checksec

Bash version entering feature freeze

Checksec is a bash script to check the properties of executables (like PIE, RELRO, 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

Updates

** Version 2.7.x should be the last version of checksec in bash

Version 3.x will be released as a golang static binary Checksec was originally released with 1.0 in early 2009 and has been used for validating binary checks of Linux systems for over a decade. Over time as more checks were supported and Linux distributions have changed, this has brought more dependencies into checksec. Adding more and more dependenies to be able to check the security flags of files, it not an ideal solution for systems with minor dependencies including embedded systems, distroless containers, and cross platform checks.

• Feature partial between the bash version and the golang version will be mostly supported.
  • Adding support for yaml output
  • Removing support for CSV
  • JSON and XML will still both be supported
• Much faster results. When checking 694 files in a directory
  • bash: real 0m10.348s
  • golang: real 0m0.691s
• Adds recursive directory support TODO:
• Fix Partial RELRO
• Add fortify file function results
• Add fortifyProc
• Add ProcLibs
• Add selinux checks
• Add additional kernel flag checks
• Update and Validate all current tests
• Enable golint validation

For OSX

Most of the tools do not work on mach-O binaries or the OSX kernel, so it is not supported

Cosign Verify Checksec

cosign verify-blob --signature checksec_new.sig --certificate checksec_new.pub checksec [email protected] --certificate-oidc-issuer=https://github.com/login/oauth

Openssl Verify Checksec Openssl verification is being deprecated in favor of Cosign Verification, which is backed by a hardware security module and provides a greater level of intergrity.

openssl dgst -sha256 -verify checksec.pub -signature checksec.sig checksec

Examples

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

* 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'>
    <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" },{ "kernheap_config":"no" } }

Using with Cross-compiled Systems

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 configuration. 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.