CVE-2020-8903 in Google and OpenSuse Products
Published on June 22, 2020
Priviged Escalation in Google Cloud Platform's Guest-OSLogin
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.
Weakness Type
Incorrect Default Permissions
During installation, installed file permissions are set to allow anyone to modify those files.
Products Associated with CVE-2020-8903
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Affected Versions
Google LLC guest-oslogin:- Version 20190304 and below 20200507 is affected.
- Version 20200507 is unaffected.
Exploit Probability
EPSS
0.09%
Percentile
25.80%
EPSS (Exploit Prediction Scoring System) scores estimate the probability that a vulnerability will be exploited in the wild within the next 30 days. The percentile shows you how this score compares to all other vulnerabilities.