Source: cve@mitre.org
An issue was discovered in the obstack crate before 0.1.4 for Rust. Unaligned references can occur.
CVE-2020-35894 exposes a critical vulnerability in the obstack crate for Rust, allowing for the creation of unaligned references. This can lead to memory corruption and potentially arbitrary code execution, posing a significant risk to systems utilizing this crate. Successful exploitation could result in a complete system compromise.
Step 1: Initialization: The vulnerable obstack crate is initialized within a Rust program.
Step 2: Memory Allocation: The program uses the obstack crate to allocate memory for storing data.
Step 3: Data Insertion: Data is written into the allocated memory regions.
Step 4: Unaligned Reference Creation: Due to the vulnerability, the crate creates an unaligned reference to a memory location. This can happen if the allocation doesn't respect the CPU's alignment requirements.
Step 5: Reference Usage: The program attempts to read or write data using the unaligned reference.
Step 6: Memory Corruption: The unaligned access triggers memory corruption. This could manifest as a crash, data corruption, or the ability to overwrite adjacent memory regions.
Step 7: Code Execution (Potential): If the memory corruption is carefully crafted, an attacker could overwrite critical program data, such as function pointers, to redirect program execution to attacker-controlled code, leading to arbitrary code execution.
The vulnerability stems from the obstack crate's handling of memory allocation and reference creation. Specifically, the flaw lies in the potential for the crate to generate unaligned references to data within the allocated memory. This occurs because the crate doesn't guarantee proper alignment when allocating and managing memory blocks. When a program attempts to access data through an unaligned reference, the CPU may encounter issues, leading to a crash or, more critically, the ability to overwrite memory. The root cause is likely a combination of incorrect pointer arithmetic and a lack of alignment checks during memory operations within the obstack crate. The lack of alignment can lead to read/write operations that cross page boundaries, leading to memory corruption and potentially arbitrary code execution.
There is no specific APT or malware known to be actively exploiting this vulnerability. However, the potential for arbitrary code execution makes it a high-value target for attackers. CISA KEV status: Not Listed.
Monitor for crashes or unexpected behavior in applications that use the obstack crate.
Analyze core dumps or crash reports for signs of memory corruption, such as invalid memory access errors.
Examine memory dumps for unaligned references or suspicious pointer values.
Implement runtime checks to verify memory alignment during allocation and access within the vulnerable code.
Use static analysis tools to identify potential alignment issues in the code.
Upgrade the obstack crate to version 0.1.4 or later.
Review and audit all code that uses the obstack crate to ensure proper memory management and alignment.
Implement memory safety best practices, such as using safe Rust constructs to prevent memory corruption.
Use a memory sanitizer (e.g., miri, valgrind) during development and testing to detect memory errors.
Regularly update all dependencies to the latest versions to address known vulnerabilities.