Definition
ASLR is a security approach used in operating systems to overcome memory-related vulnerabilities. The technique randomizes memory addresses of system executables, stacks, and heaps, making it difficult for attackers to predict the memory layout and exploit weaknesses.
ASLR History
- 2001: Due to the increasing buffer overflow attacks, the PaX project is implemented to address the issue in the Linux Kernel.
- 2003: OpenBSD incorporates a similar feature.
- 2005: Linux integrates ASLR into its kernel, starting with 2.6.12.
- 2007: Apple introduces ASLR in Mac OS X Leopard (10.5) while Microsoft adds it as a new feature in Windows Vista.
- 2011: Apple integrates ASLS to iOS 4.3.
Benefits of ASLR
- System-wide protection: ASLR runs on the system level to protect all applications and processes.
- Difficult to exploit: The attackers cannot predict the memory layout or where specific code is located in the system. It makes it difficult for memory-related attacks such as return-to-libc and buffer overflow attacks.
ASLR Limitations
- Limited entropy: The randomness(entropy) level in memory address allocation depends on system architecture. 64-bit systems have more entropy than 32-bit systems.
- Information leakage: If attackers find the memory layout, they can bypass ASLR and target memory addresses where key data is loaded.
ASLR Application
- Application software: ASLR can enhance application security if integrated during development. Developers can reduce overall system vulnerabilities and protect users from potential exploits.
- Web Browsers: Browsers can use ASLR to randomize the address space layout, making it difficult for attackers to exploit browser vulnerabilities.
- Operating system: ASL protects all applications and processes installed on the operating system.