The emergence of cloud computing transformed the nature of IT ecosystems and infrastructure in many beneficial ways. From cost savings to flexibility to unparalleled scalability, the cloud’s advantages are well-documented. But it’s important not to overlook the fact that migrating to the cloud introduces many new points where unauthorized hackers can try to enter and launch a cyber-attack.
With many organizations having a growing portfolio of Internet-facing assets, cloud adoption is at least partially responsible for the increasingly important security discipline of external attack surface management. Read on to find out what a cloud attack surface is, the attack vector key threats to cloud security, and five tips to reduce attack surface.
As cloud environments expand across SaaS apps, public-facing web applications, APIs, cloud storage buckets, user devices, and edge devices, security teams need a more complete view of potential entry points. This is where Exposure Management and modern ASM platforms can help organizations continuously identify external-facing assets, prioritize risk, and reduce the number of exposed systems attackers can target.
Cloud computing provides organizations and individuals with the on-demand availability of computing resources via a private or public (Internet) network connection. Instead of having to provision and deploy resources on-premise, the cloud abstracts away those duties and lets you essentially rent out what you need for a fee.
The three main service models in modern cloud computing are:
Software as a Service (SaaS) – Third-party vendors deliver useful applications over the Internet for a subscription fee.
Infrastructure as a Service (IaaS) – Third-party cloud service providers deliver rentable infrastructure in the form of servers, networks, operating systems, and storage to customers vias a network connection.
Platform as a Service (PaaS) – Third-party cloud service providers deliver hardware and software tools as services for development teams interested in building, testing, deploying, and scaling custom applications.
Taking a look at these service models through the lens of an attack surface, a distinct characteristic is how the cloud shifts IT assets/resources from being confined to a secure on-premise perimeter to essentially being externally located assets. A cloud attack surface, therefore, is the total area of cloud-based IT resources that is susceptible to unauthorized entry.
This can include public-facing web applications, APIs, cloud storage buckets, exposed network ports, endpoint devices, Internet of Things systems, and edge devices that connect back into cloud services. The broader and more distributed the environment becomes, the more important it is to maintain a current Asset Inventory that reflects both sanctioned and unsanctioned assets.
The earliest recognizable example of cloud computing’s current service models came from the SaaS application Salesforce. Its founders formed the company in 1999 with the aim of delivering customer relationship management software via the Internet to users. By 2006, Amazon and Google followed suit with their own cloud offerings.
A time lag between the promise of the cloud and organizations willing to migrate workflows there meant that adoption didn’t really take off until the mid-2010s. By the end of the decade, more than 90 percent of organizations were in the cloud in some form. Recent trends such as hybrid workforces and Big Data analytics have only furthered the cloud’s appeal.
Cloud computing unequivocally added to the challenges of keeping malevolent actors from hacking systems and stealing data. Availing of applications, platforms, and infrastructure via network connections entails expanding the digital attack surface or physical attack surface to external-facing systems so that threat actors can probe for weaknesses far more easily than they can probe systems that are kept internal. Here is a brief run-through of some of the biggest threats to cloud security.
Working with the cloud involves a lot of tweaking and changing settings, each of which can potentially be configured in a way that puts the security of information or systems in jeopardy. These misconfigurations can come from simple human error or users lacking a basic understanding of cloud security principles and settings.
Strong configuration management helps reduce these risks by standardizing how teams manage identity and access controls, encryption policies, network ports, cloud permissions, and storage settings. Without consistent controls, a minor configuration gap can expose sensitive data or create new attack vectors that security teams may not discover until after compromise.
You don’t have to look far to unearth real-world examples of cloud misconfiguration threats. The Twitch breach of 2021 that led to hackers accessing 128 gigabytes of data stemmed from a cloud server misconfiguration that left the data exposed to hackers.
If you want users to interact with and use cloud resources, then you need to create and manage cloud user accounts. These user accounts provide a potential route into your systems and resources if threat actors can compromise them and abuse any privileges associated with them. And the risk of such a compromise is pretty substantial.
There are a plethora of ways to compromise a cloud account, including social engineering techniques that prey on psychological flaws, credential stuffing attacks that use stolen passwords from previous breaches to exploit users’ tendencies to reuse the same password for many accounts, and brute force attacks that crack weak passwords using algorithms.
