NAME¶
hardening-check - check binaries for security hardening features
SYNOPSIS¶
hardening-check [options] [ELF ...]
Examine a given set of ELF binaries and check for several security hardening
features, failing if they are not all found.
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:
- Position Independent Executable
- 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).
- Stack Protected
- This indicates that there is evidence that the ELF was compiled with the
gcc(1) option -fstack-protector (e.g. uses
__stack_chk_fail). The program will be resistant to having its
stack overflowed.
When an executable was built without any character arrays being allocated on
the stack, this check will lead to false alarms (since there is no use of
__stack_chk_fail), even though it was compiled with the correct
options.
- Fortify Source functions
- This indicates that the executable was compiled with
-D_FORTIFY_SOURCE=2 and -O1 or higher. This causes certain
unsafe glibc functions with their safer counterparts (e.g. strncpy
instead of strcpy), or replaces calls that are verifiable at
runtime with the runtime-check version (e.g. __memcpy_chk insteade
of memcpy).
When an executable was built such that the fortified versions of the glibc
functions are not useful (e.g. use is verified as safe at compile time, or
use cannot be verified at runtime), this check will lead to false alarms.
In an effort to mitigate this, the check will pass if any fortified
function is found, and will fail if only unfortified functions are found.
Uncheckable conditions also pass (e.g. no functions that could be
fortified are found, or not linked against glibc).
- Read-only relocations
- This indicates that the executable was build with -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.
- Immediate binding
- This indicates that the executable was built with -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.
OPTIONS¶
- --nopie, -p
- No not require that the checked binaries be built as PIE.
- --nostackprotector, -s
- No not require that the checked binaries be built with the stack
protector.
- --nofortify, -f
- No not require that the checked binaries be built with Fority Source.
- --norelro, -r
- No not require that the checked binaries be built with RELRO.
- --nobindnow, -b
- No not require that the checked binaries be built with BIND_NOW.
- --quiet, -q
- Only report failures.
- --verbose, -v
- Report verbosely on failures.
- --report-functions, -R
- After the report, display all external functions needed by the ELF.
- --find-libc-functions, -F
- Instead of the regular report, locate the libc for the first ELF on the
command line and report all the known "fortified" functions
exported by libc.
- --color, -c
- Enable colorized status output.
- --lintian, -l
- Switch reporting to lintian-check-parsable output.
- --debug
- Report some debugging during processing.
- --help, -h, -?
- Print a brief help message and exit.
- --man, -H
- Print the manual page and exit.
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.
AUTHOR¶
Kees Cook <kees@debian.org>
COPYRIGHT AND LICENSE¶
Copyright 2009-2013 Kees Cook <kees@debian.org>.
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.
SEE ALSO¶
gcc(1),
hardening-wrapper(1)