloud environments and provides detailed reports. This not only keeps you compliant but also prepares you for any audits or assessments.

Overall, integrating a CASB into your network security strategy offers multiple layers of protection for your data. You gain increased visibility, real-time threat detection, and robust enforcement of your security policies. It's a comprehensive way to ensure your data remains secure in the cloud.

Threat protection

Often, organizations go months without realizing they’ve been infected. Instead of reacting after the fact, it's best to prevent attacks in real time.

You can classify malware into two types: known and unknown. Known malware is easier to deal with because it's been seen before. Standard anti-malware tools can handle it using predefined signatures. 

However, unknown malware, or zero-day threats, pose a greater risk. These are new and unfamiliar, even to most anti-malware vendors. Because of this, zero-day threats are harder to detect and standard tools often fail to protect against them.

First-generation CASBs typically rely on signature-based protection. This method uses a large catalog to identify and stop malware. But they can only stop threats that have been previously recorded. This means they can't handle new, unknown threats effectively. 

Enter behavior-based protection. Unlike the first-gen methods, behavior-based protection stops malware proactively. It can detect and protect against zero-day threats by analyzing the behavior of potential malware. This makes it much more effective in stopping new kinds of attacks.

Using a data-centric approach also helps. It secures sensitive data without needing to install agents on unmanaged devices. This enables you to protect your data seamlessly, even on devices they don't control.

Compliance

The average enterprise has to deal with a labyrinth of regulations—think GDPR, HIPAA, and even industry-specific ones like PCI-DSS. A CASB helps you navigate these tricky waters seamlessly. 

For instance, it monitors your cloud usage in real-time, flagging any activities that might put you at risk of violating GDPR. If someone in your team inadvertently tries to upload sensitive customer data to an unauthorized cloud service, a CASB steps in to block it. This way, you avoid those hefty fines.

For those in the retail sector dealing with PCI-DSS, a CASB makes life a lot easier. It continuously scans for compliance across all your cloud services that handle credit card transactions. 

Imagine catching a potential issue before it spirals into a full-blown security breach. That's exactly what a CASB does. It keeps an eye on your transactions and data flow, ensuring you meet every compliance checkpoint.

In these ways, a CASB acts as your compliance watchdog, providing real-time alerts and automated policy enforcement. This gives you peace of mind knowing that you are always on the right side of the law, no matter how complex your network becomes.

Methods of CASB deployment

API-based CASB deployments

API-based CASB deployments are ideal for environments with multiple SaaS applications like Google Workspace, Office 365, Salesforce, and Dropbox. They offer seamless integration directly into the SaaS platforms and communicate with them using APIs.

That means you get a deep, granular level of visibility and control over your data. Think about it as having a direct line into the heart of your cloud apps. It's highly effective for monitoring user activity, identifying sensitive data, and enforcing compliance policies.

For instance, with Google Workspace, the CASB can use APIs to delve into Gmail, Google Drive, and Google Calendar. It can identify if someone is sharing sensitive documents publicly or if there's an unusual login from a foreign country. This is crucial for spotting insider threats or compromised accounts.

But it's not just about monitoring. API-based CASBs can enforce security policies in real-time. If you have a financial report in Salesforce, for example, the CASB can automatically classify this document as sensitive and apply policies to ensure it's only accessible to your finance team. If someone outside the team tries to access it, the CASB can block that action and alert you instantly.

What’s even more convenient about API-based solutions is their ability to offer retroactive controls. Say you discover that a sensitive document was shared externally last week. With API integration, the CASB can track back, revoke access, and even delete the shared file. This level of control is hard to achieve with other deployment types.

Another useful feature is shadow IT discovery. Using APIs, the CASB can scan your network to find out which unsanctioned apps are being used. For example, if employees are using unauthorized cloud storage services, the CASB will detect it and flag it for you.

However, it's worth noting that API-based CASBs work within the limits of the SaaS provider's API capabilities. Sometimes, this means waiting for the SaaS provider to enhance their APIs to support new functionalities or data points.

