Aaron Patterson (tenderlove) reports: Serialized Attributes YAML Vulnerability with Rails 2.3 and 3.0 There is a vulnerability in the serialized attribute handling code in Ruby on Rails 2.3 and 3.0, applications which allow users to directly assign to the serialized fields in their models are at risk of Denial of Service or Remote Code Execution vulnerabilities. This vulnerability has been assigned the CVE identifier CVE-2013-0277 Versions Affected: 2.3.x, 3.0.x and all earlier versions Not affected: 3.1.0 and Above Fixed Versions: None Impact ------ The +serialize+ helper in Active Record allows developers to store various objects serialized to a BLOB column in the database. The objects are serialized and deserialized using YAML. If developers allow their users to directly provide values for this attribute, an attacker could use a specially crafted request to cause the application to deserialize arbitrary YAML. Vulnerable applications will have models similar to this: class Post < ActiveRecord::Base serialize :tags end and will allow foreign input to be directly assigned to the serialized column like this: post = Post.new post.tags = params[:tags] All users running an affected release should either apply one of the patches or use one of the work arounds immediately. Releases -------- In accordance with our maintenance policy, there will be no new releases of Ruby on Rails 2.3 or 3.0 to address this vulnerability. The patches included below have been pushed to the relevant branches in git. Workarounds ----------- To work around this issue, you must ensure that users cannot assign directly to the serialized column. For example if you have a model Post which serializes an array of tags you should use attr_accessible to prevent attackers from changing these values directly: class Post < ActiveRecord::Base serialize :tags # because :tags isn't included in the accessible list, it will be protected from assignment by attackers. attr_accessible :title, :content end Note: There are additional security concerns caused by allowing your users to directly provide values for a serialized attribute like this. You should consider making this change even if you apply the patches. Patches ------- To aid users who are still running 2.3 or 3.0, we have included patches against this vulnerability. They are in git-am format and consist of a single changeset. * 2-3-serialize.patch - Patch for 2.3 series * 3-0-serialize.patch - Patch for 3.0 series Please note that only the 3.1.x and 3.2.x series are supported at present. Users of earlier unsupported releases are advised to upgrade as soon as possible as we cannot guarantee the continued availability of security fixes for unsupported releases. Credits ------- Thanks to Tobias Kraze for reporting this issue to us and working with us on the fix.
Created attachment 696264 [details] 2-3-serialize-cve-2013-0277.patch
Created attachment 696265 [details] 3-0-serialize-cve-2013-0277.patch
Public via: https://groups.google.com/forum/?fromgroups=#!topic/rubyonrails-security/KtmwSbEpzrU http://thread.gmane.org/gmane.comp.security.oss.general/9351
Could you please create tracking bug for Fedora? Thank you.
rubygem-activerecord-3.0.11-6.fc17 has been pushed to the Fedora 17 stable repository. If problems still persist, please make note of it in this bug report.
Created rubygem-activesupport tracking bugs for this issue Affects: fedora-all [bug 949207]
(In reply to comment #7) > Could you please create tracking bug for Fedora? Thank you. Apologies, next time can you mark this as needinfo? Created tracking bug #949207
Comment removed due to typo.
Acknowledgements: Red Hat would like to thank the Ruby on Rails project for reporting this issue. The Ruby on Rails project acknowledges Tobias Kraze as the original reporter.