FreeTDS Development Group

[Michael Peppler <mpeppler AT peppler.org>]

mjn writes:
 > > On Tue, Jan 02, 2001 at 11:51:49AM -0800, Michael Peppler wrote:
 > > >mjn writes:
 > > > > > my $sth = $dbh->prepare("SELECT * FROM authors WHERE state = 
 > > > > > \"$state\"");
 > > > > $state='"ca"';
 > > >    $state = 'ca';
 > > >    my $sth = $dbh->prepare("SELECT * FROM authors WHERE state = 
 > > > '$state'");
 > > >or use the q() and qq() operators, like so:
 > > >    my $sth = $dbh->prepare(qq(SELECT * FROM authors WHERE state = 
 > > > "$state"));
 > > 
 > > But all of these are vulnerable to attacks which include whatever the
 > > quoting character is - easily done if you're allowing outside input.
 > > The DBI::quote function was designed specifically to get around this
 > > problem, and will correctly quote _any_ string for use by the relevant
 > > database.
 > >
 > > $state=$dbh->quote($state);
 > > my $sth=$dbh->prepare("SELECT * FROM authors WHERE state = $state");
 > 
 > So what about using:
 > 
 > @configuration = qw(value1 value2 value3)
 > 
 > to pass information?  Is this unsafe like the rest of the instances we
 > have mentioned?

The problem is with char input that comes from a non-trusted source
(typically a CGI program) where clever use of the single and/or double
quote could cause some unwanted SQL to get executed.

For example:

    "update foo set xyz=1 where bar='$var'"

Now if $var = "mpeppler' delete from foo where bar!='" you could end
up with rather unwanted results...

For strings that are hard-coded in your program there is nothing to
worry about.

Michael
-- 
Michael Peppler - Data Migrations Inc. - mpeppler AT peppler.org
http://www.mbay.net/~mpeppler - mpeppler AT mbay.net
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