Memory Colour Tagging for Fine-Grained Execution Protection
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Solution Overview
Problem
Existing CPU-based products, including security products like smartcards, face attacks such as buffer overflow, stack overflow, Java Program Counter (JPC), and Java Stack Pointer (JSP) attacks, which current counter measures like software bound checking and canary or double stack protection fail to address effectively without performance penalties.
Innovation Solution
An execution system with a central processing unit, system memory, and a secure agent component that includes a colour memory created during compilation, associating colour tags with memory addresses for protected data, and comparing these tags during load and store instructions to detect discrepancies, raising an alarm for attacks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If software bound checking, canary or double stack protection is used, then security against buffer overflow and stack attacks is improved, but performance deteriorates due to additional checking overhead
Solution Approach 1:
The colour memory is created at compilation time, pre-associating colour tags with memory addresses before execution. This preliminary preparation eliminates the need for runtime generation of protection data, reducing performance overhead while maintaining security
Solution Approach 2:
The colour memory creates a simplified copy of the program's memory address structure with associated colour tags. This copy allows rapid comparison operations without processing the entire program data, improving performance while providing comprehensive protection
2Reliability
If MPU (Memory Protection Unit) is used, then memory protection is provided, but granularity is insufficient to detect fine-grained attacks like buffer overflow
Solution Approach 1:
Each memory address is assigned a specific colour tag that provides fine-grained identification. This local differentiation allows precise detection of unauthorized memory accesses, such as buffer overflow attacks, by comparing colour tags at specific addresses rather than using coarse-grained MPU regions
Solution Approach 2:
The memory protection is segmented into individual address-level colour tags rather than using large MPU regions. This segmentation enables precise identification and protection of specific data structures and buffers, providing the granularity needed to detect fine-grained attacks
3Reliability
If security protection mechanisms are added to genuine programs, then security is improved, but the genuine program must be modified which increases complexity
Solution Approach 1:
The secure agent component acts as an intermediary between the CPU and memory, handling all colour tag comparisons and security checks. This mediator approach provides security protection without requiring modifications to the genuine program code, maintaining program simplicity while improving security
Data Source
AI summary
Provided is a system for execution protection using data colouring. The system includes a central processing unit (CPU), a system memory (SM) and a secure agent component (SAC). The SAC monitors memory access instructions occurring between the CPU and SM. The SAC comprises a colour memory (CM) storing a colour tag for each memory address of the system memory (SM). The SAC stores instructions at a destination address, and copies the colour tag stored at the instruction address in the colour memory to the destination address in the colour memory (CM) while storing data. The SAC loads instruction at a retrieval address, and compares the colour tag stored at the retrieval address and the colour tag at the load instruction in the colour memory (CM). A dysfunction is detected if colour tags are different. Other embodiments disclosed.