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GHSA-g8qw-mgjx-rwjr
No affected components available
Impact
When an authd user logs in via SSH for the first time (meaning they do not yet exist in the authd user database) and successfully authenticates via the configured broker, the user is considered a member of the root group in the context of that SSH session. This situation may allow the user to read and write files that are accessible by the root group, to which they should not have access. The user does not get root privileges or any capabilities beyond the access granted to the root group.
Preconditions under which this vulnerability affects a system
- authd was installed via the PPA.
- An OAuth 2.0 application was registered in Microsoft Entra ID or Google IAM, and the respective authd broker was installed (authd-msentraid or authd-google) and configured.
- sshd was configured to enable SSH access with authd, i.e.:
UsePAM yes KbdInteractiveAuthentication yes - The username is allowed by the
ssh_allowed_suffixesoption in the broker configuriation. - The user is allowed by the
allowed_usersoption in the broker configuration. - The user successfully authenticates via the authd broker (Entra ID or Google IAM).
- The user did not log in locally before.
Patches
Fixed by https://github.com/ubuntu/authd/commit/619ce8e55953b970f1765ddaad565081538151ab
Workarounds
Configure the SSH server to not allow authenticating via authd, for example by setting UsePAM no or KbdInteractiveAuthentication no in the sshd_config (see https://documentation.ubuntu.com/authd/stable/howto/login-ssh/#ssh-configuration).
The vulnerability can be exploited over the network without needing physical access. It is easy for an attacker to exploit this vulnerability. An attacker needs basic access or low-level privileges. No user interaction is needed for the attacker to exploit this vulnerability. The vulnerability can affect other systems as well, not just the initial system. There is a low impact on the confidentiality of the information. There is a low impact on the integrity of the data.
Exploitation attempts have been detected. Elevated vigilance and prompt remediation are advised.
The exploit probability is very low. The vulnerability is unlikely to be exploited in the next 30 days.
We did not find any exploit available. Neither in GitHub repositories nor in the Exploit-Database.
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