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

2020-06-2213:45:25

CWE-276

Google

www.cve.org

7.3 High

CVSS4

Attack Vector

LOCAL

Attack Complexity

HIGH

Privileges Required

LOW

User Interaction

ACTIVE

CVSS:4.0/AV:L/AC:H/AT:N/PR:L/UI:A/VC:H/SC:H/VI:H/SI:H/VA:H/SA:H

7.5 High

AI Score

Confidence

High

0.001 Low

EPSS

Percentile

33.4%

JSON

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.

CNA Affected

[
  {
    "defaultStatus": "unaffected",
    "product": "guest-oslogin",
    "vendor": "Google LLC",
    "versions": [
      {
        "lessThan": "20200507",
        "status": "affected",
        "version": "20190304",
        "versionType": "date"
      },
      {
        "status": "unaffected",
        "version": "20200507",
        "versionType": "date"
      }
    ]
  }
]