#!/bin/sh # Report the hardening characterists of a set of binaries. # Copyright (C) 2009, 2010 Kees Cook # License: GPLv2 or newer skip_pie=no skip_stackprotector=no skip_fortify=no skip_relro=no skip_bindnow=no quiet=no while getopts psfrbq opt do case "$opt" in p) skip_pie=yes ;; s) skip_stackprotector=yes ;; f) skip_fortify=yes ;; r) skip_relro=yes ;; b) skip_bindnow=yes ;; q) quiet=yes ;; [?]) echo >&2 "Usage: $0 [-p] [-s] [-f] [-r] [-b] file ..." echo >&2 " -p Do not require PIE binary" echo >&2 " -s Do not require stack protector" echo >&2 " -f Do not require fortify source" echo >&2 " -r Do not require RELRO markings" echo >&2 " -b Do not require BIND_NOW markings" echo >&2 " -q Only report failures" exit 1 ;; esac done shift $(( $OPTIND-1 )) overall=0 rc=0 report="" good () { if [ "$quiet" != "yes" ]; then report="$report $1" fi } bad () { report="$report $1" rc=1 } for file in "$@" do rc=0 report="$file:" PROG_REPORT=$(LANG=C readelf -lW "$file") if [ -z "$PROG_REPORT" ]; then rc=1; continue; fi DYN_REPORT=$(LANG=C readelf -dW "$file" 2>/dev/null) RELOC_REPORT=$(LANG=C readelf -sW "$file" 2>/dev/null | \ egrep ' FUNC .* UND ' | \ sed -re 's/ \([0-9]+\)$//g; s/.* //g; s/@.*//g;') # PIE # First, verify this is an executable, not a library. This seems to be # best seen by checking for the PHDR program header. name=" Position Independent Executable" if echo "$PROG_REPORT" | awk '{print $1}' | grep -q '^PHDR$'; then if echo "$PROG_REPORT" | grep -q '^Elf file type is DYN '; then good "$name: yes" else msg="$name: no, normal executable!" if [ "$skip_pie" = "yes" ]; then good "$msg (ignored)" else bad "$msg" fi fi else if echo "$PROG_REPORT" | grep -q '^Elf file type is DYN '; then good "$name: no, regular shared library (ignored)" else bad "$name: not a known ELF type!?" fi fi # Stack-protected name=" Stack protected" if echo "$RELOC_REPORT" | grep -q '^__stack_chk_fail$'; then good "$name: yes" else msg="$name: no, not found!" if [ "$skip_stackprotector" = "yes" ]; then good "$msg (ignored)" else bad "$msg" fi fi if echo "$RELOC_REPORT" | grep -q '^__stack_chk_fail$'; then good "$name: yes" else ### for OpenBSD if echo "$RELOC_REPORT" | grep -q '^__stack_smash_handler$'; then good "$name: yes" else msg="$name: no, not found!" if [ "$skip_stackprotector" = "yes" ]; then good "$msg (ignored)" else bad "$msg" fi fi fi # Fortified name=" Fortify Source functions" if echo "$RELOC_REPORT" | grep -q '^__.*_chk$'; then good "$name: yes" else msg="$name: no, not found!" if [ "$skip_fortify" = "yes" ]; then good "$msg (ignored)" else bad "$msg" fi fi # Format # unfortunately, I haven't thought of a way to test for this after # compilation. What it really needs is a lintian-like check that # reviews the build logs and looks for the warnings, or that the # argument is changed to use -Werror,format-security to stop the build. # RELRO name=" Read-only relocations" if echo "$PROG_REPORT" | awk '{print $1}' | grep -q '^GNU_RELRO$'; then good "$name: yes" else msg="$name: no, not found!" if [ "$skip_relro" = "yes" ]; then good "$msg (ignored)" else bad "$msg" fi fi # BIND_NOW name=" Immediate binding" if echo "$DYN_REPORT" | awk '{print $2}' | grep -q '^(BIND_NOW)$'; then good "$name: yes" else msg="$name: no, not found!" if [ "$skip_bindnow" = "yes" ]; then good "$msg (ignored)" else bad "$msg" fi fi if [ "$quiet" != "yes" ] || [ $rc -ne 0 ]; then echo "$report" fi if [ $rc -ne 0 ]; then overall=$rc fi done exit $overall :<<=cut =pod =head1 NAME hardening-check - check binaries for security hardening features =head1 SYNOPSIS Examine a given set of ELF binaries and check for several security hardening features, failing if they are not all found. =head1 DESCRIPTION This utility checks a given list of ELF binaries for several security hardening features that can be compiled into an executable. These features are: =over 8 =item B This indicates that the executable was built in such a way (PIE) that the "text" section of the program can be relocated in memory. To take full advantage of this feature, the executing kernel must support text Address Space Layout Randomization (ASLR). =item B This indicates that the executable was compiled with the L option B<-fstack-protector>. The program will be resistant to have its stack overflowed. =item B This indicates that the executable was compiled with B<-D_FORTIFY_SOURCE=2> and B<-O2> or higher. This causes certain unsafe glibc functions with their safer counterparts (e.g. strncpy instead of strcpy). =item B This indicates that the executable was build with B<-Wl,-z,relro> to have ELF markings (RELRO) that ask the runtime linker to mark any regions of the relocation table as "read-only" if they were resolved before execution begins. This reduces the possible areas of memory in a program that can be used by an attacker that performs a successful memory corruption exploit. =item B This indicates that the executable was built with B<-Wl,-z,now> to have ELF markings (BIND_NOW) that ask the runtime linker to resolve all relocations before starting program execution. When combined with RELRO above, this further reduces the regions of memory available to memory corruption attacks. =back =head1 OPTIONS =over 8 =item B<-p> No not require that the checked binaries be built as PIE. =item B<-s> No not require that the checked binaries be built with the stack protector. =item B<-f> No not require that the checked binaries be built with Fority Source. =item B<-r> No not require that the checked binaries be built with RELRO. =item B<-b> No not require that the checked binaries be built with BIND_NOW. =item B<-q> Only report failures. =back =head1 RETURN VALUE When all checked binaries have all checkable hardening features detected, this program will finish with an exit code of 0. If any check fails, the exit code with be 1. Individual checks can be disabled via command line options. =head1 AUTHOR Kees Cook =head1 COPYRIGHT AND LICENSE Copyright 2009 Kees Cook . This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; version 2 or later. =head1 SEE ALSO L, L =cut