Coprocessor Jump Address Authentication Against Buffer Overflow
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Solution Overview
Problem
Existing buffer overflow attack defenses, such as ASLR, DEP, and Stack Canary, are inadequate against complex attacks like Ret2libc, as they fail to secure dynamic link libraries and allow attackers to manipulate return addresses and function pointers.
Innovation Solution
A security defending method utilizing a coprocessor for encryption and authentication of destination addresses through a mask configuration and reference address management, ensuring secure storage and retrieval of encrypted return and function pointers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If ASLR mechanism is used to randomize memory addresses, then difficulty for attackers to jump to specific memory location is increased, but relative addresses between library functions remain unchanged allowing attackers to leak addresses through GOT table
Solution Approach 1:
The patent divides the address space into multiple segments with different protection levels. Virtual addresses are segmented into physical address components through page table structures, allowing differential security policies to be applied to different address regions. This segmentation enables fine-grained control over which address spaces require strong protection versus those that can use lighter protection mechanisms.
Solution Approach 2:
The patent introduces an intermediary security checking mechanism that sits between the CPU and memory access operations. This intermediary layer validates address accesses, checks permission bits, and mediates between the ASLR randomization and the actual memory access, preventing direct access to protected regions while allowing legitimate accesses through proper authentication.
2Reliability
If DEP mechanism is used to set non-executable attributes on data segments, then execution of injected malicious programs is prevented, but attackers can use existing dynamic link libraries or code segments to implement Ret2libc attacks
Solution Approach 1:
The patent applies preliminary anti-action by pre-configuring security attributes and permissions on memory regions before any code execution or data access occurs. Return addresses, function pointers, and other control flow data are pre-protected with specific permission bits that prevent both execution and unauthorized modification, countering Ret2libc attacks before they can be mounted by restricting what can be read, written, or executed in each region.
Solution Approach 2:
The patent dynamically changes security parameters such as permission bits and protection attributes based on the operational state and sensitivity of different memory regions. Critical regions like stack frames containing return addresses have stricter parameters (no execute, limited write), while code segments have different parameters (execute allowed, write restricted), allowing the system to adapt security strength to the specific function and context of each memory region.
3Reliability
If Stack Canary mechanism is used to insert Canary Word between buffer and return address, then overflow attack detection is improved, but system functions allowing Canary Word to be written make overflow attacks still feasible
Solution Approach 1:
The patent performs preliminary actions by setting up multiple layers of protection including permission bit configuration and security attribute assignment on the Canary Word and surrounding memory regions before buffer operations occur. The Canary Word is placed in a region with write-protected attributes that prevent both accidental and malicious overwrites, and the system pre-validates all write operations to ensure they don't compromise control flow data, detecting attacks before they can succeed.
Solution Approach 2:
The patent combines multiple security mechanisms into a composite protection structure. The Stack Canary is not used alone but is integrated with DEP-like non-executable attributes, ASLR-like address randomization, and permission bit-based access control. This composite approach creates overlapping security layers where each mechanism compensates for the weaknesses of others, making it significantly harder for attackers to bypass all protections simultaneously.
Data Source
AI summary
A security defending method and an electronic apparatus are disclosed. The security defending method is applicable in a coprocessor, including: receiving a jump destination encryption request for the operation task; using mask configuration to perform first mask processing on the first jump destination address value to obtain a first intermediate jump destination address value; performing an authentication operation based on the first jump destination storage address, a key reference value corresponding to the operation task and the first intermediate jump destination address value, to obtain a first encryption result value; using the mask configuration to perform second mask processing on the first encryption result value to obtain a first intermediate encryption result value; performing an authentication operation on the first intermediate encryption result value and the first jump destination address value to obtain a first encryption jump destination address value. The security defending method can prevent buffer overflow attacks.