CyberSecBulletin
CVE-2022-43946NVD status: Modified

FortiClientWindows: Time-of-check Time-of-use (TOCTOU) Race Condition

Published Updated By the CyberSecBulletin desk

CVE-2022-43946 is a high-severity time-of-check time-of-use (TOCTOU) race condition vulnerability in FortiClientWindows from Fortinet, with a CVSS 3.1 base score of 8.1 out of 10. It can be exploited remotely over the network by an unauthenticated attacker, without any action from a user. Affected FortiClientWindows versions: 7.0.0 through 7.0.7; 6.4.0 through 6.4.10; 6.2.0 through 6.2.9, and others listed below. The record does not name a fixed version, so check the vendor advisory. There is no confirmed exploitation so far. EPSS estimates a 0.7% chance of exploitation within 30 days, higher than 54% of scored CVEs.

Next patch cycle

High severity with no evidence of exploitation so far.

What to do

  1. Update Forticlient to 7.0.8 or a later version.
  2. Read the advisory on fortiguard.com for workarounds and exact fixed builds.
  3. Until you can update, restrict network access to the affected service so it is not reachable from untrusted networks.

Affected products and versions

VendorProductAffected versionsFixed in
FortinetFortiClientWindows7.0.0 through 7.0.7; 6.4.0 through 6.4.10; 6.2.0 through 6.2.9; 6.0.0 through 6.0.10Not stated
FortinetForticlient6.0.0 up to, but not including, 7.0.87.0.8

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
NetworkCan be exploited remotely over a network, including the internet.
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:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H. Scored by NVD.

Scoring systemScoreSeverityScored by
CVSS 3.17.5HighCNA (fortinet.com)
CVSS 3.18.1HighNVD

Official description

Multiple vulnerabilities including an incorrect permission assignment for critical resource [CWE-732] vulnerability and a time-of-check time-of-use (TOCTOU) race condition [CWE-367] vulnerability in Fortinet FortiClientWindows before 7.0.7 allows attackers on the same file sharing network to execute commands via writing data into a windows pipe.

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

The underlying weakness: Time-of-check Time-of-use (TOCTOU) Race Condition

The product checks the state of a resource before using that resource, but the resource's state can change between the check and the use in a way that invalidates the results of the check.

How developers prevent this class of flaw

  • The most basic advice for TOCTOU vulnerabilities is to not perform a check before the use. This does not resolve the underlying issue of the execution of a function on a resource whose state and identity cannot be assured, but it does help to limit the false sense of security given by the check.
  • When the file being altered is owned by the current user and group, set the effective gid and uid to that of the current user and group when executing this statement.
  • Limit the interleaving of operations on files from multiple processes.

More Time-of-check Time-of-use (TOCTOU) Race Condition vulnerabilities (CWE-367)

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

Other vulnerabilities in FortiClientWindows

All FortiClientWindows vulnerabilities

Recent Time-of-check Time-of-use (TOCTOU) Race Condition vulnerabilities

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