CyberSecBulletin
CVE-2023-20900NVD status: Modified

VMware Tools: Authentication Bypass by Capture-replay

Published Updated By the CyberSecBulletin desk

CVE-2023-20900 is a high-severity authentication bypass by capture-replay vulnerability in VMware Tools, with a CVSS 3.1 base score of 7.5 out of 10. It can be exploited from the same local network by an unauthenticated attacker, without any action from a user. Affected VMware Tools versions: 12.x.x; 11.x.x; 10.3.x. The record does not name a fixed version, so check the vendor advisory. There is no confirmed exploitation so far. EPSS estimates a 1.47% chance of exploitation within 30 days, higher than 74% of scored CVEs.

Next patch cycle

High severity with no evidence of exploitation so far.

What to do

  1. Update Tools to 12.3.0 or 10.3.26, whichever matches your release line, or a later version.
  2. Update Open VM Tools to 12.3.0 or a later version.
  3. Read the advisory on vmware.com for workarounds and exact fixed builds.

Affected products and versions

VendorProductAffected versionsFixed in
VMware ToolsVMware Tools12.x.x; 11.x.x; 10.3.xNot stated
VMware Tools (open-vm-tools)VMware Tools (open-vm-tools)12.x.x; 11.x.x; 10.3.xNot stated
VMwareTools10.3.0 up to, but not including, 12.3.0; 10.3.0 up to, but not including, 10.3.2612.3.0, 10.3.26
VMwareOpen VM Tools10.3.0 up to, but not including, 12.3.012.3.0
Fedora ProjectFedora37; 38; 39Not stated
DebianDebian Linux10.0; 11.0; 12.0Not stated
NetAppOntap Select Deploy Administration UtilityNot specified in the recordNot stated

Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.

How the severity score breaks down

Attack vector
AdjacentThe attacker must be on the same local network segment.
Attack complexity
HighSuccess depends on conditions outside the attacker's control.
Privileges required
NoneNo account or login is needed.
User interaction
NoneNo action by a victim is required.
Scope
UnchangedImpact stays within the vulnerable component.
Confidentiality
HighAll data handled by the component can be read.
Integrity
HighData or code can be modified at will.
Availability
HighThe component can be taken down completely.

Vector: CVSS:3.1/AV:A/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H. Scored by NVD.

Scoring systemScoreSeverityScored by
CVSS 3.17.1HighCNA (vmware.com)
CVSS 3.17.5HighNVD

Official description

A malicious actor that has been granted Guest Operation Privileges https://docs.vmware.com/en/VMware-vSphere/8.0/vsphere-security/GUID-6A952214-0E5E-4CCF-9D2A-90948FF643EC.html in a target virtual machine may be able to elevate their privileges if that target virtual machine has been assigned a more privileged Guest Alias https://vdc-download.vmware.com/vmwb-repository/dcr-public/d1902b0e-d479-46bf-8ac9-cee0e31e8ec0/07ce8dbd-db48-4261-9b8f-c6d3ad8ba472/vim.vm.guest.AliasManager.html .

Source: the CVE record as published by its numbering authority, via NVD and CVE.org.

The underlying weakness: Authentication Bypass by Capture-replay

A capture-replay flaw exists when the design of the product makes it possible for a malicious user to sniff network traffic and bypass authentication by replaying it to the server in question to the same effect as the original message (or with minor changes).

How developers prevent this class of flaw

  • Utilize some sequence or time stamping functionality along with a checksum which takes this into account in order to ensure that messages can be parsed only once.
  • Since any attacker who can listen to traffic can see sequence numbers, it is necessary to sign messages with some kind of cryptography to ensure that sequence numbers are not simply doctored along with content.

More Authentication Bypass by Capture-replay vulnerabilities (CWE-294)

Timeline

  1. CVE record published.
  2. CISA published its SSVC assessment (exploitation: none, automatable: no, technical impact: total).
  3. Record last changed materially (score, affected products, status or references).

References

Patches and release notes

Third-party and government advisories

Other vulnerabilities in VMware Tools

All VMware Tools vulnerabilities

Recent Authentication Bypass by Capture-replay vulnerabilities

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