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CVE-2023-20867VMware Tools Authentication Bypass Vulnerability

Patch nowLow3.9Exploited, CISA due date 2023-07-14EPSS 14%, higher than 97% of scored CVEs

CVE-2023-20867 is a improper authentication in VMware Tools, rated low (3.9 on CVSS 3.1).

Why this priority: Exploited in the wild: listed in CISA's KEV catalog.

Published · Updated · NVD status: Analyzed

What it is

The software does not prove who a caller is, so an attacker can pass as someone else.

How it is reached

An attacker can exploit it by someone who can already run code or sign in on the machine, with an administrator account, and nobody has to click anything. Success also depends on conditions the attacker does not fully control.

What an attacker gains

The direct impact is limited: partial access to data or a partial outage. In practice, this kind of flaw lets an attacker act as a signed-in user, or an administrator, without valid credentials. The damage can spread past the vulnerable component into others.

Is it being exploited?

CISA added it to the Known Exploited Vulnerabilities catalog on 2023-06-23: it is being exploited in the wild. EPSS estimates a 14% chance of exploitation activity in the next 30 days, higher than 97% of scored CVEs.

What to do

  1. Treat it as urgent: it is on CISA's KEV list. CISA's deadline for US federal agencies: 2023-07-14.
  2. Upgrade VMware Tools to 12.2.5 or later. The patch notes are linked below.
  3. Limit who can run code or sign in on the hosts that run it.
  4. Check exposed instances for signs of compromise, not only for the version.

Description from NVD

A fully compromised ESXi host can force VMware Tools to fail to authenticate host-to-guest operations, impacting the confidentiality and integrity of the guest virtual machine.

What this means for your architecture.

A CVE names a product. Whether it matters depends on where that product sits in your systems: what reaches it, which trust boundary it guards and what it can reach once compromised. Veriom maps your components, their relationships and your trust boundaries from your code, cloud and delivery evidence, so you can see where a component like this sits. The radar itself does not look at your systems.

Components it touches

  • Operating systems on servers, workstations or devices. Everything on the host inherits the flaw.
  • Sign-in, session and token handling. The flaw sits between anonymous callers and authenticated sessions.
  • Identity providers and SSO. The flaw sits between anonymous callers and authenticated sessions.

Trust boundaries in play

  • Host boundary. The attacker needs a foothold on the machine first; the flaw turns a small foothold into a bigger one.
  • Isolation between components. The impact crosses out of the vulnerable component into others it should be isolated from.
  • Between anonymous callers and authenticated sessions. An attacker who crosses it can act as a signed-in user, or an administrator, without valid credentials.

Questions to answer about your own systems

  • Where does VMware Tools run in your systems, and at which version?
  • Which of those hosts also run code or users you do not fully trust?
  • What can it reach once compromised: which data stores, secrets and services?
See how Veriom maps an architectureTake the interactive tour

Read more

Sources

  • CVE records and CVSS scores from the NVD CVE API. This product uses the NVD API but is not endorsed or certified by the NVD.
  • Exploitation status from CISA’s Known Exploited Vulnerabilities catalog.
  • Exploit likelihood from FIRST’s Exploit Prediction Scoring System (EPSS), refreshed daily.
  • Explanations are written by Veriom from fixed templates over each record’s data, not by a person reviewing each CVE. Descriptions are quoted from the records as published.