Adding Value to Native Cloud Application Security with CASB

By Paul Ilechko, Senior Security Architect, Cedrus

Many companies are starting to look at the Cloud Access Security Broker (CASB) technology as an extra layer of protection for critical corporate data as more and more business processes move to the cloud.

CASB technologies protect critical corporate data stored within cloud apps and among their preventative and detective controls, a key feature is the ability to encrypt data stored within cloud apps.

At the highest level, the concept is quite simple – data flowing out of the organization is encrypted, as it is stored in the cloud. However, in practice there are nuances in the configuration options that may have impact on how you implement encryption in the cloud.

Most users will start with a discovery phase, which typically involves uploading internet egress logs from firewalls or web proxies to the CASB for examination. This provides a detailed report of all cloud application access, usually sorted by a risk assessment that is specific to the CASB vendor doing the evaluation (all of the major CASB vendors have strong research teams who do the Cloud service risk evaluation for you, so that you don’t have to).

This enables a company to start thinking about the policy needed to protect themselves in the cloud, and also to drive conversations with the business departments using the cloud services, to get an understanding of why they are using them, and if they really need them to get their jobs done. This can drive a lot of useful considerations, such as:

• Is this service safe, or is it putting my business/data at risk?
• If it is creating risk, what should I do about? Can I safely block it, or will it cause an issue with my business users?
• If my business users need this functionality, are there better options out there that achieve the same goals without the risk?

This discovery, assessment and policy definition phase can take some time, possibly weeks or even months, before you are ready to take the next step into a more active CASB implementation. To summarize the ways in which CASB can be integrated into a more active protection scheme:

• CASBs provide API level integration with many of the major SaaS, PaaS and IaaS services, allowing for out-of-band integration that perform functions like retroactive analysis of data stored in the cloud, or near real-time data protection capabilities than can be implemented in either a polling or a callback model.
• CASBs typically provide an in-line proxy model of traffic inspection, where either all, or some subset, of your internet traffic can be proxied in real time, and decisions can be made on whether to allow the access to proceed. This can incorporate various Data Loss Prevention (DLP) policies, can check for malware, and can perform contextual access control based around a variety of factors, such as user identity, location, device, time of day, etc. – as well as sophisticated anomaly and threat protection using data analytics, such as unexpected data volumes, non-typical location access, and so on.
• For users who are leery about using a CASB inline for all traffic, particularly when that traffic is already traversing a complex stack of products (firewall, web proxy, IPS, Advanced Threat Protection...), many CASB vendors also provide a “reverse proxy” model for integration with specific sanctioned applications, allowing for deeper control and analysis that integrates the CASB with the cloud service using SAML redirection at login time.

Policy-based encryption

Many platforms, such as Salesforce with its Salesforce Shield capability, provide the ability to encrypt data. With Shield, for example, this can be at either at the file or field level. However, Shield is configured at the organization level. Most companies that use Salesforce will probably have created multiple Salesforce Orgs. It’s likely that you want to define policy consistently across organizations, and even across multiple applications, such as Salesforce and Office365.

A CASB can provide you with the capability to define policy once and apply it many times. You have the option to use the CASB’s own encryption, or in some cases to make use of the CASB’s ability to use API integration to interact with the platform’s own native tools (e.g., some CASB’s are able to call out to Salesforce Shield to perform selective encryption as required by policy). The CASB can protect your data no matter where in an application it resides: in a document, in a record, or in a communication channel such as Chatter. (The CASB can, of course, provide these capabilities for many applications, we are just using Salesforce here as an example.)

Continuous Data Monitoring

A CASB can provide real-time or near-real time monitoring of data. It can use API’s to retroactively examine data stored in a cloud provider looking for exceptions to policy, threats such as malware, or anomalies such as potential ransomware encryptions. It can act as a proxy, examining data in flight and taking policy based actions at a granular level.

Threat and anomaly recognition

CASB’s typically provide strong capabilities around threat protection and anomaly recognition. Using advanced data science techniques against a “big data” store of knowledge, they can recognize negligent and/or malicious behavior, compromised accounts, entitlement sprawl and the like. The exact same set of analytics and policies can be applied across a range of service providers, rather than forcing you to attempt it on a piecemeal basis.

Cross-cloud activity monitoring

Because a CASB can be used to protect multiple applications, it can provide a detailed audit trail of user and administrative actions that traverse actions across multiple clouds, and which can be extremely useful in incident evaluation and forensic investigations. The CASB acts as a single point of activity collection, which can then be used as a channel into your SIEM.

So, to summarize: while many of the major cloud service providers have added interesting and useful security features to their applications, a CASB can add significant additional benefit by streamlining, enhancing and consolidating your security posture across a wide range of applications.