Date: Wed, 06 Feb 2013 18:19:46 -0700 From: Kurt Seifried <kseifried@...hat.com> To: oss-security@...ts.openwall.com CC: Michael Koziarski <michael@...iarski.com>, rubyonrails-security@...glegroups.com, Steven Christey <coley@...re.org> Subject: Re: Potential Query Manipulation with Common Rails Practises -----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 Just a heads up, the CVE situation for these issues is complicated (multiple languages/interfaces/backends/applications are affected in various combinations). Mitre is aware of it and working on a response, so until then I'm holding off on assigning any CVEs. On 02/06/2013 03:51 PM, Michael Koziarski wrote: > Common patterns used in Ruby on Rails applications could allow an > attacker to generate SQL that, when combined with some database > server's typecasting code, generates queries that match incorrect > records. > > Note: This is a code and best-practise advisory, there is no patch > to apply or updated version to install. > > Databases Affected: MySQL, SQLServer and some configurations of > DB2 Not affected: SQLite, PostgreSQL, Oracle > > Outline ------- When comparing two values of differing types most > databases will either generate an error or return 'false'. Other > databases will attempt to convert those values to a common type to > enable comparison. > > For example in MySQL comparing a string with an integer will cast > the string into an integer. Given that any string which isn't an > invalid integer will convert to 0, this could allow an attacker to > bypass certain queries. > > If your application has XML or JSON parameter parsing enabled, an > attacker will be able to generate queries like this unless you > take care to typecast your input values. For example: > > User.where(:login_token=>params[:token]).first > > Could be made to generate the query: > > SELECT * FROM `users` WHERE `login_token` = 0 LIMIT 1; > > Which will match the first value which doesn't contain a valid > integer. This vulnerability affects multiple programming > languages, and multiple databases, be sure to audit your other > applications to see if they suffer the same issues. > > Work Arounds ------------ There are two options to avoid these > problems. The first is to disable JSON and XML parameter parsing. > Depending on the version of rails you use you will have to place > one of the following snippets in an application initializer > > Rails 3.2, 3.1 and 3.0: > ActionDispatch::ParamsParser::DEFAULT_PARSERS.delete(Mime::XML) > ActionDispatch::ParamsParser::DEFAULT_PARSERS.delete(Mime::JSON) > > Rails 2.3: ActionController::Base.param_parsers.delete(Mime::XML) > ActionController::Base.param_parsers.delete(Mime::JSON) > > If your application relies on accepting these formats you will have > to take care to explicitly convert parameters to their intended > types. For example: > > User.where(:login_token=>params[:token].to_s) > > > Fixes ----- Unfortunately it is not possible for ActiveRecord to > automatically protect against all instances of this attack due to > the API we expose. For example: > > User.where("login_token = ? AND expires_at > ?", params[:token], > Time.now) > > Without parsing the SQL fragments it is not possible to determine > what type params[:token] should be cast to. > > Future releases of Rails will contain changes to mitigate the risk > of this class of vulnerability, however as long as this feature is > still supported this risk will remain. > > Credits ------- Thanks to joernchen of Phenoelit for reporting this > to us and to Jonathan Rudenberg for helping to review the > advisory. > > - -- Kurt Seifried Red Hat Security Response Team (SRT) PGP: 0x5E267993 A90B F995 7350 148F 66BF 7554 160D 4553 5E26 7993 -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.13 (GNU/Linux) iQIcBAEBAgAGBQJREwEyAAoJEBYNRVNeJnmT4TMP/j5/9uvcYvXUsJJKe6bPrYh+ E1Cqf5+VI0j3runz6GmPj9acg7y3DJYVajKJFmJfebvfIx7WABXo9it04wNDGb3a 7AIJYmFSyJSP8gMfsj03uOQRD/c7xOMtMjQTbaLNbj5vzV1n80ACym4XxT87+v5L R7nxjBa1bgKuu/dc0BNMHRwynibBVPuTD38M42CLa9tfPBVP7vKGj5F/fVVAyPtk h6/+VAmIAxeCDeNhcdKaL690yGgTADAGznPvLi1UIEYynCFX6/I+Sd+9+PqN4vfB blXfHU0eqPxJWWGRHK4hXfcy0Xn2sguZvik1dJD74pnv4hsk9fxibtias+7odmL1 eVQIW0wnBDHwS/591u5c90ngsOTCHEzR6CG9D9DdtNdcn/BUcyi+3ZCUu/3JTJyv I+sqNhDTEI17VSuKlxY4+9u/tH8f7A1GUuyN8RbCx9aj6/cpQyqbE7P3N6mChIdy k9ClB9+6TDcNXLcNpaAuRrcv9fIPVTM9ss+GknG8UJcEcKJTMHGMrxK16rB7ty3W tnPWEBvcSsteJnzQPz7I+KuD5YLuH1XTmzjjhuGXDF5bAb40dG3jXjx8qoeSdZP7 Geu0OioG9fY8eOCRwEaZlCFOW+Q0NBNNVdHhaGpVaN9GKcDcuTIW+viSH6RfcDj2 iUIs7ozTugG3z0WHMWBT =Zxvd -----END PGP SIGNATURE-----
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