Priviged Escalation in Google Cloud Platform's Guest-OSLogin
21Vexday Risk Score
No sign of exploitation. No public exploitation artifact known so far.
ssvc Trackcvss 7.3epss 0.3%
exploitation probability
0.3%top 75% of all CVEs
observed exploitation
nono source reports it
A vulnerability in Google Cloud Platform's guest-oslogin versions between 20190304 and 20200507 allows a user that is only granted the role "roles/compute.osLogin" to escalate privileges to root. Using their membership to the "adm" group, users with this role are able to read the DHCP XID from the systemd journal. Using the DHCP XID, it is then possible to set the IP address and hostname of the instance to any value, which is then stored in /etc/hosts. An attacker can then point metadata.google.internal to an arbitrary IP address and impersonate the GCE metadata server which make it is possible to instruct the OS Login PAM module to grant administrative privileges. All images created after 2020-May-07 (20200507) are fixed, and if you cannot update, we recommend you edit /etc/group/security.conf and remove the "adm" user from the OS Login entry.
CVSS:4.0/AV:L/AC:H/AT:N/PR:L/UI:A/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H
Affected products
Google LLC · guest-osloginReferences
http://lists.opensuse.org/opensuse-security-announce/2020-07/msg00037.htmlhttp://lists.opensuse.org/opensuse-security-announce/2020-07/msg00047.htmlhttps://cloud.google.com/support/bulletins/#gcp-2020-008https://github.com/GoogleCloudPlatform/guest-oslogin/pull/29https://gitlab.com/gitlab-com/gl-security/gl-redteam/red-team-tech-notes/-/tree/master/oslogin-privesc-june-2020