CWE-761: Free of Pointer not at Start of Buffer
Learn about CWE-761 (Free of Pointer not at Start of Buffer), its security impact, exploitation methods, and prevention guidelines.
What is Free of Pointer not at Start of Buffer?
• Overview: Free of Pointer not at Start of Buffer (CWE-761) occurs when a program attempts to free memory that was allocated on the heap using a pointer that does not point to the beginning of the allocated buffer. This can happen due to pointer arithmetic that adjusts the pointer away from its original allocation address.
• Exploitation Methods:
- Attackers can exploit this vulnerability by causing the program to free memory using an incorrect pointer, potentially leading to memory corruption.
- Common attack patterns include manipulating pointers through buffer overflows or incorrect pointer arithmetic to mislead the free operation.
• Security Impact:
- Direct consequences of successful exploitation include program crashes due to memory corruption.
- Potential cascading effects include the modification of critical program variables or unintended code execution.
- Business impact could be significant, including service downtime, data corruption, and increased risk of further attacks exploiting corrupted memory.
• Prevention Guidelines:
- Specific code-level fixes include ensuring that all pointers used with free() are always set to the start of the allocated buffer.
- Security best practices involve careful management of pointer arithmetic and thorough checks on pointers before freeing memory.
- Recommended tools and frameworks include static analysis tools to detect improper pointer usage and memory management issues, and adopting memory-safe programming languages where possible.
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Technical Details
Likelihood of Exploit: Not specified
Affected Languages: Not specified
Affected Technologies: Not specified