CVE-2020-8903 Detail

Current 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.


View Analysis Description

Severity



CVSS 3.x Severity and Metrics:

NIST CVSS score
NIST: NVD
Base Score:  7.8 HIGH
Vector:  CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Nist CVSS score does not match with CNA score
CNA:  Google Inc.
Base Score:  6.7 MEDIUM
Vector:  CVSS:3.1/AV:L/AC:H/PR:L/UI:R/S:U/C:H/I:H/A:H


NVD Analysts use publicly available information to associate vector strings and CVSS scores. We also display any CVSS information provided within the CVE List from the CNA.

Note: It is possible that the NVD CVSS may not match that of the CNA. The most common reason for this is that publicly available information does not provide sufficient detail or that information simply was not available at the time the CVSS vector string was assigned.

References to Advisories, Solutions, and Tools

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Hyperlink Resource
http://lists.opensuse.org/opensuse-security-announce/2020-07/msg00037.html
http://lists.opensuse.org/opensuse-security-announce/2020-07/msg00047.html
https://cloud.google.com/support/bulletins/#gcp-2020-008 Vendor Advisory 
https://github.com/GoogleCloudPlatform/guest-oslogin/pull/29 Patch  Third Party Advisory 
https://gitlab.com/gitlab-com/gl-security/gl-redteam/red-team-tech-notes/-/tree/master/oslogin-privesc-june-2020 Exploit  Third Party Advisory 

Weakness Enumeration

CWE-ID CWE Name Source
CWE-276 Incorrect Default Permissions cwe source acceptance level NIST   Reference acceptance level Google Inc.  

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Change History

3 change records found show changes

Quick Info

CVE Dictionary Entry:
CVE-2020-8903
NVD Published Date:
06/22/2020
NVD Last Modified:
07/19/2020
Source:
Google Inc.