Main takeaways from this article:
Public cloud security protects multi-tenant environments through a shared responsibility model between providers and customers.
Key risks like misconfigurations, insecure APIs, and insider threats can expose sensitive data if unaddressed.
Best practices for public cloud security include access controls, encryption, API security, and leveraging tools like CSPM and CNAPP.
What is public cloud security?
Public cloud security is about protecting shared cloud environments that many organizations depend on. It’s a shared effort: cloud service providers (CSPs) like AWS, Google Cloud and Azure secure the underlying infrastructure, while users are responsible for safeguarding their data, configurations, and applications. This shared responsibility model works best when both sides do their part, working together to address vulnerabilities and strengthen defenses.
Unlike private clouds, which are single-tenant and exclusive, or hybrid clouds, which combine public and private setups, public clouds offer scalable, on-demand resources—think apps, virtual machines, and storage. These services typically fall into three categories:
Infrastructure as a Service (IaaS): Rent scalable cloud computing and storage resources without the headache of managing physical servers.
Platform as a Service (PaaS): Access platforms and tools to streamline your software development process.
Software as a Service (SaaS): Use web-based apps, like productivity or communication tools, right from your browser.
Public clouds are cost-effective, flexible, and globally accessible, but staying proactive about security is essential to protect sensitive data and meet compliance standards.
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Securing the public cloud environment: who is responsible?
Keeping a public cloud secure relies on clearly defined roles between providers and users.
Public cloud providers
CSPs like AWS, Google Cloud, and Azure handle the backbone of security—data centers, servers, and network infrastructure. They also provide essential tools such as identity and access management (IAM), encryption, firewalls, and logging features. These built-in protections lay a solid foundation but don’t cover everything.
Customers
The rest is up to you. You’re responsible for managing access, configuring security settings, and monitoring activity within your environment. To go beyond the basics, you can add measures like advanced encryption, intrusion detection systems (IDS), and continuous monitoring to address unique risks.
Public cloud security succeeds when providers and customers work together. By playing your part and leveraging the tools available, you can build a resilient environment ready to face today’s evolving threats.
Public cloud security standards
Security standards and compliance frameworks provide a roadmap for securing public cloud environments. They help organizations meet regulatory requirements while strengthening their defenses. Here are the key ones to know:
ISO 27001: This international standard defines how to establish an information security management system (ISMS). Think of it as your guide for identifying risks, implementing cloud security policies, and driving continuous improvements. Following ISO 27001 helps protect sensitive data and adapt to evolving security challenges.
SOC 2 (System and Organization Controls): SOC 2 compliance signals that an organization adheres to five trust principles: security, availability, processing integrity, confidentiality, and privacy. It assures customers that their data is handled securely and responsibly—no surprises, no shortcuts.
NIST (National Institute of Standards and Technology) Framework: The NIST framework, particularly SP 800-53, offers practical guidance for securing public clouds. Covering everything from access controls to incident response, it helps organizations stay ahead of risks with a proactive, rather than reactive, security strategy.
Adopting these standards boosts confidence, minimizes risks, and makes compliance a seamless part of your cloud security journey.
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Public vs. hybrid vs. private cloud security
Public cloud: Public cloud security focuses on protecting data and applications within shared, multi-tenant environments managed by third-party providers like AWS, Google Cloud, and Azure.
Private cloud: Private cloud security involves safeguarding data and applications in a dedicated, single-tenant environment, providing greater control and customization for organizations with strict compliance needs.
Hybrid cloud: Hybrid cloud security addresses the unique challenges of securing data and applications across integrated public and private cloud environments, ensuring safe and seamless data flow between both.
| Features | Public Cloud | Private Cloud | New Column 1 |
|---|---|---|---|
| Ownership | CSP | Enterprise | Enterprise |
| Access | Everyone | Very few | Some |
| Costs | Low to medium | High | Medium to high |
| Customization and control | Lowest control | Highest control | Moderate control |
| Compliance | Weak to medium | Strong | Medium to strong |
| Data sovereignty and localization | Difficult | Easy | Moderately difficult |
| Ease of management | Easy | Difficult | Average |
| Performance | Low to medium | Very high | High |
| Resource sharing | Shared | Not shared | Partially Shared |
| Security | Low to medium | High | Medium to high |
| Sustainability | Low | High | Medium |
Public cloud security risks
Public cloud security can be a complex space to navigate. Understanding the threat landscape is the first step to securing your public cloud. Below are some of the most pressing public cloud security risks that businesses are likely to face.
Misconfigurations: Incorrect security settings in public cloud resources can result in a multitude of high-risk vulnerabilities. Misconfigurations include suboptimal IAM controls, unpatched applications, exposed resources, and weak default settings. Neglected misconfigurations can lead to the exposure and exfiltration of sensitive data.
Lack of visibility and control: The constant commissioning of public cloud resources, both official and unofficial, in agile development environments means that enterprise cloud infrastructures can become overwhelmingly complex. This makes visibility and governance a challenge because enterprises might struggle to get a unified and comprehensive view of their public cloud resources.
