Blocking automated SQL injection

SQL injection vulnerabilities represent a majority percentage of security holes that end up resulting in a website being hacked. One of the most popular automated SQL injection tools in existence is Havij, which is especially popular because of its simplicity. Using it is pretty much a case of pointing it at a vulnerable URL and clicking a button. Its popularity is such that there are almost as many Google results for “havij sql” as there are for “automatic sql injection”.

I decided to take a look at Havij’s HTTP request footprint. Here’s what I got from a test attack:

/havij.php?id=1
/havij.php?id=-9.9
/havij.php?id=1%20and%201=1
/havij.php?id=1%20and%201=0
/havij.php?id=1'%20and%20'x'='x
/havij.php?id=1'%20and%20'x'='y
/havij.php?id=1"%20and%20"x"="x
/havij.php?id=1"%20and%20"x"="y
/havij.php?id=1%20and%201=1
/havij.php?id=1'
/havij.php?id=-999.9%20UNION%20ALL%20SELECT%200x31303235343830303536--
/havij.php?id=-999.9%20UNION%20ALL%20SELECT%200x31303235343830303536,0x31303235343830303536--
/havij.php?id=-999.9%20UNION%20ALL%20SELECT%200x31303235343830303536,0x31303235343830303536,0x31303235343830303536--
/havij.php?id=-999.9%20UNION%20ALL%20SELECT%200x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536--
/havij.php?id=-999.9%20UNION%20ALL%20SELECT%200x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536--
/havij.php?id=-999.9%20UNION%20ALL%20SELECT%200x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536--
/havij.php?id=-999.9%20UNION%20ALL%20SELECT%200x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536--
/havij.php?id=-999.9%20UNION%20ALL%20SELECT%200x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536--
/havij.php?id=-999.9%20UNION%20ALL%20SELECT%200x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536--
/havij.php?id=-999.9%20UNION%20ALL%20SELECT%200x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536--
/havij.php?id=-999.9%20UNION%20ALL%20SELECT%200x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536--
/havij.php?id=-999.9%20UNION%20ALL%20SELECT%200x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536--
/havij.php?id=-999.9%20UNION%20ALL%20SELECT%200x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536--
/havij.php?id=-999.9%20UNION%20ALL%20SELECT%200x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536--
/havij.php?id=-999.9%20UNION%20ALL%20SELECT%200x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536--
/havij.php?id=-999.9%20UNION%20ALL%20SELECT%200x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536--
/havij.php?id=-999.9%20UNION%20ALL%20SELECT%200x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536--
/havij.php?id=-999.9%20UNION%20ALL%20SELECT%200x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536--
/havij.php?id=-999.9%20UNION%20ALL%20SELECT%200x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536--
/havij.php?id=-999.9%20UNION%20ALL%20SELECT%200x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536--
/havij.php?id=-999.9%20UNION%20ALL%20SELECT%200x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536--
/havij.php?id=-999.9%20UNION%20ALL%20SELECT%200x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536--
/havij.php?id=-999.9%20UNION%20ALL%20SELECT%200x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536--
/havij.php?id=-999.9%20UNION%20ALL%20SELECT%200x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536--
/havij.php?id=-999.9%20UNION%20ALL%20SELECT%200x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536--
/havij.php?id=-999.9%20UNION%20ALL%20SELECT%200x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536--
/havij.php?id=-999.9%20UNION%20ALL%20SELECT%200x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536--
/havij.php?id=-999.9%20UNION%20ALL%20SELECT%200x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536--
/havij.php?id=-999.9%20UNION%20ALL%20SELECT%200x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536--
/havij.php?id=-999.9%20UNION%20ALL%20SELECT%200x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536--
/havij.php?id=-999.9%20UNION%20ALL%20SELECT%200x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536--
/havij.php?id=-999.9%20UNION%20ALL%20SELECT%200x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536--

The first two requests are used to find a keyword that is on both the valid page and an error page. The next 8 requests are used for recon to test if the site is vulnerable to SQL injections. The rest are UNION SELECT injections used to attempt to discover the column count in the SQL query. When the column count is correct, the repeated token will appear in the output of the page.

Interestingly, 0x31303235343830303536 is a token that Havij just happens to use. It represents “1025480056” in ASCII, which doesn’t seem to have any interesting properties. Perhaps the constant was encoded in little endian and it corresponds to the US cellphone number ‘560-084-5201’. Or, more likely, it was just chosen at random. What’s important is that it seems to be exactly the same every time you run it. A quick Google search supports this theory.

Anyway, the use of this constant is great news for anyone defending from SQL injection attacks. Just put the following PHP code in a common include (i.e. a script that gets included in every user-facing page) and it’ll prevent Havij from working:

<?php
foreach($_GET as $gv)
    if(strpos($gv, '0x31303235343830303536') !== FALSE) die('SQL injection attempt detected.');
foreach($_POST as $pv)
    if(strpos($pv, '0x31303235343830303536') !== FALSE) die('SQL injection attempt detected.');
foreach($_COOKIE as $cv)
    if(strpos($cv, '0x31303235343830303536') !== FALSE) die('SQL injection attempt detected.');
?>

Obviously this isn’t a replacement for proper filtering of data used in queries, but it’s a quick and effective way to ward the script kiddies away.

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