Is address space layout randomization?

Is address space layout randomization?

Address space layout randomization (ASLR) is a memory-protection process for operating systems (OSes) that guards against buffer-overflow attacks by randomizing the location where system executables are loaded into memory. ASLR is able to put address space targets in unpredictable locations.

What is the main idea of address space randomization?

ASLR mixes up the address space of the vulnerable process—the main program, its dynamic libraries, the stack and heap, memory-mapped files, and so on—so that exploit payloads must be uniquely tailored to however the address space of the victim process is laid out at the time.

What Linux variable controls address space layout randomization ASLR settings?

ASLR can locate the base, libraries, heap, and stack at random positions in a process’s address space, which makes it difficult for an attacking program to predict the memory address of the next instruction. ASLR is built into the Linux kernel and is controlled by the parameter /proc/sys/kernel/randomize_va_space .

How does address space randomization work?

Address space layout randomization is based upon the low chance of an attacker guessing the locations of randomly placed areas. Security is increased by increasing the search space. Thus, address space randomization is more effective when more entropy is present in the random offsets.

Can ASLR be bypassed?

To bypass ASLR, an attacker typically needs to find an “information leak” type of vulnerability that leaks memory locations; or the attacker can probe the memory until they find the proper location where another app runs and then modify their code to target that memory address space.

How ASLR affects the stack?

ASLR is a technique designed to make various types of buffer overruns more difficult to exploit, by moving segments around a bit. The stack could be shifted a few bytes (or pages), the sections of your program (and even the libraries your code uses) can be loaded at different addresses, etc.

How random is ASLR?

The memory address can vary among trillions of values for a 64-bit operating system that allows ASLR to randomize 48 bits of the memory offset.