Securing Cloud Resources: Assessing Internet Exposure for Enhanced Defense and Risk Management

Introduction

Organizations increasingly rely on cloud resources to power their infrastructure and deliver scalable services. However, the internet exposure of these resources introduces security challenges that must be addressed to protect sensitive data and mitigate potential breaches. Assessing the level of internet exposure of cloud resources, such as Virtual Machines (VMs), Storage Accounts, Containers, and Databases, plays a vital role in fortifying defenses and safeguarding against potential breaches.

In this article, we will delve into the significance of assessing internet exposure as a critical aspect of cloud resource security, with a specific focus on how it relates to Attack Path analysis and Security Risk evaluation.

We will explore the advanced capabilities of Microsoft Defender for Cloud, particularly its contextualized cloud security posture management features available through its Defender for Cloud Security Posture Management (CSMP). These capabilities provide organizations with comprehensive insights to identify and address internet exposure risks, allowing for enhanced security risk evaluation and the proactive management of their cloud security posture.

The Importance of Assessing Internet Exposure and recommended mitigations

Analyzing the internet exposure of a resource is crucial for organizations as it helps them identify and assess the risks associated with their digital assets. By understanding which resources are exposed to the internet, security teams can evaluate the likelihood and impact of potential attacks. Here are several key reasons why internet exposure plays a vital role in attack path analysis:

  1. Identification of Vulnerable Entry Points: Analyzing internet exposure helps identify the weak entry points that attackers may exploit. When a resource is directly accessible from the internet, it increases the chances of being targeted. Identifying such entry points allows security teams to prioritize the protection and hardening of those specific assets.
  2. Risk Assessment: Internet-exposed resources pose a higher risk as they are potentially reachable by threat actors globally. Considering internet exposure as a factor in attack path analysis enables organizations to assess the level of risk associated with each resource. This assessment helps allocate resources effectively and implement appropriate security measures based on the severity of the exposure.
  3. Reduction of : Understanding the internet exposure of resources allows organizations to minimize their . By limiting the number of assets accessible from the internet, organizations can decrease potential entry points for attackers and lower the overall risk of successful attacks. This reduction can be achieved through various means, such as implementing firewall rules or network segmentation to restrict access.
  4. Prioritization of Security Measures: Attack path analysis based on internet exposure helps organizations prioritize their security measures. By identifying   resources, security teams can focus their efforts on implementing robust security controls, such as regular patching, strong access controls, intrusion detection systems, and continuous monitoring. This targeted approach ensures that resources with the greatest exposure receive the highest level of protection.
  5. Compliance and Regulatory Requirements: Many industries and sectors have specific compliance and regulatory requirements concerning the security of internet-exposed resources. Understanding the internet exposure of assets enables organizations to ensure compliance with relevant standards and regulations. This includes implementing necessary security controls, conducting regular vulnerability assessments, and maintaining audit logs for internet-facing systems.

In situations where a Cloud Virtual Machine, containerized application, or cloud storage with associated databases needs to be accessible online, it is crucial to take specific actions to minimize the risk of a security breach.

Firstly, it is important to implement strong access controls to restrict unauthorized access. This involves using unique and strong passwords and considering multi-factor for an extra layer of security. Limiting administrative privileges to only those who need them reduces the potential for attacks.

Regularly updating and patching the server's operating system, software, and applications is critical. This ensures that known vulnerabilities are addressed, lowering the risk of exploitation.

Following the security best practices to harden the server's configuration is also necessary. Disabling unnecessary services, ports, and protocols helps minimize the server's . Additionally, employing firewalls and configuring them to allow only essential network traffic provides control and monitoring of incoming and outgoing connections.

Using intrusion detection and prevention systems (IDS/IPS) is highly recommended. These systems monitor network traffic in real-time, allowing for prompt identification and response to suspicious activities or potential attacks.

Enabling comprehensive logging and monitoring solutions is crucial for detecting any unusual or suspicious activities. Regularly reviewing logs and implementing automated alerts helps ensure swift responses to potential security incidents.

If feasible, implementing network segmentation isolates the exposed server, application, or database from the internal network, limiting the movement of attackers in case of a breach and minimizing the overall impact.

