The rapid adoption of cloud infrastructure has led to a dangerous misconception: that cloud environments are inherently secure. Contrary to this belief, breaches in cloud systems remain both frequent and costly. A 2022 report by StrongDM revealed that public cloud breaches average $6.35 million per incident, significantly higher than hybrid cloud breaches, while misconfigurations in cloud setups incur nearly comparable financial penalties.

On-premise breaches, though often less expensive, can result in prolonged operational downtime and cascading disruptions. These realities underscore the critical need for rigorous security evaluations across both environments.

An overview of environment architecture

The foundational architecture of an IT environment dictates its security priorities and challenges. Below, we dissect the structural elements of on-premise and cloud systems to highlight their unique risk profiles.

On-premise infrastructure

On-premise environments are characterised by localised control, making them a preferred choice for organisations prioritising sovereignty over their data and infrastructure. Key considerations include:

• Control and customisation: Full ownership of hardware and software allows organisations to implement bespoke security configurations tailored to their operational needs. This granular control is particularly advantageous for mitigating environment-specific vulnerabilities.

• Data sensitivity: Industries handling classified or proprietary information, such as defence contractors or government agencies, often opt for on-premise solutions to minimise exposure to external threats. Physical containment of data reduces the attack surface accessible to remote adversaries.

• Regulatory compliance: Sectors like healthcare and finance, governed by stringent regulations (e.g., HIPAA, GDPR), benefit from on-premise setups, which simplify adherence to compliance frameworks through controlled access and audit trails.

Cloud-based infrastructure

Cloud architectures prioritise scalability and accessibility, but these advantages introduce distinct security complexities:

• Scalability risks: While elastic resource allocation enables rapid adaptation to workload demands, improperly managed scaling can lead to misconfigured services or exposed APIs.

• Remote accessibility: Cloud systems permit global access, enabling cybersecurity services teams to conduct assessments from any location. However, this convenience necessitates rigorous audits of externally facing assets to prevent inadvertent exposure.

• Cloud-native security tools: Providers offer built-in tools for attack simulation, allowing organisations to test their environments against real-world threats. These tools are designed to address cloud-specific risks, such as insecure serverless functions or overly permissive IAM roles.

Penetration testing differences: On-premise vs cloud

Although both on-premise and cloud penetration testing are grounded in the core objective of uncovering vulnerabilities, the tactics, scope, and considerations differ significantly.

On-premise penetration testing

Traditional testing targets physical infrastructure such as internal servers, network components, and software applications. The focus lies in evaluating security from within the organisation’s perimeter. In some scenarios, testers may even assess physical entry points or hardware vulnerabilities, something that’s irrelevant in the cloud context.

Key areas of concern include:

• Physical security: Testers may evaluate access controls to data centres or assess resilience against social engineering tactics, such as badge cloning or tailgating.

• Insider threats: Human-centric risks, including negligent or malicious employees, require continuous training and monitoring. Phishing simulations and privilege escalation tests are common in these assessments.

• Legacy system maintenance: Outdated hardware or unpatched software often harbours vulnerabilities. Regular audits and decommissioning protocols are critical to mitigating these risks.

Cloud-based penetration testing

Cloud-focused assessments examine infrastructure hosted on third-party platforms and delivered via service models like SaaS, IaaS, or PaaS. Here, penetration testing targets virtual machines, containers, APIs, databases, and serverless applications, often across dynamic and decentralised systems.

What sets cloud testing apart is its emphasis on:

• Shared responsibility: Security obligations are split between the cloud provider (infrastructure hardening) and the customer (data protection, access controls). Testers must validate configurations across this shared model.

• Multi-tenancy risks: Shared environments heighten the risk of cross-tenant attacks. Assessments focus on isolation mechanisms and adherence to provider-specific testing guidelines to avoid collateral damage.

• Dynamic attack surface: Cloud assets, such as containers, serverless functions, and APIs, require continuous monitoring. Testing often incorporates automated tools to map evolving configurations.

Because cloud security is shaped by external platforms and third-party infrastructure, testing strategies must account for limited visibility and access rights compared to in-house environments.

Where on-premise and cloud strategies converge

Despite their differences, on-premise and cloud testing share several foundational methodologies. Whether assessing legacy systems or modern cloud platforms, cybersecurity services generally categorise testing into three different approaches:

1. Black box testing: The tester has no prior knowledge of the system, simulating a real-world external attack.

2. White box testing: The tester has full access to internal configurations, architecture, and credentials, offering a comprehensive security audit.

3. Grey box testing: Here, testers operate with limited information, simulating an insider threat or a more targeted external attack.

Across both environments, penetration testing typically follows five structured phases:

1. Reconnaissance: Gathering intelligence about the target environment.

2. Identification: Discovering exploitable vulnerabilities.

3. Exploitation: Actively attempting to breach systems using discovered flaws.

4. Post-exploitation: Assessing what actions an attacker could take once inside, such as data exfiltration or lateral movement.

5. Reporting: Compiling findings, evidence, and recommended remediation steps into a comprehensive report for stakeholders.

This phased approach ensures that the testing delivers actionable insights for improving an organisation’s security posture.

Common cloud-specific vulnerabilities

Cloud penetration testing often uncovers issues unique to virtualised and distributed environments. Some common vulnerabilities include:

• API vulnerabilities: Inadequately secured APIs can offer attackers a gateway to manipulate services or extract data.
• Account hijacking: Stolen credentials can give attackers access to sensitive data or allow them to execute unauthorised actions within the environment.
• Serverless exploits: These functions, while cost-effective and scalable, can be manipulated to execute malicious code or overload cloud resources.
• Misconfigured storage: Publicly accessible storage buckets or databases often result from configuration errors, exposing sensitive data to unauthorised users.
• Open ports and services: Poorly defined security groups can leave cloud environments open to attack through unnecessary or exposed services.
• IAM mismanagement: Overly permissive roles and user privileges can provide threat actors with access to critical systems, emphasising the importance of least-privilege access policies.

When to choose cloud penetration testing

Organisations that rely heavily on cloud services, particularly those operating entirely within IaaS, PaaS, or SaaS ecosystems, require testing strategies adapted to these models. Cloud penetration testing provides the agility to uncover risks specific to decentralised environments, such as poorly configured containers or insecure APIs.

Companies in fast-paced industries or undergoing digital transformation initiatives benefit from cloud-focused testing by ensuring continuous security evaluation. It also serves businesses handling sensitive client data, enabling them to demonstrate due diligence in safeguarding digital assets to customers and partners alike.

Conclusion

As cyber threats evolve, so must defence strategies. On-premise and cloud environments each present unique challenges, necessitating distinct penetration testing approaches. By aligning testing methodologies with architectural realities, organisations can fortify their defences, mitigate risks, and maintain stakeholder trust in an increasingly interconnected digital landscape.

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