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AUSCERT Security Bulletin
ASB-2009.1075
Two vulnerabilities in Ruby on Rails
7 September 2009
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AusCERT Security Bulletin Summary
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Product: Ruby on Rails
Operating System: UNIX variants (UNIX, Linux, OSX)
Windows
Impact/Access: Cross-site Scripting -- Remote/Unauthenticated
Provide Misleading Information -- Remote/Unauthenticated
Resolution: Patch/Upgrade
CVE Names: CVE-2009-3009
Member content until: Wednesday, October 7 2009
OVERVIEW
Two vulnerabilities have been discovered in Ruby on Rails which can
cause Cross Site Scripting (XSS) and possible digest forging.
IMPACT
The vendor has provided the following information regarding the
vulnerabilities that have been corrected in versions 2.3.4 and 2.2.3:
"There is a vulnerability in the escaping code for the form helpers in
Ruby on Rails. Attackers who can inject deliberately malformed unicode
strings into the form helpers can defeat the escaping checks and inject
arbitrary HTML. Due to the way that most databases either dont accept
or actively cleanse malformed unicode strings this vulnerability is
most likely to be exploited by non-persistent attacks however
persistent attacks may still be possible in some configurations." [1]
"There is a weakness in the code Ruby on Rails uses to verify message
digests in the cookie store. Because it uses a non-constant time
algorithm to verify the signatures an attacker may be able to determine
when a forged signature is partially correct. By repeating this process
they may be able to successfully forge a digest. Due to issues like
network latency, non-deterministic GC runs and other issues it is
unlikely that this attack could be exploited in the wild within a
reasonable timeframe. However users should still upgrade as soon as
possible to remove the weakness" [2]
MITIGATION
Version 2.3.4 and 2.2.3 which correct these issues have been made
available on the vendors website. [1][2]
REFERENCES
[1] XSS Vulnerability in Ruby on Rails
http://weblog.rubyonrails.org/2009/9/4/xss-vulnerability-in-ruby-on-rails
[2] Timing Weakness in Ruby on Rails
http://weblog.rubyonrails.org/2009/9/4/timing-weakness-in-ruby-on-rails
AusCERT has made every effort to ensure that the information contained
in this document is accurate. However, the decision to use the information
described is the responsibility of each user or organisation. The decision to
follow or act on information or advice contained in this security bulletin is
the responsibility of each user or organisation, and should be considered in
accordance with your organisation's site policies and procedures. AusCERT
takes no responsibility for consequences which may arise from following or
acting on information or advice contained in this security bulletin.
If you believe that your computer system has been compromised or attacked in
any way, we encourage you to let us know by completing the secure National IT
Incident Reporting Form at:
http://www.auscert.org.au/render.html?it=3192
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Australian Computer Emergency Response Team
The University of Queensland
Brisbane
Qld 4072
Internet Email: auscert@auscert.org.au
Facsimile: (07) 3365 7031
Telephone: (07) 3365 4417 (International: +61 7 3365 4417)
AusCERT personnel answer during Queensland business hours
which are GMT+10:00 (AEST).
On call after hours for member emergencies only.
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