Exploited

CVE-2020-24557

Trend Micro Apex One (ex-OfficeScan) · Security products

Trend Micro Multiple Products Improper Access Control Vulnerability

At a glance

Exploited. Added to CISA’s catalog of exploited vulnerabilities on November 3, 2021.

Affected product: Trend Micro Apex One (ex-OfficeScan) (category Security products, indicative classification). Name in CISA’s catalog: Trend Micro Apex One, OfficeScan, and Worry-Free Business Security.

What should I do?

Apply the security update from Trend Micro.

Deadline set by CISA for US federal agencies: 181 days (due May 3, 2022). It only binds those agencies, but it is a useful measure of urgency.

Trend Micro security advisories page (general page, not the advisory for this vulnerability)
The vendor’s specific advisory is listed in the NVD references: CVE-2020-24557 on the NVD website.

Original text of the required action (CISA)

Apply updates per vendor instructions.

Timeline

September 1, 2020 Vulnerability published Publication date (NVD)
November 3, 2021 Exploitation confirmed Added to CISA’s KEV catalog
May 3, 2022 CISA deadline Remediation deadline set for US federal agencies

The facts, with their sources

Exploitation confirmed: Yes, on November 3, 2021 Date added to the catalog of exploited vulnerabilities. Exploitation itself may have started earlier. Source: KEV catalog, collected September 29, 2026 at 14:57 UTC
Ransomware: No known use to date That does not guarantee it is not being used: the information is not public. Source: KEV catalog, collected September 29, 2026 at 14:57 UTC
Hunt for compromise: Not requested by CISA Source: KEV catalog, collected September 29, 2026 at 14:57 UTC
CISA required action: Apply the security update from Trend Micro. Rewritten by this site from CISA’s original text. Source: KEV catalog, collected September 29, 2026 at 14:57 UTC
CISA deadline: May 3, 2022, 181 days Set for US federal agencies: a measure of urgency, not an obligation elsewhere. Source: KEV catalog, collected September 29, 2026 at 14:57 UTC
Vulnerability published: September 1, 2020 Source: National Vulnerability Database (NVD), collected September 29, 2026 at 15:00 UTC
Product according to CISA: Trend Micro Apex One, OfficeScan, and Worry-Free Business Security Filed by this site under “Security products” (indicative classification). Source: KEV catalog, collected September 29, 2026 at 14:57 UTC
CVSS vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H Technical detail of the score: attack vector, complexity, impact. Source: National Vulnerability Database (NVD), collected September 29, 2026 at 15:00 UTC

Severity and activity

7.8 / 10 CVSS severity: high

Score from the NVD. Collected Sep 29, 2026.

— Probability of exploitation in the next 30 days (EPSS)

FIRST’s EPSS model. Since exploitation is already confirmed, this figure is mostly useful to compare activity. Collected Sep 29, 2026.

Description

A vulnerability in Trend Micro Apex One and Worry-Free Business Security 10.0 SP1 on Microsoft Windows may allow an attacker to manipulate a particular product folder to disable the security temporarily, abuse a specific Windows function and attain privilege escalation. An attacker must first obtain the ability to execute low-privileged code on the target system in order to exploit this vulnerability. Please note that version 1909 (OS Build 18363.719) of Microsoft Windows 10 mitigates hard links, but previous versions are affected.

Trend Micro Apex One, OfficeScan, and Worry-Free Business Security on Microsoft Windows contain an improper access control vulnerability that may allow an attacker to manipulate a particular product folder to disable the security temporarily, abuse a specific Windows function, and attain privilege escalation.

Summary from CISA (KEV catalog).

CERT-FR advisories

No advisory among the latest CERT-FR publications this site follows. That does not mean there are none.

Information reused under the Open Licence 2.0 (Etalab); the date of last update is shown for each advisory. This site is neither affiliated with nor endorsed by ANSSI.

Sources for this page

CISA KEV catalog: exploitation, date added, required action, deadline, ransomware.
NVD (NIST): CVSS severity, publication date, description, vendor references.
EPSS (FIRST): probability of exploitation.
CERT-FR: advisories and alerts (in French).
Brand and category: indicative classification by this site (method).