Описание
CVE-2024-5138: snapd snapctl auth bypass
Impact
A snap with prior permissions to create a mount entry on the host, such as firefox, normally uses the permission from one of the per-snap hook programs. A unprivileged users cannot normally trigger that behaviour by using snap run --shell firefox followed by snapctl mount, since snapd validates the requesting user identity (root or non-root). The issue allows unprivileged users to bypass that check by crafting a malicious command line vector which confuses snapd into thinking the help message is requested.
Unprivileged user on a default installation of Ubuntu, where firefox is as provided as a snap, may cause a denial-of-service attack by repeatedly mounting hunspell database over and over and eventually exhausting system memory.
Other attacks, reliant on the same underying mechanism (mount), are possible. In all cases the snap must be installed and grated permission to perform this action (by connecting an appropriate snap interface), which requires administrative privileges. As such we are focusing on the case of default installation where an unprivileged user may exploit this behavior.
Patches
Patch: https://github.com/canonical/snapd/commit/68ee9c6aa916ab87dbfd9a26030690f2cabf1e14 Release: Available from Snapd 2.64
Workarounds
Users may disconnect any instances of the mount-control interface to prevent snapd from creating such mount points. For example, the firefox snap has the host-hunspell plug, which is of type mount-control. The interface can be disconnected with:
References
The original bug report was made on Launchpad: https://bugs.launchpad.net/snapd/+bug/2065077 CVE.org: https://www.cve.org/CVERecord?id=CVE-2024-5138 Canonical: https://ubuntu.com/security/CVE-2024-5138
Пакеты
github.com/snapcore/snapd
>= 2.51.6, < 2.63.1
2.63.1
github.com/snapcore/snapd
< 0.0.0-20240524114846-68ee9c6aa916
0.0.0-20240524114846-68ee9c6aa916
Связанные уязвимости
The snapctl component within snapd allows a confined snap to interact with the snapd daemon to take certain privileged actions on behalf of the snap. It was found that snapctl did not properly parse command-line arguments, allowing an unprivileged user to trigger an authorised action on behalf of the snap that would normally require administrator privileges to perform. This could possibly allow an unprivileged user to perform a denial of service or similar.
The snapctl component within snapd allows a confined snap to interact with the snapd daemon to take certain privileged actions on behalf of the snap. It was found that snapctl did not properly parse command-line arguments, allowing an unprivileged user to trigger an authorised action on behalf of the snap that would normally require administrator privileges to perform. This could possibly allow an unprivileged user to perform a denial of service or similar.
The snapctl component within snapd allows a confined snap to interact ...
Уязвимость компонента snapctl утилиты для управления самодостаточными пакетами snapd, связанная с неправильной проверкой входных данных, позволяющая нарушителю повысить свои привилегии
