CyberSecBulletin
CVE-2022-0556NVD status: Modified

Zyxel AP Configurator (ZAC): Incorrect Permission Assignment for Critical Resource

Published Updated By the CyberSecBulletin desk

CVE-2022-0556 is a high-severity incorrect permission assignment for critical resource vulnerability in Zyxel AP Configurator (ZAC) from Zyxel, with a CVSS 3.1 base score of 7.8 out of 10. It can be exploited with local access to the system by an attacker with a low-privileged account, without any action from a user. Affected Zyxel AP Configurator (ZAC) versions: V1.1.4. The record does not name a fixed version, so check the vendor advisory. There is no confirmed exploitation so far. EPSS estimates a 0.37% chance of exploitation within 30 days, which is low compared with other CVEs.

Next patch cycle

High severity with no evidence of exploitation so far.

What to do

  1. Check which version of Zyxel AP Configurator (ZAC) you run against the affected versions below, and install the vendor's latest release.
  2. Read the advisory on zyxel.com for workarounds and exact fixed builds.

Affected products and versions

VendorProductAffected versionsFixed in
ZyxelZyxel AP Configurator (ZAC)V1.1.4Not stated
ZyxelZyxel Ap Configurator1.1.4Not 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
LocalThe attacker needs local access or must trick a user into running something.
Attack complexity
LowNo special conditions are needed; the attack works reliably.
Privileges required
LowA basic user account is enough.
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:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H. Scored by NVD.

Scoring systemScoreSeverityScored by
CVSS 3.17.3HighCNA (zyxel.com.tw)
CVSS 3.17.8HighNVD
CVSS 2.07.2HighNVD

Official description

A local privilege escalation vulnerability caused by incorrect permission assignment in some directories of the Zyxel AP Configurator (ZAC) version 1.1.4, which could allow an attacker to execute arbitrary code as a local administrator.

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

The underlying weakness: Incorrect Permission Assignment for Critical Resource

The product specifies permissions for a security-critical resource in a way that allows that resource to be read or modified by unintended actors.

How developers prevent this class of flaw

  • When using a critical resource such as a configuration file, check to see if the resource has insecure permissions (such as being modifiable by any regular user), and generate an error or even exit the software if there is a possibility that the resource could have been modified by an unauthorized party.
  • Divide the software into anonymous, normal, privileged, and administrative areas. Reduce the attack surface by carefully defining distinct user groups, privileges, and/or roles. Map these against data, functionality, and the related resources. Then set the permissions accordingly. This will allow you to maintain more fine-grained control over your resources.
  • During program startup, explicitly set the default permissions or umask to the most restrictive setting possible. Also set the appropriate permissions during program installation. This will prevent you from inheriting insecure permissions from any user who installs or runs the program.

More Incorrect Permission Assignment for Critical Resource vulnerabilities (CWE-732)

Timeline

  1. CVE record published.
  2. Record last changed materially (score, affected products, status or references).

References

Recent Incorrect Permission Assignment for Critical Resource vulnerabilities

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