CyberSecBulletin
CVE-2023-38744NVD status: Modified

CJ2M CPU Unit: Improper Validation of Specified Quantity in Input

Published Updated By the CyberSecBulletin desk

CVE-2023-38744 is a high-severity improper validation of specified quantity in input vulnerability in CJ2M CPU Unit from Omron, with a CVSS 3.1 base score of 7.5 out of 10. It can be exploited remotely over the network by an unauthenticated attacker, without any action from a user. The record lists version 2.18 as the first without the flaw, so updating CJ2M CPU Unit to that release or later removes the exposure. There is no confirmed exploitation so far. EPSS estimates a 0.87% chance of exploitation within 30 days, higher than 59% of scored CVEs.

Next patch cycle

High severity with no evidence of exploitation so far.

What to do

  1. Update CJ2M CPU Unit to 2.18 or a later version.
  2. Update CJ2H CPU Unit to 3.04 or a later version.
  3. Update CS/CJ Series EtherNet/IP Unit to CS1W-EIP21 V3.04 or CJ1W-EIP21 V3.04, whichever matches your release line, or a later version.
  4. Read the advisory on ia.omron.com for workarounds and exact fixed builds.
  5. 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
OMRONCJ2M CPU Unitbefore 2.182.18
OMRONCJ2H CPU Unitbefore 3.043.04
OMRONCS/CJ Series EtherNet/IP UnitCS1W-EIP21 V3.04 and earlier; CJ1W-EIP21 V3.04 and earlier; before CS1W-EIP21 V3.04; before CJ1W-EIP21 V3.04CS1W-EIP21 V3.04, CJ1W-EIP21 V3.04
OmronCj2m-cpu35 Firmware2.18 and earlierNot stated
OmronCj2m-cpu34 Firmware2.18 and earlierNot stated
OmronCj2m-cpu33 Firmware2.18 and earlierNot stated
OmronCj2m-cpu32 Firmware2.18 and earlierNot stated
OmronCj2m-cpu31 Firmware2.18 and earlierNot stated
OmronCj2h-cpu68-eip Firmware3.04 and earlierNot stated
OmronCj2h-cpu67-eip Firmware3.04 and earlierNot stated
OmronCj2h-cpu66-eip Firmware3.04 and earlierNot stated
OmronCj2h-cpu65-eip Firmware3.04 and earlierNot stated
OmronCj2h-cpu64-eip Firmware3.04 and earlierNot stated
OmronCs1w-eip21 Firmware3.04 and earlierNot stated
OmronCj1w-eip21 Firmware3.04 and earlierNot 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
NetworkCan be exploited remotely over a network, including the internet.
Attack complexity
LowNo special conditions are needed; the attack works reliably.
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
NoneNo data is disclosed.
Integrity
NoneNothing can be modified.
Availability
HighThe component can be taken down completely.

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

Official description

Denial-of-service (DoS) vulnerability due to improper validation of specified type of input issue exists in the built-in EtherNet/IP port of the CJ Series CJ2 CPU unit and the communication function of the CS/CJ Series EtherNet/IP unit. If an affected product receives a packet which is specially crafted by a remote unauthenticated attacker, the unit of the affected product may fall into a denial-of-service (DoS) condition. Affected products/versions are as follows: CJ2M CPU Unit CJ2M-CPU3[] Unit version of the built-in EtherNet/IP section Ver. 2.18 and earlier, CJ2H CPU Unit CJ2H-CPU6[]-EIP Unit version of the built-in EtherNet/IP section Ver. 3.04 and earlier, CS/CJ Series EtherNet/IP Unit CS1W-EIP21 V3.04 and earlier, and CS/CJ Series EtherNet/IP Unit CJ1W-EIP21 V3.04 and earlier.

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

The underlying weakness: Improper Validation of Specified Quantity in Input

The product receives input that is expected to specify a quantity (such as size or length), but it does not validate or incorrectly validates that the quantity has the required properties.

More Improper Validation of Specified Quantity in Input vulnerabilities (CWE-1284)

Timeline

  1. CVE record published.
  2. CISA published its SSVC assessment (exploitation: none, automatable: yes, technical impact: partial).
  3. Record last changed materially (score, affected products, status or references).

References

Third-party and government advisories

Recent Improper Validation of Specified Quantity in Input vulnerabilities

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