From e502de1ab04336007ecfff9e534abdaa9b0344d9 Mon Sep 17 00:00:00 2001 From: Xi Ruoyao Date: Sun, 11 Sep 2022 11:35:06 +0800 Subject: gcc: some reword of PIE/SSP/ASLR note Expand tabs to 8 spaces like everywhere else in the book. Explain that shared libraries are already covered by ASLR, PIE expands the ASLR to cover the exetutables. In 2022, stack smashing attackings are mostly constructing a sequence of faked returning addresses to exectute a series of function already existing in the programs or libraries itself (ret2lib). Returning into the code injected by the attacker is almost impossible because on i686 (with a PAE/NX enabled kernel) or x86_64, running injected code needs W/X mappings and those are very rare these days. --- chapter08/gcc.xml | 17 ++++++++++------- 1 file changed, 10 insertions(+), 7 deletions(-) (limited to 'chapter08') diff --git a/chapter08/gcc.xml b/chapter08/gcc.xml index 171808df2..fe8e767d1 100644 --- a/chapter08/gcc.xml +++ b/chapter08/gcc.xml @@ -108,18 +108,21 @@ cd build - PIE (position independent executable) is a technique to produce - binary programs that can be loaded anywhere in memory. Together - with a feature named ASLR (Address Space Layout Randomization), - this allows programs to never have the same memory layout, - thus defeating attacks based on reproducible memory patterns. + PIE (position-independent executable) is a technique to produce + binary programs that can be loaded anywhere in memory. Without PIE, + the security feature named ASLR (Address Space Layout Randomization) + can be applied for the shared libraries, but not the exectutable + itself. Enabling PIE allows ASLR for the executables in addition to + the shared libraries, and mitigates some attacks based on fixed + addresses of sensitive code or data in the executables. SSP (Stack Smashing Protection) is a technique to ensure that the parameter stack is not corrupted. Stack corruption can for example alter the return address of a subroutine, - which would allow transferring control to an attacker program instead - of the original one. + which would allow transferring control to some dangerous code + (existing in the program or shared libraries, or injected by the + attacker somehow) instead of the original one. -- cgit v1.2.3-54-g00ecf