In snapd versions prior to 2.62, when using AppArmor for enforcement of sandbox permissions, snapd failed to restrict writes to the $HOME/bin
path. In Ubuntu, when this path exists, it is automatically added to
the users PATH. An attacker who could convince a user to install a
malicious snap which used the 'home' plug could use this vulnerability
to install arbitrary scripts into the users PATH which may then be run
by the user outside of the expected snap sandbox and hence allow them
to escape confinement.
In snapd versions prior to 2.62, when using AppArmor for enforcement of sandbox permissions, snapd failed to restrict writes to the $HOME/bin path. In Ubuntu, when this path exists, it is automatically added to the users PATH. An attacker who could convince a user to install a malicious snap which used the 'home' plug could use this vulnerability to install arbitrary scripts into the users PATH which may then be run by the user outside of the expected snap sandbox and hence allow them to escape confinement.
Neil McPhail discovered that snapd did not properly restrict writes to the $HOME/bin path in the AppArmor profile for snaps using the home plug. An attacker who could convince a user to install a malicious snap could use this vulnerability to escape the snap sandbox. Zeyad Gouda discovered that snapd failed to properly check the file type when extracting a snap. An attacker who could convince a user to install a malicious snap containing non-regular files could then cause snapd to block indefinitely while trying to read from such files and cause a denial of service.