Social Engineering remains especially difficult to defend against because different user types interact with cloud systems in different ways. Administrators, developers, contractors, and business users may each have different levels of access, which makes Zero Trust and zero-trust policies important for limiting what compromised accounts can reach. Security teams should also monitor phishing attempts and social engineering attacks that target privileged cloud users or identity providers.
With resources moving outside the internal corporate/business network, maintaining full visibility over assets and systems is more difficult in the cloud. Given the rapid speed at which users can provision and deploy cloud resources, keeping track of everything is not feasible using the traditional asset management and network visibility tools that perform this role on-premise.
A common issue is users provisioning unsanctioned systems, devices, or applications without the oversight and approval of a central IT department. These so-called shadow IT resources can be left with serious security weaknesses without the organization ever knowing they exist until it’s too late.
Low visibility becomes more complex when organizations have external-facing assets spread across cloud platforms, user devices, endpoint devices, and edge devices. Exposure Management and ASM platforms help security teams maintain a living Asset Inventory, identify unmanaged assets, and understand which systems are most likely to create exploitable entry points.
Behind the complex multi-cloud strategy that many businesses run is an equally complex information-sharing ecosystem powered by application programming interfaces (APIs). These APIs allow different applications to interact with each other and with other back-end cloud resources managed by the service provider.
APIs face similar security threats to other web applications, such as broken authorization/authentication, insecure key generation, excessive data exposure, a lack of rate limiting, and more. Not properly securing these interfaces can provide a way for hackers to get into your environment and exploit the connectivity that APIs facilitate to other resources.
API vulnerabilities can also expose sensitive cloud workflows when authorization, rate limiting, input validation, or authentication controls are weak. Common issues such as SQL injection, software vulnerabilities, and excessive data exposure can turn APIs into high-value entry points for attackers.
With these security threats in mind, let’s move on to five ways that you can reduce your cloud attack surface.
Regularly reviewing your cloud configurations with attack surface monitoring is a useful way to identify and mitigate configuration-based vulnerabilities. Ideally, automation should come into play here with tools that scan cloud resources and identify the most common misconfigurations, including access controls, networking configs, cloud storage, and virtual machines. The need for automation is particularly salient when you consider that 80 percent of organizations said it takes more than 24 hours to perform a manual review of a single cloud application’s infrastructure-as-code configuration. This process should feed directly into vulnerability management workflows so security teams can prioritize unpatched software, exposed cloud storage buckets, risky network ports, and other high-impact findings. When paired with Exposure Management or ASM platforms, configuration reviews become part of a broader attack surface reduction program rather than a one-time checklist.
One of the quickest wins in shrinking your cloud attack surface is hardening user accounts against the possibility of compromise. Adopting multi-factor authentication (MFA) is the best way to ensure that even if threat actors get their hands on a legitimate password, they can’t access the associated account without some other form of evidence.
MFA is also a foundational component of Zero Trust because it helps verify user identity before granting access to sensitive cloud resources. For organizations with multiple user types, strong identity and access controls can reduce the risk that a single compromised credential leads to broader cloud exposure.
The principle of least privilege is a best practice for secure systems design that limits a user or program’s access to only the minimum set of privileges required for it to carry out its function or role. It’s critical to apply this practice across all facets of cloud computing, from configuring APIs to setting the permissions for user accounts. Applying this principle consistently reduces the risks from errors or compromises cascading into the abuse of privileges and the eventual access to sensitive data or takedown of critical systems. Least privilege should also extend to service accounts, user devices, endpoint devices, encryption policies, and administrative permissions. This ensures users and systems only have the access required for their role, reducing the blast radius if an account, device, or workload is compromised.
Modern attack surface reduction requires a defense-in-depth approach to prevent the possible spread of malware or other forms of cyber-attack. Defense-in-depth means using many layers of security throughout a system. Network segmentation is an important part of cloud attack surface reduction that controls the traffic that moves between cloud resources, the internet, and on-premise. Stateful firewalls, often available as a service, can prove valuable in scaling network segmentation to the cloud, reducing the attack surface by accounting for the state and context of connections. Segmentation is especially important when cloud environments connect to edge devices, remote locations, operational systems, or hybrid infrastructure. By controlling exposed network ports and limiting lateral movement, organizations can reduce the impact of ransomware attacks, malware risks, and activity from sophisticated nation-state threat actors.
It might sound simple, but simply reducing the number of resources that are accessible via public Internet connections is another effective way to shrink your cloud attack surface. Leading public cloud providers have options for virtual private networks that enable remote workforces to securely access resources over a private connection. Any cloud-stored data should have its access controlled rather than being accessible to anyone with the correct URL. Of course, reducing publicly available resources does require full visibility into your cloud environments.
