Transport Layer Security (TLS) Vulnerability

Number: AL14-039
Date: 9 December 2014


The purpose of this Alert is to bring attention to a recently identified vulnerability in devices using TLS 1.x.


Details of a vulnerability in Transport Layer Security (TLS) 1.x have recently been published by security researchers. Two months ago, an attack method known as POODLE (Padding Oracle On Downgraded Legacy Encryption) was disclosed in the SSL v3 protocol. This attack method can now be used to exploit a vulnerability the TLS 1.x protocol. Exploitation of the TLS protocol can be accomplished by providing incorrect TLS padding (always accepted) and providing pieces of 16 character cookie, that will enable the attacker to reconstruct the cookie in 4096 requests. A reconstructed cookie will allow an attacker to access encrypted communication. Any device that uses the TLS 1.x protocol could be affected by this vulnerability. In particular, this vulnerability can be leveraged to affect some popular networked devices such load balancers, by injecting malicious javascript in the web browser.

Software vendors and device manufacturers have not yet released patches to address this vulnerability but a workaround is available to temporarily mitigate this issue.

The National Vulnerability Database (NVD) provides a summary for each vulnerability and references to advisories, solutions and tools. CCIRC recommends monitoring this link closely for updates to vendor patches.


Suggested Action

CCIRC recommends that system administrators identify their affected assets and potential interdependencies with their organization’s critical services, and implement the mitigations described by their devices respective vendors. Public-facing network devices using TLS 1.x and client web browsers should be addressed as top priorities.


Note to Readers

In support of Public Safety's mission to build a safe and resilient Canada, CCIRC's mandate is to help ensure the security and resilience of the vital non-federal government cyber systems that underpin Canada's national security, public safety and economic prosperity. As Canada's computer security incident response team, CCIRC is Canada's national coordination centre for the prevention and mitigation of, preparedness for, response to, and recovery from cyber incidents on non-federal government systems. It does this by providing authoritative advice and support, and coordinating information sharing and incident response.

Please note, CCIRC PGP key has recently been updated.

For general information, please contact Public Safety Canada's Public Affairs division at:

Telephone: 613-944-4875 or 1-800-830-3118
Fax: 613-998-9589

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