Code Review - SQL and Insertion Attacks (Warning: Not for Newbs)

Posted on 16th Feb 2014 07:03 pm by admin

Hey guys,

Its been a while, I know. Use to love coming here to answer peoples questions, but work and school have been keeping me too busy but do anything but lurk. I usually write all my code/apps by hand and over the past couple years created a common set of PHP functions that I implement on every site. This code continues to grow, and may become a framework one day (http://ryan.crawford.com/framework/default/). I wanted to present some of the crux functions for your consideration. Specifically I'd like to know what your best practices are in relation to preventing SQL insertion attacks, looking at the functions I use to control it:

Code: private $chars = array(
";" => "{00sc}", "'" => "{01sq}",
"!" => "{02ex}", "$" => "{03dl}",
"%" => "{04pr}", "<" => "{05ls}",
">" => "{06gt}", "=" => "{07eq}",
"&" => "{08an}", "#" => "{09pd}",
"," => "{10cm}", "/" => "{11fs}",
"*" => "{12as}", "\"=> "{13bs}"
);

/*
* Func: inject($str) - aptly named :)
* Desc: We'll be the only people doing SQL injection here
*/
function inject($str) {
return str_replace(array_keys($this->chars),
array_values($this->chars),$str);
}

/*
* Func: extract($str)
* Desc: Opposite of inject
*/
function extract($str) {
$str = str_replace(array_values($this->depc),
array_keys($this->depc),$str);

return str_replace(array_values($this->chars),
array_keys($this->chars),$str);
}

/*
* Func: query($query_data)
* Desc: Make a query on the database (SELECT)
* Note: If a log directory is defined, we will track queries
*/
function query($qdata) {
$result = mysql_query($qdata) or die("
Query: ".$qdata."

Issue: " . mysql_error());

// set the condition for the switch statement
$c = substr($qdata,0,strpos($qdata,' '));

if($c == "DELETE"||$c == "INSERT"||$c == "UPDATE") {
if(is_dir($this->cfg['logdir']))
$this->logLine($qdata,$this->cfg['qlog']);
return true;
}
if(mysql_num_rows($result)==0)
return false;

while($line = mysql_fetch_array($result,MYSQL_ASSOC)) {
$array_result[]=$this->extract($line);
}
return $array_result;
}

/*
* Func: iquery($array,$table)
* Desc: Insert data into the db(using just $_POST)
*/
function iquery($arr,$table) {
if(!$dataArr = $this->againstTable($arr,$table))
return false;
$n = 1;
// Loop to create SQL query
foreach($dataArr as $key => $value) {
$insertNames .= (sizeof($dataArr)==$n)? $key : $key.",";
$insertValues.= (sizeof($dataArr)==$n)? "'".$value."'" : "'".$value."',";
$n++;
}
$this->query("INSERT INTO ".$table." (".$insertNames.") VALUES (".$insertValues.");");
}


Basically, if you look at the array $chars, for inserted data I am searching for the keys and converting them to the values before insertion. It is a function I run all my inserts through. The query() function is what I do all my SELECTS with and it converts the characters back (the inject function encrypts, extract decrypts for lack of a better term). These are written object oriented so I still have access to PHP's extract if ever needed.

Question now being, what do you think of the effectiveness of this technique in terms of protecting against SQL injection? Are there ways to beat it? Are there better methods? Is this efficient? I'm not sure what algorithm PHP is using for str_replace, but the best ones don't run any faster than O(n). I don't think this runs any worse.

Your Answer:

Login to answer

Other forums

help finding hacking loopholes
i was attacked by a redirect php injection

my pc is clean of viruses

so i figure that

Just wondering what you think about my site
I am new to phpfreaks i just seen this form and thought it would be cool to see what other thought a

phpmailer class & pop.gmail.com?
Code: <?php
$mail->IsSMTP();
$mail->Host = "pop.gmail.com";

How to pass parameter to tag query?
Hi,
I want to get the value of a tag at a specific time (like 10/27/09 15:29:59), I need to giv

Access website from only 1 computer...?
One of my customers wants his website to only be accessed by people in which they bought the website

parameter passing issue on function
Well I thought I had created a pretty slick web page, using ?page and $_GET to load pages which wher

Array to string conversion
Can anyone help me with this?

Notice: Array to string conversion in /home/..../index.php on l

Sum of Values in an Array
This is probably really simple... but it's been years since I've written anything, so bare with me!<

Batch update record with Pagination
Hoping someone can help me with this issue I'm having, im trying to batch update records from a resu

ECC6 - Single sign-on
We are in the process of upgrading to ECC 6 which will support single sign on with user passwords al