Regular vulnerability assessments are recommended to proactively identify and address weaknesses in the configuration. This proactive approach helps mitigate potential risks before they can be exploited.

is vital for protecting data in transit and at rest. Implementing protocols such as SSL/TLS for communication and considering for sensitive data stored on the server or in the database enhances overall security.

Having a robust security monitoring system and an incident response plan in place is crucial for effectively handling security incidents. These measures enable prompt detection and response to security incidents or breaches, minimizing their impact.

For containerized applications, additional measures should be taken. Using trusted sources for container images and regularly updating them with the latest security patches ensures their integrity. Implementing runtime security measures such as access control, resource isolation, and namespace restrictions further enhances container security.

By implementing these measures and recommendations, organizations can significantly reduce the risk of breaches and ensure the security of their cloud resources exposed to the internet.

Attack Path Analysis and Internet Exposed resources

Microsoft Defender for Cloud, a comprehensive cloud security solution, provides organizations with robust capabilities to assess and mitigate security risks in their cloud environments.

One critical functionality of Microsoft Defender for Cloud is its ability to generate attack paths, enabling the identification of potential vulnerabilities and their impact on internet-exposed cloud resources.

Let's explore the attack path types specifically related to internet-exposed resources, focusing on Azure VMs, AWS EC2 instances , as well as Azure and AWS data. By examining these attack path scenarios, we can gain valuable insights into the potential risks associated with internet exposure and implement targeted security measures to protect cloud resources effectively.

  1. Azure VMs:
    • Internet exposed VM has high severity vulnerabilities: This attack path highlights VMs that are directly accessible from the internet and have identified high severity vulnerabilities, indicating an increased risk of exploitation.
    • Internet exposed VM with high severity vulnerabilities and high permission to a subscription: This path identifies VMs exposed to the internet with high severity vulnerabilities and elevated permissions within an Azure subscription, necessitating immediate attention.
    • Internet exposed VM with high severity vulnerabilities and read permission to a data store with sensitive data: This path reveals VMs with internet exposure, critical vulnerabilities, and access to a data store containing sensitive information, highlighting the potential for data breaches.
    • Internet exposed VM with high severity vulnerabilities and read permission to a Key Vault: This path uncovers VMs exposed to the internet, susceptible to high severity vulnerabilities, and possessing read permissions to an Azure Key Vault, which may result in unauthorized access to sensitive cryptographic keys.
  2. AWS EC2 Instances:
    • Internet exposed EC2 instance with high severity vulnerabilities and high permission to an account: This path indicates EC2 instances that have internet exposure, significant vulnerabilities, and elevated permissions within an AWS account, necessitating immediate remediation.
    • Internet exposed EC2 instance with high severity vulnerabilities and read permission to a DB: This path identifies EC2 instances with internet exposure, critical vulnerabilities, and read permissions to a database, highlighting potential risks to data confidentiality and integrity.
    • Internet exposed EC2 instances with high severity vulnerabilities and read permission to an S3 bucket: This path uncovers EC2 instances exposed to the internet, susceptible to high severity vulnerabilities, and having read access to an S3 bucket, indicating potential unauthorized data access.
    • Internet exposed EC2 instance with high severity vulnerabilities and read permission to an S3 bucket with sensitive data: This path reveals EC2 instances with internet exposure, critical vulnerabilities, and read access to an S3 bucket containing sensitive data, emphasizing the need for immediate action to protect data assets.
  3. Azure Data:
    • Internet exposed SQL on VM with a user account allowing code execution and commonly used username: This attack path identifies SQL instances on Azure VMs exposed to the internet, with user accounts susceptible to code execution and commonly used usernames, highlighting the potential for unauthorized access and exploitation.
    • Managed database with excessive internet exposure allowing basic : This path uncovers managed databases with excessive internet exposure and configured for basic authentication, indicating the need for stronger authentication mechanisms to prevent unauthorized access.
    • Internet exposed VM with high severity vulnerabilities and a hosted database installed: This path indicates VMs exposed to the internet with significant vulnerabilities and a hosted database, emphasizing the importance of securing the VM and the associated database.
  4. AWS Data:
    • Internet exposed AWS S3 bucket with sensitive data publicly accessible: This path identifies S3 buckets in AWS that are exposed to the internet and publicly accessible, potentially leading to unauthorized data exposure.
    • Internet exposed SQL on EC2 instance with a user account allowing code execution and commonly used username: This attack path uncovers EC2 instances with internet exposure, SQL instances configured with user accounts vulnerable to code execution and commonly used usernames, emphasizing the need for stronger security configurations.

