Differences

This shows you the differences between two versions of the page.

--- aslr [2018/08/18 14:24] – created rpjday
+++ aslr [2018/08/18 14:35] (current) – [Basics] rpjday
@@ Line 1: / Line 1: @@
 ===== Overview =====
-ASLR (Address Space Layout Randomization) stuff.
+ASLR (Address Space Layout Randomization) stuff (exec shield?).
 Links:
@@ Line 7: / Line 7: @@
   * [[https://lwn.net/Articles/569635/|Kernel address space layout randomization (LWN, 2013)]]
   * [[https://linux-audit.com/linux-aslr-and-kernelrandomize_va_space-setting/|Linux and ASLR: kernel/randomize_va_space]]
+  * [[https://securityetalii.es/2013/02/03/how-effective-is-aslr-on-linux-systems/|How Effective is ASLR on Linux Systems? (2013)]]
+Questions:
+  * What about kernel ASLR (KASLR)? Look for ''RANDOMIZE'' options.
+===== Basics =====
+Binaries must be position-independent executables, so worthless on statically-compiled binaries. Possible settings:
+  * 0 – No randomization. Everything is static.
+  * 1 – Conservative randomization. Shared libraries, stack, mmap(), VDSO and heap are randomized.
+  * 2 – Full randomization. In addition to elements listed in the previous point, memory managed through brk() is also randomized.
+===== Checking and changing =====
+Checking:
+<code>
+$ sysctl -a --pattern randomize
+kernel.randomize_va_space = 2
+$
+</code>
+Changing:
+<code>
+# echo 2 > /proc/sys/kernel/randomize_va_space
+# sysctl -w kernel.randomize_va_space=2
+</code>