API-based CASBs give you a powerful tool to manage and secure your cloud environment with precision. They integrate deeply, act swiftly, and keep your data safe without you having to play catch-up. This is most convenient for growing company\ies, especially those diving deep into cloud-based tools.

Proxy-based CASB deployments

A proxy-based CASB acts as an intermediary that sits between users and their SaaS applications. This setup inspects all traffic going to and from the cloud, enforcing security policies in real time. It can block user traffic to certain applications or prevent files from being uploaded or downloaded to/from unmanaged devices.

Picture yourself trying to access a cloud app. Your access request first hits the CASB proxy before reaching the cloud service. At this point, the CASB tool has all the details it needs. It can decide to let you through, block your access, or even restrict certain actions you want to perform.

Proxy-based CASB deployment can take two forms: forward proxy and reverse proxy.

In forward proxy mode, the proxy is closer to the user. Your device or network routes the traffic to the proxy. One common method for this is using PAC files. These files direct web requests either to the destination or the proxy. However, PAC files can be bypassed easily. 

Another method involves DNS URL redirects, but modifying DNS entries isn't always feasible, especially if a third-party vendor manages them. The third option is deploying agents on endpoints to reroute traffic via a secure VPN tunnel, but managing these agents can be cumbersome.

Forward proxy setups that use PAC files or agents can't monitor unmanaged devices. However, those using DNS configurations can monitor both managed and unmanaged devices. This method analyzes user-cloud application content to detect malicious activity and data leaks. It also enforces context-based access control, provides visibility into shadow IT, and encrypts field-level data.

Conversely, reverse proxy deployment positions the proxy closer to cloud service providers. It’s more seamless and integrates well with Identity as a Service (IDaaS) platforms, authenticating users and rerouting SaaS traffic back to them. 

Unlike forward proxies, reverse proxies don’t use SSL man-in-the-middle techniques, removing related security concerns. No agents are needed to reroute traffic, either.

Reverse proxies, however, don't offer visibility into shadow IT. But they do control access from both managed and unmanaged devices, encrypt data in transit, monitor user activities for insider threats, and implement real-time DLP measures. They’re particularly effective for unmanaged devices and are harder for users to bypass.

So, whether you opt for forward proxy or reverse proxy depends on your organization's specific needs. A hybrid approach combining API and proxy deployment modes often provides the best balance of flexibility and security.

Agent-based CASB Deployments

Agent-based deployment involves installing software agents on each device that needs to be monitored or protected. These agents act as intermediaries, regulating and controlling access to cloud services based on our predefined security policies.

Let's say your sales team frequently accesses Salesforce from their laptops. By having an agent installed on each laptop, you can ensure that sensitive customer data is encrypted before it gets uploaded to the cloud. The agent can also enforce multi-factor authentication, making sure that only authorized personnel have access to the Salesforce account.

A big benefit with agent-based CASB is the level of granularity it offers. These agents can monitor user activities in real-time, flagging any unusual or unauthorized behavior immediately. 

For example, if someone in the marketing department tries to upload a bulk list of customer emails to a third-party service without permission, the agent can block the upload and send an alert to your security team.

Another use case where agent-based CASB shines is remote work. Many employees use personal devices to access company resources, which can be risky without the right security measures. 

By installing agents on these personal devices, you can extend your corporate security policies outside the confines of your internal network. Whether they’re working from a coffee shop or their home office, your data remains protected.

Moreover, agent-based CASB allows for seamless integration with endpoint protection systems you already have in place. You can synchronize policies across different security layers, creating a more cohesive defense strategy. If an endpoint protection system detects malware on a device, the CASB agent can automatically restrict its access to the cloud until the threat is neutralized.

Sure, there are challenges like ensuring all devices have the agents installed and keeping the software up-to-date, but the control and visibility it offers make it worthwhile. Performance is rarely an issue as most agents are lightweight and won’t noticeably slow down your systems.

In practice, agent-based CASBs add a layer of security that’s both robust and adaptable. They are particularly useful in today’s landscape where cloud services are essential, but so is keeping your data secure.