Here a picture of an Attack Path as it exposes a possible attack route starting from a Virtual Machine with exposure to the internet.

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Identifying Internet-Exposed Resources and Supported Cases

Let's examine the supported cases for identifying internet-exposed resources in each platform:

Azure:

  1. IPAddress -> NetworkInterface -> VM: This case involves an IP address associated with a network interface, which is then connected to a virtual machine. Microsoft Defender for Cloud can detect and analyze this configuration.
  2. IPAddress -> NetworkInterfaceConfiguration -> VMSS: This scenario includes an IP address linked to a network interface configuration, which is subsequently associated with a virtual machine scale set (VMSS). Microsoft Defender for Cloud offers extended coverage for this case, ensuring comprehensive analysis post-migration.
  3. IPAddress -> ApplicationGateway -> NetworkInterface -> VM: In this case, the IP address flows through an Application Gateway, then connects to a network interface, and finally reaches a virtual machine. Microsoft Defender for Cloud considers the effective rules, such as ports and protocols, derived from the network interface. Private IPs are converted to public IPs when passing through the Application Gateway.
  4. IPAddress -> ApplicationGateway -> NetworkInterfaceConfiguration -> VMSS: Like the previous case, the IP address traverses an Application Gateway, reaches a network interface configuration, and eventually connects to a VMSS. Microsoft Defender for Cloud covers this configuration as well.
  5. IPAddress -> LoadBalancer -> NetworkInterface -> VM: Here, the IP address passes through a load balancer, reaches a network interface, and connects to a virtual machine. Microsoft Defender for Cloud detects and analyzes this configuration.
  6. IPAddress -> LoadBalancer -> NetworkInterfaceConfiguration -> VMSS: This case involves the IP address passing through a load balancer, reaching a network interface configuration, and connecting to a VMSS. Microsoft Defender for Cloud provides support for this configuration as well.
  7. IPAddress -> AzureFirewall -> NetworkInterface -> VM: In this scenario, the IP address travels through an Azure Firewall, then reaches a network interface, and eventually connects to a virtual machine. Microsoft Defender for Cloud covers this configuration and performs analysis accordingly.
  8. IPAddress -> AzureFirewall -> NetworkInterfaceConfiguration -> VMSS: Similar to the previous case, the IP address traverses an Azure Firewall, reaches a network interface configuration, and connects to a VMSS. Microsoft Defender for Cloud offers support for this configuration as well.

AWS:

  1. IPAddress -> EC2 NetworkInterface -> EC2 Instance: This case involves an IP address directed to an EC2 NetworkInterface, which is then connected to an EC2 Instance. Microsoft Defender for Cloud detects and analyzes this configuration.
  2. IPAddress -> ElasticLoadBalancer (ALB & NLB) -> ELB NetworkInterface -> EC2 NetworkInterface -> EC2 Instance (East-West!): Here, the IP address is routed through an Elastic Load Balancer (Application Load Balancer or Network Load Balancer), reaches an ELB NetworkInterface, then passes through an EC2 NetworkInterface, and finally connects to an EC2 Instance. Microsoft Defender for Cloud covers this configuration, emphasizing east-west communication within the AWS infrastructure.

GCP:

  1. IPAddress -> GCPLoadBalancer -> NetworkInterface -> ComputeInstance/ ComputeInstanceGroup: In this scenario, the IP address travels through a GCP Load Balancer, reaches a network interface, and eventually connects to a Compute Instance or Compute Instance Group.
  2. IPAddress -> NetworkInterface -> ComputeInstance/ ComputeInstanceGroup: Here, the IP address directly connects to a network interface, which in turn connects to a Compute Instance or Compute Instance Group.

Known False Positives:

It is important to note that in some scenarios involving dual-stack configurations, such as ALB/NLB supporting only IPv4 while the has both IPv4 and IPv6, false positives may occur. Microsoft Defender for Cloud is aware of this known false positive scenario and continues to refine its detection capabilities.

 

This article was originally published by Microsoft's Defender for Cloud Blog. You can find the original article here.