Security teams should regularly review external-facing assets such as public-facing web applications, APIs, exposed cloud storage buckets, and edge devices to determine whether they truly need public access. Reducing unnecessary exposure limits available attack vectors and supports broader attack surface reduction efforts.
Endpoint controls are not a replacement for cloud attack surface management, but they can reduce risk where user devices, endpoint devices, and edge devices connect to cloud resources. Tools such as Microsoft Defender Antivirus, Microsoft Defender for Endpoint, Endpoint Detection and Response, and Group Policy can help security teams detect malware risks, enforce endpoint controls, and apply ASR rules that limit common attacker behaviors.
ASR rules can help reduce exposure from suspicious scripts, credential theft techniques, Office-based attacks, and other activity that often follows phishing attempts or social engineering attacks. When combined with ASM platforms and Exposure Management, endpoint controls give security teams better context into how cloud assets, user activity, and device-level risks contribute to the overall attack surface.
A good External Attack Surface Management tool with attack surface analysis should have the ability to include cloud in-scope, because the last thing we all need is another siloed solution. It’s a best practice to combine all EASM under one tool.
To help manage your cloud attack surface effectively, you can integrate with AWS, Azure and GCP to scan and monitor public facing assets. You can see changes and vulnerabilities in your cloud attack surface complete with a full description, evidence and remediation advice to speed up remediation efforts.
For organizations building a broader Cyber Resilience strategy, cloud attack surface reduction should work alongside vulnerability management, identity controls, encryption policies, a backup strategy, and compliance programs such as ISO 27001. Bugcrowd helps teams identify and validate the exposures most likely to be exploited, giving security teams the evidence they need to prioritize remediation.
Strong access controls, such as multi-factor authentication, role-based access control (RBAC), and least privilege principles, ensure that only authorized users can access your cloud resources which reduces potential vulnerability or attack vector options. By limiting access to trusted individuals and reducing unnecessary privileges, you minimize the potential attack surface for potential intruders.
Regularly updating and patching your systems in the cloud involves applying the latest cybersecurity patches and updates provided by your cloud service provider for effective attack surface management. This helps address known vulnerabilities and protect against emerging threats, ensuring that your cloud infrastructure and software are equipped with the latest security measures.
Network segmentation involves dividing your cloud environment into separate segments or virtual networks, each with its own security controls and access rules. By isolating different components and services, you limit the lateral movement of attackers or a threat actor, making it harder for them to compromise your entire infrastructure in case of a breach.
Hardening your configurations in the cloud means implementing security best practices and following recommended guidelines for setting up your cloud services, applications, and infrastructure. This includes disabling unnecessary features, using strong encryption, enforcing secure communication protocols, and configuring proper logging and monitoring, among other measures.
ASR rules, or attack surface reduction rules, are endpoint security controls that help block common attacker behaviors such as credential theft, malicious scripts, suspicious Office activity, and abuse of trusted applications. While ASR rules are often associated with Microsoft Defender Antivirus and Microsoft Defender for Endpoint, they also support broader cloud attack surface reduction by limiting how compromised user devices or endpoint devices can be used to reach cloud resources.
Edge devices can expand the cloud attack surface when they connect remote sites, operational systems, sensors, or Internet of Things devices to cloud services. If these systems are misconfigured, unmanaged, or running unpatched software, they can become exposed entry points. Security teams should include edge devices in their Asset Inventory and monitor them alongside other external-facing assets.
ASM platforms support Exposure Management by continuously discovering external-facing assets, identifying software vulnerabilities, detecting misconfigurations, and helping security teams prioritize remediation. This gives organizations a more accurate view of their attack surface across cloud services, public-facing web applications, APIs, endpoint devices, and edge devices.
Encryption policies help protect sensitive data if a cloud asset, user account, or storage resource is exposed. Strong encryption policies should apply to cloud storage buckets, data in transit, data at rest, and systems that connect to cloud environments. They do not eliminate the need for access controls or vulnerability management, but they reduce the potential impact of unauthorized access.
Zero Trust reduces cloud attack surface risk by requiring users, devices, and workloads to verify identity and access before reaching sensitive resources. Zero-trust policies can limit access by role, device health, location, and risk level, which helps reduce exposure if credentials are stolen through phishing attempts, social engineering attacks, or other attack vectors.
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