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SQL Statement refuses to complete itself in code

Posted on 2014-02-19
Last Modified: 2014-04-29
On my website, I get people to register and then I email then a link which verifies their email address is correct. The link is simply their email address in an encrpyted format which is decrpted when they return back to the verification page.

Encrpting Code and decrpt is here

Private Function EncryptString(strString)

Dim CharHexSet, intStringLen, strTemp, strRAW, i, intKey, intOffSet
Randomize Timer

intKey = Round((RND * 1000000) + 1000000)   '##### Key Bitsize
intOffSet = Round((RND * 1000000) + 1000000)   '##### KeyOffSet Bitsize

    If IsNull(strString) = False Then
         strRAW = strString
         intStringLen = Len(strRAW)
                   For i = 0 to intStringLen - 1
                        strTemp = Left(strRAW, 1)
                        strRAW = Right(strRAW, Len(strRAW) - 1)
                        CharHexSet = CharHexSet & Hex(Asc(strTemp) * intKey) & Hex(intKey)
         EncryptString = CharHexSet & "|" & Hex(intOffSet + intKey) & "|" & Hex(intOffSet)
         EncryptString = ""
    End If
End Function

Private Function DeCryptString(strCryptString)

Dim strRAW, arHexCharSet, i, intKey, intOffSet, strRawKey, strHexCrypData

    strRawKey = Right(strCryptString, Len(strCryptString) - InStr(strCryptString, "|"))
    intOffSet = Right(strRawKey, Len(strRawKey) - InStr(strRawKey,"|"))
    intKey = HexConv(Left(strRawKey, InStr(strRawKey, "|") - 1)) - HexConv(intOffSet)
    strHexCrypData = Left(strCryptString, Len(strCryptString) - (Len(strRawKey) + 1))
     arHexCharSet = Split(strHexCrypData, Hex(intKey))
         For i=0 to UBound(arHexCharSet)
              strRAW = strRAW & Chr(HexConv(arHexCharSet(i))/intKey)
    DeCryptString = strRAW
End Function

Private Function HexConv(hexVar)
Dim hxx, hxx_var, multiply          
         IF hexVar <> "" THEN
              hexVar = UCASE(hexVar)
              hexVar = StrReverse(hexVar)
              DIM hx()
              REDIM hx(LEN(hexVar))
              hxx = 0
              hxx_var = 0
              FOR hxx = 1 TO LEN(hexVar)
                   IF multiply = "" THEN multiply = 1
                   hx(hxx) = mid(hexVar,hxx,1)
                   hxx_var = (get_hxno(hx(hxx)) * multiply) + hxx_var
                   multiply = (multiply * 16)
              hexVar = hxx_var
              HexConv = hexVar
         END IF
End Function
Private Function get_hxno(ghx)
         If ghx = "A" Then
              ghx = 10
         ElseIf ghx = "B" Then
              ghx = 11
         ElseIf ghx = "C" Then
              ghx = 12
         ElseIf ghx = "D" Then
              ghx = 13
         ElseIf ghx = "E" Then
              ghx = 14
         ElseIf ghx = "F" Then
              ghx = 15
         End If
         get_hxno = ghx
End Function

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The verify page code is

 verifyid = Request.QueryString ("verifyid")

   emailid = DeCryptString (verifyid)

   strId  = CStr(emailid)
        LOGINSQL = "UPDATE tbl_members SET status = 'live' WHERE emailaddress = '" & strId &"'"
        response.Write LoginSQL
        Response.End ()
        set cmdHitting = Server.CreateObject("ADODB.Command")
            cmdHitting.ActiveConnection = DB_CON
            cmdHitting.CommandText = LOGINSQL
            cmdHitting.CommandType = 1
            cmdHitting.CommandTimeout = 0
            cmdHitting.Prepared = true

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My problem is the SQL statement LOGINSQL stops at the email address and does not read the append code for the closed apostrophe.
Question by:souldj
  • 2
LVL 33

Accepted Solution

Big Monty earned 168 total points
ID: 39872019
this is not a good way to build sql statements, google "sql injection" and you'll see why )

to fix this issue, you need to replace any single quotes with double quotes, so change

  strId  = CStr(emailid)


  strId  = CStr( Replace( emailid, "'", "''" ) )

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or you would be better of using parameterized queries
LVL 52

Assisted Solution

by:Scott Fell, EE MVE
Scott Fell,  EE MVE earned 166 total points
ID: 39872058
Are there special characters being sent to the url?  Maybe you need to urlencode the email before sending it to the url?  http://www.w3schools.com/Asp/met_urlencode.asp

Try and see what the input looks like
verifyid = Request.QueryString ("verifyid")
 emailid = DeCryptString (verifyid)
response.write verifyid&"<br>"&emailid
response.end ' for testing

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LVL 15

Assisted Solution

pateljitu earned 166 total points
ID: 39874121
I would agree with @Big Monty and @Scott Fell, it is better to replace single quotes to avoid SQL injection and also URL encode querystring

There seems to be some problem with decryption logic, but when I tried to wrap decrypted text around HTMLEncodeing I was able to view email address with complete SQL statement.

your verify code will looks as below:

verifyid = Request.QueryString ("verifyid")

   emailid = server.HTMLEncode(replace(DeCryptString(verifyid),"'","''"))

   strId  = CStr(emailid)
        LOGINSQL = "UPDATE tbl_members SET status = 'live' WHERE emailaddress = '" & strId 
        response.Write LoginSQL
        Response.End ()

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LVL 52

Expert Comment

by:Scott Fell, EE MVE
ID: 39874715
fyi... http://www.classicasp.org/ has just about everything you need including hash and encrypt/decrypt http://www.classicasp.org/lib/asp/org/classicasp/doc/index.htm 

You have to download the entire file, but you only have to upload the one file that has the functions.  All open source.

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