It's hard to imagine a sensible application where an (untrusted) input data value for an SQL operation would properly include a call to an SQL-internal function. Something like "NOW()" would either be an invariant (hard-coded) piece of the SQL statement, or else would be something that is assembled and added to the SQL (or not) based on the presence/absence/value of some input parameter(s).

In the latter case, the value(s) of the parameter(s) would not go directly into the SQL string, but would only be tested to figure out what function call(s), if any, should be added (as literals) to the SQL. Example: 

my @flds = ( qw/foo bar status/ );
my @vals = @param{@flds};
my $valstr = join( ",", ("?") x @flds );

if ( $param{timestamp} ) {
    push @flds, "timestamp";
    $valstr .= ",NOW()";
}
my $sql = "insert into mytable (" . join( ",", @flds ) . ") values ($v
+alstr)";
my $sth = $dbh->prepare( $sql );
$sth->execute( @vals );

[download]
There are other ways to handle this that would suffice (e.g. careful regex matches on untrusted values in order to include things in the SQL statement), but as a rule, the application should have a limited inventory of function calls that it supports/allows.

In reply to Re^7: Removing malicious HTML entities (now with more questions!) by graff
in thread Removing malicious HTML entities (now with more questions!) by Lawliet

Title:
Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
to format your post, it's "PerlMonks-approved HTML":


  • Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!
  • Titles consisting of a single word are discouraged, and in most cases are disallowed outright.
  • Read Where should I post X? if you're not absolutely sure you're posting in the right place.
  • Please read these before you post! —
  • Posts may use any of the Perl Monks Approved HTML tags:
    a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, details, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, summary, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr
  • You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)
            For:     Use:
    & &amp;
    < &lt;
    > &gt;
    [ &#91;
    ] &#93;
  • Link using PerlMonks shortcuts! What shortcuts can I use for linking?
  • See Writeup Formatting Tips and other pages linked from there for more info.