are not available. It was noted in February 2012 that ASLR on 32-bit Windows systems prior to Windows 8 can have its effectiveness reduced in low memory situations. A similar effect also had been achieved on Linux in the same research. The test code caused the Mac OS X 10.7.3 system to kernel panic, so it was left unclear about its ASLR behavior in this scenario. NetBSD Support for ASLR in userland appeared in NetBSD 5.0 (released April 2009), and was enabled by default in NetBSD-current in April 2016. Kernel ASLR support on amd64 was added in NetBSD-current in October 2017, making NetBSD the first BSD system to support KASLR. OpenBSD In 2003, OpenBSD became the first mainstream operating system to support a strong form of ASLR and to activate it by default. OpenBSD completed its ASLR support in 2008 when it added support for PIE binaries. OpenBSD 4.4's malloc(3) was designed to improve security by taking advantage of ASLR and gap page features implemented as part of OpenBSD's mmap system call, and to detect use-after-free bugs. Released in 2013, OpenBSD 5.3 was the first mainstream operating system to enable position-independent executables by default on multiple hardware platforms, and OpenBSD 5.7 activated position-independent static binaries (Static-PIE) by default. macOS In Mac OS X Leopard 10.5 (released October 2007), Apple introduced randomization for system libraries. In Mac OS X Lion 10.7 (released July 2011), Apple expanded their implementation to cover all applications, stating "address space layout randomization (ASLR) has been improved for all applications. It is now available for 32-bit apps (as are heap memory protections), making 64-bit and 32-bit applications more resistant to attack." As of OS X Mountain Lion 10.8 (released July 2012) and later, the entire system including the kernel as well as kexts and zones are randomly relocated during system boot. Solaris ASLR has been introduced in Solaris beginning with Solaris 11.1 (released October 2012). ASLR in Solaris 11.1 can be set system-wide, per zone, or on a per-binary basis. Exploitation A side-channel attack utilizing branch target buffer was demonstrated to bypass ASLR protection. In 2017, an attack named "ASLR⊕Cache" was demonstrated which could defeat ASLR in a web browser using JavaScript. See also Buffer overflow Stack buffer overflow Stack-smashing protection NX bit References External links Exploit Mitigation Techniques: an Update After 10 Years in OpenBSD PaX documentation on ASLR Comparison of PaX to Exec Shield and