ISO 27001 Access Control Failure (A.5.15)

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Written By Threat NG Staff

An ISO 27001 Access Control Failure, specifically concerning control A.5.15 (Access control), refers to a breakdown or weakness in the processes and mechanisms designed to ensure that only authorized users, systems, or methods are granted access to information and information processing facilities. This failure allows unauthorized access, modification, or destruction of assets, undermining the core security principles of confidentiality, integrity, and availability.

In a cybersecurity context, an access control failure manifests when:

  • Unauthorized Access is Gained: This is the most direct failure, in which an individual or automated attacker bypasses controls to access sensitive data or systems they are not cleared for. This could be due to weak passwords, a lack of multi-factor authentication, or the exploitation of a misconfigured public-facing system.

  • Excessive Permissions Exist: A failure occurs when an authorized user is granted more access than is necessary for their job function (a violation of the principle of least privilege). If that account is compromised, the blast radius of the attack is significantly larger.

  • Access is Not Properly Revoked: When employees leave an organization or change roles, their previous access rights must be revoked immediately. A failure to do so leaves orphaned accounts open to potential insider threat or external compromise.

  • External Exposure Bypasses Intentional Controls: In the realm of External Attack Surface Management (EASM), an access-control failure often stems from the public exposure of assets intended to be protected. For example, a publicly accessible login page or exposed API endpoint represents a direct compromise of the intended access boundary.

  • Misconfiguration Allows Data Leakage: While configuration management (A.8.9) is a separate control, poor configuration often leads to access control failures. An improperly configured firewall rule, a public-facing cloud storage bucket, or an exposed database port are all configuration issues that directly result in an access control failure by making sensitive assets globally accessible.

This control requires organizations to manage and maintain the integrity of their access control systems to ensure only legitimate interactions with assets are permitted.

ThreatNG directly addresses the risks associated with the ISO 27001 Access Control Failure (A.5.15) by continuously assessing the external attack surface for exposures that could bypass or undermine access controls.

External Discovery and Continuous Monitoring

ThreatNG initiates its process with External Discovery, performing a purely external, unauthenticated scan to build a comprehensive inventory of internet-facing assets. This is crucial because access control failures often originate from unknown or unmonitored assets (Shadow IT). ThreatNG then provides Continuous Monitoring of the external attack surface, digital risk, and security ratings of all organizations, ensuring that any new exposures that could lead to an access control failure are immediately identified.

External Assessment and Security Ratings

ThreatNG’s External Assessment identifies specific issues that directly or indirectly represent an access control failure.

Examples of how ThreatNG highlights A.5.15 failures through its Security Ratings (A–F with A being good and F being bad ) include:

  • Data Leak Susceptibility: This rating is derived from identifying risks such as Cloud Exposure (specifically, exposed open cloud buckets) and Compromised Credentials. An open cloud bucket is a direct access control failure, as data is publicly accessible without authentication.

  • Breach & Ransomware Susceptibility: This rating checks for Exposed Ports and Private IPs on subdomains. Exposed ports such as SSH, RDP, or database ports are potential entry points that, if unprotected, can lead to an access control bypass attempt.

  • Cyber Risk Exposure: This rating includes assessing Cloud Exposure and Compromised Credentials, both of which directly relate to unauthorized access.

  • Non-Human Identity (NHI) Exposure: This critical metric quantifies vulnerability from high-privilege machine identities, such as leaked API keys and service accounts. The discovery of these is a severe access control failure, as these "non-human" credentials can grant wide-ranging system access.

Investigation Modules

ThreatNG's investigation modules perform granular checks to pinpoint the exact nature of the access control failure.

Examples of ThreatNG helping in this area include:

  • Subdomain Intelligence: This module identifies content like Admin Pages and APIs on subdomains. The mere exposure of these management interfaces increases the attack surface for unauthorized access attempts. Furthermore, it checks for Subdomain Takeover Susceptibility , where a "dangling DNS" state could allow an attacker to hijack a subdomain and use it for phishing, thereby deceiving users into granting unauthorized access to their accounts.

  • Sensitive Code Exposure: This module directly addresses access failure by discovering Access Credentials and Security Credentials (e.g., PGP private keys, RSA Private Keys) exposed in public code repositories. These exposed secrets allow attackers to bypass authentication entirely.

  • Search Engine Exploitation: This module helps users investigate their susceptibility to exposure of items such as Privileged Folders, Public Passwords, and User Data via search engines. This exposure represents a catastrophic access-control failure, as search-engine indexing enables broad, unauthenticated discovery of sensitive information.

  • Cloud and SaaS Exposure: The facility identifies Open Exposed Cloud Buckets of AWS, Microsoft Azure, and Google Cloud Platform. This finding directly confirms a misconfigured access control list in cloud storage.

Intelligence Repositories

The platform's Intelligence Repositories (DarCache) provide the raw data necessary to prove an access control failure has occurred or is imminent.

  • Compromised Credentials (DarCache Rupture): This repository is a central source of leaked credentials, confirming that a user's Authentication Information (A.5.17) is already exposed and can be used for unauthorized access.

  • Dark Web (DarCache Dark Web): By tracking organizational mentions, it can provide Threat Intelligence (A.5.7) regarding exposed data or credentials being offered for sale, which directly leads to access control compromises.

Reporting

ThreatNG’s reporting capabilities convert these technical findings into compliance-relevant data. The External GRC Assessment Mappings directly correlate issues such as Compromised Emails and Default Port Scan findings with A.5.15 and other ISO 27001 controls. This allows security leaders to justify immediate remediation efforts to close the access control gap and improve overall compliance posture.

ThreatNG and Complementary Solutions

ThreatNG's external focus generates high-confidence data, making it an ideal source of truth for other security tools, which is critical for Technical Vulnerability Management (A.8.2) and Secure System Architecture (A.8.27).

  • Identity and Access Management (IAM) Solutions: If ThreatNG discovers a large set of Compromised Credentials (e.g., email and password combinations from DarCache Rupture) or finds NHI Email Exposure related to administrative roles (e.g., admin@, system@, security@), this evidence can be immediately fed into the IAM solution. The IAM system can then automatically flag those accounts for a forced password reset, disable them until verified, or require immediate re-enrollment in multi-factor authentication (MFA). This moves from simple detection to automated prevention of unauthorized access.

  • Security Information and Event Management (SIEM) / Security Orchestration, Automation, and Response (SOAR): When ThreatNG identifies an open, unauthorized Remote Access Service port (e.g., RDP, SSH) in its Default Port Scan , this high-priority alert, backed by the Context Engine™ for irrefutable attribution, can trigger a SOAR playbook. This playbook would automatically cross-reference the exposed IP address against the internal configuration management database (CMDB) and initiate a network firewall change request to block the external exposure, thereby re-establishing the network access control boundary.

  • Digital Risk Protection (DRP) Solutions: ThreatNG’s discovery of a Domain Name Permutation - Taken with Mail Record indicates an active threat actor preparing a phishing attack designed to capture user credentials (an A.5.15 access control failure). This specific domain information can be shared with a DRP solution to automatically create and deploy an external phishing blocklist across user browsers and email filters, preemptively defending against the credential harvesting attempt.

Threat NG Staff
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