Checksec is a bash script to check the properties of executables (like PIE, RELRO, PaX, Canaries, ASLR, Fortify Source). It has been originally written by Tobias Klein and the original source is available here: http://www.trapkit.de/tools/checksec.html
** MAJOR UPDATES ** 2.1.0
- Changed structure to be more modular and switched to getopts so options can be in any order. e.g. format=json can be at the end now, however.
- All options now require
--$option=$valueinstead of--$option $value - --extended option now includes clang CFI and safe stack checks
Last Update: 2020-08-15
Most of the tools do not work on mach-O binaries or the OSX kernel, so it is not supported
Manually verify checksec
openssl dgst -sha256 -verify checksec.pub -signature checksec.sig checksec
normal (or --format=cli)
$checksec --file=/bin/ls
RELRO STACK CANARY NX PIE RPATH RUNPATH FILE
Partial RELRO Canary found NX enabled No PIE No RPATH No RUNPATH /bin/ls
csv
$ checksec --output=csv --file=/bin/ls
Partial RELRO,Canary found,NX enabled,No PIE,No RPATH,No RUNPATH,/bin/ls
xml
$ checksec --output=xml --file=/bin/ls
<?xml version="1.0" encoding="UTF-8"?>
<file relro="partial" canary="yes" nx="yes" pie="no" rpath="no" runpath="no" filename='/bin/ls'/>
json
$ checksec --output=json --file=/bin/ls
{ "file": { "relro":"partial","canary":"yes","nx":"yes","pie":"no","rpath":"no","runpath":"no","filename":"/bin/ls" } }
Fortify test in cli
$ checksec --fortify-proc=1
* Process name (PID) : init (1)
* FORTIFY_SOURCE support available (libc) : Yes
* Binary compiled with FORTIFY_SOURCE support: Yes
------ EXECUTABLE-FILE ------- . -------- LIBC --------
FORTIFY-able library functions | Checked function names
-------------------------------------------------------
fdelt_chk | __fdelt_chk
read | __read_chk
syslog_chk | __syslog_chk
fprintf_chk | __fprintf_chk
vsnprintf_chk | __vsnprintf_chk
fgets | __fgets_chk
strncpy | __strncpy_chk
snprintf_chk | __snprintf_chk
memset | __memset_chk
strncat_chk | __strncat_chk
memcpy | __memcpy_chk
fread | __fread_chk
sprintf_chk | __sprintf_chk
SUMMARY:
* Number of checked functions in libc : 78
* Total number of library functions in the executable: 116
* Number of FORTIFY-able functions in the executable : 13
* Number of checked functions in the executable : 7
* Number of unchecked functions in the executable : 6
Kernel test in Cli
$ checksec --kernel
* Kernel protection information:
Description - List the status of kernel protection mechanisms. Rather than
inspect kernel mechanisms that may aid in the prevention of exploitation of
userspace processes, this option lists the status of kernel configuration
options that harden the kernel itself against attack.
Kernel config: /proc/config.gz
GCC stack protector support: Enabled
Strict user copy checks: Disabled
Enforce read-only kernel data: Disabled
Restrict /dev/mem access: Enabled
Restrict /dev/kmem access: Enabled
* grsecurity / PaX: Auto GRKERNSEC
Non-executable kernel pages: Enabled
Non-executable pages: Enabled
Paging Based Non-executable pages: Enabled
Restrict MPROTECT: Enabled
Address Space Layout Randomization: Enabled
Randomize Kernel Stack: Enabled
Randomize User Stack: Enabled
Randomize MMAP Stack: Enabled
Sanitize freed memory: Enabled
Sanitize Kernel Stack: Enabled
Prevent userspace pointer deref: Enabled
Prevent kobject refcount overflow: Enabled
Bounds check heap object copies: Enabled
JIT Hardening: Enabled
Thread Stack Random Gaps: Enabled
Disable writing to kmem/mem/port: Enabled
Disable privileged I/O: Enabled
Harden module auto-loading: Enabled
Chroot Protection: Enabled
Deter ptrace process snooping: Enabled
Larger Entropy Pools: Enabled
TCP/UDP Blackhole: Enabled
Deter Exploit Bruteforcing: Enabled
Hide kernel symbols: Enabled
* Kernel Heap Hardening: No KERNHEAP
The KERNHEAP hardening patchset is available here:
https://www.subreption.com/kernheap/
Kernel Test in XML
$ checksec --output=xml --kernel
<?xml version="1.0" encoding="UTF-8"?>
<kernel config='/boot/config-3.11-2-amd64' gcc_stack_protector='yes' strict_user_copy_check='no' ro_kernel_data='yes' restrict_dev_mem_access='yes' restrict_dev_kmem_access='no'>
<grsecurity config='no' />
<kernheap config='no' />
</kernel>
Kernel Test in Json
$ checksec --output=json --kernel
{ "kernel": { "KernelConfig":"/boot/config-3.11-2-amd64","gcc_stack_protector":"yes","strict_user_copy_check":"no","ro_kernel_data":"yes","restrict_dev_mem_access":"yes","restrict_dev_kmem_access":"no" },{ "grsecurity_config":"no" },{ "kernheap_config":"no" } }
The checksec tool can be used against cross-compiled target file-systems offline. Key limitations to note:
-
Kernel tests - require you to execute the script on the running system you'd like to check as they directly access kernel resources to identify system configuration/state. You can specify the config file for the kernel after the -k option.
-
File check - the offline testing works for all the checks but the Fortify feature. Fortify, uses the running system's libraries vs those in the offline file-system. There are ways to workaround this (chroot) but at the moment, the ideal configuration would have this script executing on the running system when checking the files.
The checksec tool's normal use case is for runtime checking of the systems configruation. If the system is an embedded target, the native binutils tools like readelf may not be present. This would restrict which parts of the script will work.
Even with those limitations, the amount of valuable information this script provides, still makes it a valuable tool for checking offline file-systems.