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Vulnerability · Published Jun 22, 2020 · Assigned by Google

CVE-2020-8903Priviged Escalation in Google Cloud Platform's Guest-OSLogin

High 7.3

In plain English

A high-severity incorrect default permissions in guest-oslogin from Google LLC. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.3% (higher than 25% of all known vulnerabilities).

Severity (CVSS 4.0)7.3High
Exploit odds (30 days)0.3%top 75.4% of all CVEs
Exploited in the wildNo reportsnot in CISA KEV
Attack toolingNoneno public tooling known

Official description

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.

Affected products (as reported)

VendorProductVersions
Google LLC guest-oslogin 20190304 – before 20200507

Weakness: CWE-276 · Vector: 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

References