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Older versions of noVNC allow session theft


Commonly packaged versions of noVNC allow an attacker to hijack user sessions even when TLS is enabled. noVNC fails to set the secure flag when setting cookies containing an authentication token.

Affected Services / Software

Nova, when embedding noVNC prior to v0.5


Versions of noVNC prior to October 28, 2013 do not properly set the secure flag on cookies for pages served over TLS. Since noVNC stores authentication tokens in these cookies, an attacker who can modify user traffic can steal these tokens and connect to the VNC session.

Affected deployments can be identified by looking for the "secure" flag on the token cookie set by noVNC on TLS-enabled installations. If the secure flag is missing, the installation is vulnerable.

At the time of writing, Debian, Ubuntu and Fedora do not provide versions of this package with the appropriate patch.

Recommended Actions

noVNC should be updated to version 0.5 or later. If this is not possible, the upstream patch should be applied individually.

Upstream patch: https://github.com/kanaka/noVNC/commit/ad941faddead705cd611921730054767a0b32dcd

Contacts / References