Multi-tenancy: Most SaaS and PaaS applications are multi-tenant, which means that they are susceptible to cross-tenant vulnerabilities like ExtraReplica and Hell’s Keychain. Poor security boundaries in cross-tenant applications can result in more lateral damage during security breaches. Tenant isolation is a viable solution, but there is a noticeable lack of standardized tenant isolation frameworks, tools, and best practices.
Access management: The proliferation of public cloud resources introduces numerous security challenges related to access. Enterprises need to have complete control over which digital identities have access to what resources. Any deviation from zero-trust principles can lead to data breaches, account takeovers, and malware injections.
Shadow IT: Public cloud resources are simple and affordable to purchase and activate. This means that employees are increasingly commissioning public cloud resources without IT approval, typically to sidestep complex authorization processes, self-optimize performance, and solve problems quickly. IT resources that are unofficially commissioned are called shadow IT and are difficult to discover, manage, and secure.
Insecure interfaces and APIs: APIs are the secret behind the seamless integration of disparate public cloud applications. While APIs can significantly accelerate digital environments, they are also responsible for an increase in an enterprise’s attack surface. (Misconfigurations in APIs are a common vulnerability exploited by threat actors to breach defenses.)
Insider threats and unauthorized access: Public cloud security risks are often exacerbated by insider threats. Malicious insiders can take advantage of existing cloud vulnerabilities to access crown jewel assets. Negligent insiders are just as damaging because they can unknowingly widen the attack surface.
Advanced persistent threats (APTs): An APT is a type of advanced attack where threat actors breach cloud environments and remain there for long periods to exfiltrate data and cause lateral damage. APT attacks are complex and typically are carried out by experienced and organized cyber criminals.
Distributed denial-of-service (DDoS) attacks: Most CSPs do offer some kind of protection against DDoS attacks. However, the more advanced DDoS attacks can easily bypass default security settings. It’s important to remember that defending public cloud infrastructures from DDoS attacks is not a top priority for CSPs and that there’s little to no DDoS-centric coverage in service-level agreements (SLAs).
9 best practices for public cloud security
Ensuring public cloud security depends on strict adherence to security best practices. Let's take a look at the top public cloud security best practices.
1. Understand the shared responsibility model
The shared responsibility model clearly delineates public cloud security responsibilities and helps you understand which areas of cloud security your CSP will cover, which areas you will take care of, and where there needs to be a collaborative effort. Public cloud responsibilities include:
IAM
Data accountability
Network controls
Endpoint protection
2. Use adaptive multi-factor authentication (MFA)
Make sure that every user has to provide multiple sets of credentials to access critical resources. (This is especially important for companies that have remote or distributed workforces.)
Adaptive MFA takes MFA to the next level by using contextual information and risk analysis to determine the level of authentication required for a specific login attempt. The authentication process is adapted based on threat intelligence, user behavior, and environmental factors (network, location, and device characteristics).
3. Secure APIs and endpoints
Your APIs can be highly susceptible to bugs and vulnerabilities that can be exploited by threat actors to gain access to your system. Ensure protection by encrypting APIs, implementing role-based access controls (RBAC), and establishing rate limits.
4. Encrypt data in motion and at rest
Data breaches are almost an inevitable part of modern IT. However, not all data breaches have to be damaging. Encrypt your data so that no illegitimate user can read or leverage sensitive information even if they manage to access it.
5. Update and patch regularly
Harden your security posture by patching out-of-date software regularly. Your ideal patch management lifecycle should include the following steps: First, develop your inventory. Second, identify, prioritize, test, deploy, and document the patching process.
6. Implement network security protocols
Network security protocols can keep threat actors and illegitimate users from accessing or reading ported data. Examples of network security protocols include hypertext transfer protocol secure (HTTPS) and secure sockets layer (SSL).
7. Leverage platforms like CNAPP and CSPM
The right cloud native application protection platform (CNAPP) solution can help you consolidate your cloud security stack and fortify your public cloud environments in a unified, affordable, and efficient manner.
The most effective CNAPP solutions don’t just identify and remediate public cloud vulnerabilities; they meticulously prioritize them to make sure that non-critical vulnerabilities don’t take up your valuable time and resources.
8. Closely monitor cloud resources and respond to security events
You must constantly monitor and scan cloud resources to make sure vulnerabilities don’t go unnoticed. Most importantly, ensure that high-risk and critical vulnerabilities are remediated in real time. The longer a vulnerability lingers in your public cloud, the higher the chance that a data breach will occur—or has already occurred.
9. Secure the software development lifecycle (SDLC)
Shift left to empower your DevOps engineers and integrate vulnerability management early in your SDLCs. Doing so will help to tackle security vulnerabilities and risks right away and help to reduce the possibilities of large-scale security incidents and data breaches.
Wiz: the best way to approach public cloud security
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