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Thursday, April 24, 2008
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Mass SQL Injection Posted by Patrik @ 03:59 GMT

There's another round of mass SQL injections going on which has infected hundreds of thousands of websites.

Performing a Google search results in over 510,000 modified pages.


Google Search Results for SQL Injections

As more and more websites are using database back-ends to make them faster and more dynamic, it also means that it's crucial to verify what information gets stored in or requested from those databases — especially if you allow users to upload content themselves which happens all the time in discussion forums, blogs, feedback forms, et cetera.

Unless that data is sanitized before it gets saved you can't control what the website will show to the users. This is what SQL injection is all about, exploiting weaknesses in these controls. In this case the injection code starts off like this (note, this is not the complete code):

   DECLARE%20@S%20NVARCHAR(4000);SET%20@S=CAST(0x440045004300
   4C00410052004500200040005400200076006100720063006800610072
   00280032003500350029002C0040004300200076006100720063006800
   610072002800320035003500290020004400450043004C004100520045
   0020005400610062006C0065005F0043007500720073006F0072002000
   43005500520053004F005200200046004F0052002000730065006C0065
   0063007400200061002E006E0061006D0065002C0062002E006E006100
   6D0065002000660072006F006D0020007300790073006F0062006A0065
   00630074007300200061002C0073007900730063006F006C0075006D00
   6E00730020006200200077006800650072006500200061002E00690064
   003D0062002E0069006400200061006E006400200061002E0078007400
   7900700065003D00270075002700200061006E0064002000280062002E
   00780074007900700065003D003900390020006F007200200062002E00
   780074007900700065003D003300350020006…

Which when decoded becomes:

   DECLARE @T varchar(255)'@C varchar(255) DECLARE Table_Cursor
   CURSOR FOR select a.name'b.name from sysobjects a'syscolumns b
   where a.id=b.id and a.xtype='u' and (b.xtype=99 or b.xtype=35
   or b…

What happens as a result? It finds all text fields in the database and adds a link to malicious javascript to each and every one of them which will make your website display them automatically. So essentially what happened was that the attackers looked for ASP or ASPX pages containing any type of querystring (a dynamic value such as an article ID, product ID, et cetera) parameter and tried to use that to upload their SQL injection code.

So far three different domains have been used to host the malicious content — nmidahena.com, aspder.com and nihaorr1.com. There's a set of files that gets loaded from these sites that attempts to use different exploits to install an online gaming trojan. Right now the initial exploit page on all domains are unaccessible but that could change. So if you're a firewall administrator we recommend you to block access to them.

So what should you do?

First of all, search your website logs for the code above and see if you've been hit. If so, clean up your database to prevent your website visitors from becoming infected. Second, make sure that all the data you pass to your database is sanitized and that no code elements can be stored there. Third, block access to the sites above. Fourth, make sure the software you use is patched, F-Secure Health Check is an easy way to do this. Fifth, keep your antivirus solution up-to-date.

UPDATE: We've received some questions on the platform and operating systems affected by this attack. So far we've only seen websites using Microsoft IIS Web Server and Microsoft SQL Server being hit. Do note that this attack doesn't use vulnerabilities in any of those two applications. What makes this attack possible is poorly written ASP and ASPX (.net) code.





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