CVE-2023-39341Network attack vector

Security-engine suspension via mishandled Defender event

Published Aug 9, 2023 · Updated Oct 17, 2024

Denial of service in FFRI yarai 3.4.0 through 3.4.6 and 3.5.0 allows attackers to suspend endpoint monitoring via a crafted file. The Windows Defender integration mishandles threat information for certain files and stops the Scan Engine Service for up to 15 minutes. The same flaw affects listed OEM releases; Defender integration must be enabled and a user must open a file that Microsoft Defender detects, while Defender itself remains active.

CVSS severity4.3
Medium
EPSS probability0.29%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Denial of service in FFRI yarai 3.4.0 through 3.4.6 and 3.5.0 allows attackers to suspend endpoint monitoring via a crafted file. The Windows Defender integration mishandles threat information for certain files and stops the Scan Engine Service for up to 15 minutes. The same flaw affects listed OEM releases; Defender integration must be enabled and a user must open a file that Microsoft Defender detects, while Defender itself remains active.

The record

CVE
CVE-2023-39341
Published
Aug 9, 2023
Updated
Oct 17, 2024
Vendor
Sky Co., Ltd.
Product
SKYSEA Client View EDR Plus Pack
Classifications
CWE-703, CWE-755, T1562.001
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Aug 9, 2023CVE publishedPublication date reported by the CVE source.
  2. Oct 17, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=Bundled FFRI yarai versions 3.4.0 to 3.4.6 and 3.5.0

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Sky Co., Ltd. · SKYSEA Client View EDR Plus Packversion=Bundled FFRI yarai versions 3.4.0 to 3.4.6 and 3.5.0
Soliton Systems K.K. · InfoTrace Mark II Malware Protection (Mark II Zerona)version=versions 3.0.1 to 3.2.2
FFRI Security, Inc. · FFRI yaraiversion=versions 3.4.0 to 3.4.6 and 3.5.0
NEC Corporation · ActSecure χversion=versions 3.4.0 to 3.4.6 and 3.5.0
FFRI Security, Inc. · FFRI yarai Home and Business Editionversion=version 1.4.0
Sky Co., Ltd. · SKYSEA Client View EDR Plus Pack Cloudversion=Bundled FFRI yarai versions 3.4.0 to 3.4.6 and 3.5.0
Sourcenext Corporation · Dual Safe Powered by FFRI yaraiversion=version 1.4.1
Soliton Systems K.K. · Zerona / Zerona PLUSversion=versions 3.2.32 to 3.2.36

Published CVSS scores

4.3JPCERT/CC JVNAV:N/AC:M/Au:N/C:N/I:N/A:P
3.3NIST NVDCVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:L
4.3JPCERT/CC JVNCVSS:3.0/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:L

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-703Improper Check or Handling of Exceptional Conditions
CWE-755Improper Handling of Exceptional Conditions
T1562.001Impair Defenses: Disable or Modify Tools

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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