Anti-tamper Access Token Modification for Key Resource Protection

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Solution Overview

Problem

Current computer devices face challenges in preventing user processes, even with high privilege levels, from accidentally or maliciously tampering with key resources, leading to errors or security breaches.

Innovation Solution

An anti-tamper mechanism is implemented using an access control list to create a protection group and revise user process access tokens, adding a deny access control entry to restrict access to key resources, ensuring that user processes cannot tamper with security applications regardless of their privilege level.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If user processes are granted high privilege levels such as local administrator level, then application programs can install and operate correctly, but user processes may accidentally or maliciously tamper with key resources leading to errors or security breaches

Engineering Contradiction:
Improveapplication installation and operation capabilityVSAvoidtampering with key resources
Core Design Contradiction:
Adaptability or versatilityVSObject-affected harmful factors

Solution Approach 1:

The patent segments the access control mechanism by creating a specialized protection group (e.g., 'AntiTamper\ProtectGroup') that is distinct from standard privilege groups. This segmentation allows the system to grant high privilege levels for application operation while simultaneously creating a separate access control layer that specifically restricts access to key resources. The access control list is divided into regular entries and deny access control entries, with the latter specifically targeting the protection group to prevent tampering with security application resources.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent introduces an intermediary mechanism in the form of an anti-tamper mechanism that acts as a mediator between user processes and key resources. This intermediary intercepts user processes and dynamically modifies their access tokens to include membership in the protection group. The modified access token serves as an intermediary credential that allows legitimate application operation while automatically enforcing restrictions when accessing key resources, thus mediating between the need for high privileges and the need to prevent tampering.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Reliability

If access control lists are used to restrict access to key resources, then security is improved, but access token complexity increases requiring dynamic modification

Engineering Contradiction:
Improvesecurity against tamperingVSAvoidaccess token management
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent applies preliminary action by pre-configuring the access control list with deny access control entries that specify the protection group before user processes attempt to access key resources. The protection group is created in advance and the corresponding deny entries are established beforehand. When user processes are intercepted, the anti-tamper mechanism dynamically adds the protection group membership to their access tokens, but the restrictive rules are already in place, ensuring security is enforced without requiring complex real-time decision-making during resource access.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The patent introduces dynamics by making access tokens modifiable at runtime. Instead of using static access tokens, the system dynamically modifies user process access tokens to include membership in the protection group. This dynamic modification allows the system to adapt access rights based on the specific process being executed, enabling high-level privileges for legitimate operations while automatically applying restrictions when the protected resource is accessed. The access control system transitions from a static configuration to a dynamic, process-aware security model.

Inventive Principle:
Principle #15Dynamics

Data Source

PatentEP2748755B1Computer device with Anti-tamper resource security
Publication Date: 2016.07.13 AVECTO
  • EP2748755B1 patent drawingFigure 1~2
  • EP2748755B1 patent drawingFigure 3~4
  • EP2748755B1 patent drawingFigure 5

AI summary

A computer device (200) provides an execution environment (203) that supports a plurality of processes (110, 120). A plurality of key resources (115) are associated with a security application (110) that may perform process elevation to grant privileged access rights to a user process (120). A security module (210) is arranged to control access to the key resources (115) using an access control list. An anti-tamper mechanism (240) creates a protection group (117) as a local security group and adds a deny access control entry (116a) to the access control list (116). The anti-tamper mechanism (240) intercepts the user process (120) and creates a revised access token (122b) identifying the user process (120) as a member of the protection group (117). The security module (210) matches the protection group (117) in the revised access token 122b of the user process (120) against the deny access control entry 1 16a in the access control list (116) of the key resources (115) thereby restricting access by the user process (120) even though the user process otherwise has privileges which would allow access to those resources (115).