Re: SQL injection (no single quotes used)

["Adam Tuliper" <amt () gecko-software com>]

Michael Howard (and David LeBlanc) has a nice section in
"writing secure code" about encoding characters. In some
cases using char(0x27) as well as using entire words
encoded via 0xXXXXXXXXXX can be used. Watching for "'" is
not enough.
I think Michael is on this list.. any words Michael?



On Thu, 9 Dec 2004 09:53:03 -0600 (CST)
 Juan Carlos Calderon <johnccr () yahoo com> wrote:
> Hi all
>
> While in Oracle escaping apostrophe (') character
> seems to be enough protection for Sql Injection (I
> think is not), this is not true for Sql Server. Here a
> little example I think many of you will find useful.
>
> For an on-the-fly query like:
> Query = "select field1, field2... from table where id
> = '" + FixSQL (FieldValue) + "'"
>
> Where FixSQL will escape single quotes AKA apostrophe,
> the following value for "FieldValue" will be
> effective:
>
> FieldValue = "(NewLine)GO(NewLine)Desired Sql
> Sentence(NewLine)GO"
>
> Final result is:
> select field1, field2... from table where id = '
> GO
> Desired Sql Sentence
> GO
> '
>
> Here the MS Documentation for GO Keyword:
> <snip>
> SQL Server utilities interpret GO as a signal that
> they should send the current batch of Transact-SQL
> statements to SQL Server. The current batch of
> statements is composed of all statements entered since
> the last GO, or since the start of the ad hoc session
> or script if this is the first GO
> </snip>
>
> So one sentence become three, sentences one and three
> will fail, but sentence two (the one of our interest)
> will execute successfully.
>
> Hope you find this interesting
>
> Cheers,
> -JC
>
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