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Exploits often use specific bytes to spray the heap, as the data stored on the heap serves multiple roles. During exploitation of a security issue, the application code can often be made to read an address from an arbitrary location in memory. This address is then used by the code as the address of a function to execute.
The term is general and can be used to describe a variety of techniques for bypassing heap protection strategies. The paper often credited with naming the technique, "Heap Feng Shui in JavaScript", [3] used it to refer to an exploit in which a dangling pointer was aligned with a portion of an
Stop-and-copy garbage collection in a Lisp architecture: [1] Memory is divided into working and free memory; new objects are allocated in the former. When it is full (depicted), garbage collection is performed: All data structures still in use are located by pointer tracing and copied into consecutive locations in free memory.
Illustration of the table-heap compaction algorithm. Objects that the marking phase has determined to be reachable (live) are colored, free space is blank. A table-based algorithm was first described by Haddon and Waite in 1967. [1] It preserves the relative placement of the live objects in the heap, and requires only a constant amount of overhead.
The techniques to exploit a buffer overflow vulnerability vary by architecture, operating system, and memory region. For example, exploitation on the heap (used for dynamically allocated memory), differs markedly from exploitation on the call stack. In general, heap exploitation depends on the heap manager used on the target system, while stack ...
A heap overflow, heap overrun, or heap smashing is a type of buffer overflow that occurs in the heap data area. Heap overflows are exploitable in a different manner to that of stack-based overflows. Memory on the heap is dynamically allocated at runtime and typically contains program data.
When a program is run, memory is often dynamically allocated in two places: the stack and the heap. Memory is continuously allocated on a stack but not on a heap, thus reflective of their names. Stack also refers to a programming construct, thus to differentiate it, this stack is referred to as the program's function call stack. Technically ...
For instance Firefox's JIT compiler for Javascript introduced this protection in a release version with Firefox 46. [34] JIT spraying is a class of computer security exploits that use JIT compilation for heap spraying: the resulting memory is then executable, which allows an exploit if execution can be moved into the heap.