If the eval is removed then the CAPTCHA solution won’t ever be evaluated correctly. THe value of $x is the result of the CAPTCHA equation after it is evaluated. If $a = 2 and $b = 3 then $x should be 5 but if you take the eval out, $x will be the string “2 + 3” which won’t satisfy the CAPTCHA. Maybe there is a different way to do it but simply removing the eval will render the CAPTCHA broken.
Hi. I just started using this plugin and I too am concerned about the use of eval() since it poses a security risk.
Maybe I can help. I believe replacing lines 773776 with this code will do the same as the eval, but in a typesafe way:
function calculate2( $a, $op, $b ) {
switch( $op ){
case '+': return $a + $b;
case '': return $a  $b;
case '*': return $a * $b;
}
return null;
}
if ((int)$wpgform_options['captcha_terms'] === 2)
$x = calculate2( $a, $op1, $b );
else if( $op1 == '*'  $op2 == '' )
$x = calculate2( calculate2( $a, $op1, $b ), $op2, $c );
else
$x = calculate2( $a, $op1, calculate2( $b, $op2, $c ) );
This code tests to see if the first operator is * or the second is , because that will determine the order of operations, whether the answer is ($a $op1 $b) $op2 $c
as opposed to $a $op1 ($b $op2 $c)
. I used this table to figure out what the logic should be, and I think it checks out.
// a * b + c // *+ should be (a * b) + c
// a * b  c // + should be (a * b)  c
// a + b  c // + should be (a + b)  c
// a  b  c //  should be (a  b)  c
// a * b * c // ** could be either (a * b) * c or a * (b * c)
// a + b * c // +* should be a + (b * c)
// a  b * c // * should be a  (b * c)
// a  b + c // + should be a  (b + c)
// a + b + c // ++ could be either (a + b) + c or a + (b + c)

This reply was modified 6 years, 2 months ago by victorbargains.

This reply was modified 6 years, 2 months ago by victorbargains. Reason: fixing code formatting
I have finally had a chance to incorporate this suggestion in the plugin. It could use some testing before I push it out. I have posted it on my web site.