Interposer Library Privilege Separation for Process Isolation
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Solution Overview
Problem
POSIX-based systems often grant running code full access through the root user, making them vulnerable to security breaches since permissions are frequently omitted, allowing attackers to gain complete system access if a vulnerability is exploited.
Innovation Solution
An interposer library is installed to intercept and analyze process relationships, generating an access map that modifies privileges to implement a least privilege solution, where each process is assigned the minimum permissions necessary to function, thereby preventing unauthorized access and ensuring process isolation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If full root user access is granted to running code for ease of operation, then system accessibility and ease of operation are improved, but system security and vulnerability resistance deteriorate
Solution Approach 1:
The patent segments the root user access by creating multiple privilege levels (root user and ordinary user). Code is divided into two categories: privileged code that requires root access and unprivileged code that runs with limited permissions. This segmentation allows the system to maintain ease of operation for necessary privileged operations while restricting access to prevent security vulnerabilities.
Solution Approach 2:
The patent applies local quality by assigning different permission levels to different code segments based on their specific needs. Instead of granting universal root access, each code module receives the minimum necessary privileges for its function. This localized permission assignment maintains operational efficiency for each component while preventing unnecessary exposure to security risks.
2Object-affected harmful factors
If privilege separation is implemented to improve security, then system security is improved, but system complexity increases
Solution Approach 1:
The patent introduces an interposer library as an intermediary layer between privileged and unprivileged code. This interposer handles privilege transitions, permission checks, and resource access mediation. By centralizing these complex security management functions in a single intermediary component, the overall system complexity is managed more effectively while maintaining strong security boundaries.
Solution Approach 2:
The system implements self-service mechanisms where the interposer library automatically manages privilege transitions and permission validation without requiring manual intervention. The system autonomously handles the complexity of privilege separation by embedding security checks and privilege management logic within the interposer, reducing the operational burden while maintaining security.
3Object-affected harmful factors
If minimum privilege assignment is enforced for each process, then security against breaches is improved, but ease of operation and development deteriorate
Solution Approach 1:
The patent applies preliminary action by pre-configuring the interposer library with knowledge of which resources and operations require elevated privileges. During the development phase, the system performs static analysis to identify privileged operations beforehand, allowing developers to write code assuming standard permissions without constantly worrying about privilege restrictions. The privilege transitions are prepared and managed automatically by the interposer.
Solution Approach 2:
The interposer library serves multiple functions: it acts as a security boundary, a privilege transition manager, a resource access mediator, and a development-time abstraction layer. By making the interposer multi-functional, the system provides a universal interface that simplifies development while enforcing minimum privilege principles, as developers interact with a unified API that handles all privilege-related complexity internally.
Data Source
AI summary
In one implementation, an interposer library is installed on an embedded system or another type of computing system. The system may be configured to host web services or route data packets. A processor, executes processes of the system, and the interposer library intercepts data indicative of relationships of the processes. An access map is generated based on relationships of the processes of the system. The system is modified according to a set of procedures derived from the access map. The set of procedures may be derived by the processor or the access map. The set of procedures may be a minimum privilege solution that minimizes the privilege level of each process to a lowest privilege possible while maintaining the requisite functions of the process.