Memory Alignment Randomization for Heap Exploit Mitigation
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Solution Overview
Problem
Conventional methods for mitigating heap exploits focus on randomizing memory positions within heap areas but still align memory addresses based on CPU configurations (multiples of 4 or 8), leading to potential performance degradation and vulnerability to attacks, as attackers can predict memory start addresses.
Innovation Solution
A method that randomizes memory alignment by adding a random value to the start address of memory allocation, ensuring objects are aligned without fixed alignment to multiples of 4 or 8, and includes a specific range for random value selection to prevent performance degradation and enhance security.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If memory addresses are aligned at multiples of 4 or 8 based on CPU configuration, then CPU access speed is optimized, but memory address predictability increases making systems vulnerable to heap exploits
Solution Approach 1:
The patent changes the memory alignment parameter from fixed multiples of 4 or 8 to random values. The heap allocator adds a random offset to the base address, so instead of always aligning to 4 or 8 byte boundaries, the alignment value becomes a random parameter that changes per allocation, preventing attackers from predicting memory addresses while the system adapts to modern CPU architectures that handle unaligned access efficiently
Solution Approach 2:
The patent makes the memory alignment dynamic rather than static. The alignment value is not fixed but changes randomly for each memory allocation. This dynamic approach ensures that even though the CPU prefers aligned access, the system adapts by using random alignment values that prevent exploitation while maintaining acceptable performance through modern CPU capabilities
2Object-affected harmful factors
If memory positions of objects inside heap areas are randomized, then heap exploit vulnerability is reduced, but memory access performance may degrade due to unaligned access
Solution Approach 1:
The patent changes the alignment parameter from fixed CPU-dependent values to random values. By modifying how alignment is calculated (using random offsets instead of fixed multiples), the system achieves both goals: randomization for security and maintained performance through efficient handling of the new parameter regime by modern CPUs
3Object-affected harmful factors
If a random value is added to the return start address to calculate the object start address, then memory address predictability is reduced mitigating heap exploits, but memory alignment precision is compromised
Solution Approach 1:
The patent deliberately changes the alignment precision parameter by introducing random offsets. Instead of maintaining precise alignment to fixed boundaries, the system accepts variable alignment as a feature rather than a bug, transforming the precision parameter from a fixed high-value state to a random variable state that provides security while remaining functional
Data Source
AI summary
A memory alignment randomization method of a memory heap exploit is provided, memory alignment of objects inside a heap area is randomly performed to mitigate the exploits of the vulnerability of the software memory heap area The heap exploit is powerfully mitigated by aligning randomly obtained memory addresses instead of aligning memory addresses at multiples of 4 or 8 when the memory alignment for the objects inside the heap area.