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Threats / Trend Micro / CVE-2020-24557
CVE-2020-24557 · EUVD no mirror located · GCVE no mirror located Verified 2026-08-04

Trend Micro Apex One, OfficeScan, and Worry-Free Business Se vulnerability

Improper access control in Trend Micro Apex One, OfficeScan, and Worry-Free Business Security allows attackers to manipulate product folders, disable security, and escalate privileges on Windows systems.

Verdict

Today item — known-exploited.

A local privilege escalation vulnerability affecting multiple Trend Micro endpoint security products. Attackers exploit improper access controls to temporarily disable security protections and gain elevated system privileges through Windows function abuse.

CISA KEV Yes · 2021-11-034EPSS 0.02639 (verify live)5CVSS 7.8 (CISA)3CISA SSVC Exploitation: active · Automatable: no · Impact: total3
01

Is it exploitable?

— the evidence, ranked above the score
Reported exploitation
3 independent public reports of in-the-wild exploitation are cataloged.Distinct reporting sources (vendor, incident response, government); open them for the underlying claims.
jpcert.or.jp ↗therecord.media ↗cisa.gov ↗Confirmed
Exploited in the wild
Listed in the CISA Known Exploited Vulnerabilities catalog (added 2021-11-03).
CISA KEV ↗Confirmed
Probability (EPSS)
EPSS 0.02639 — modeled likelihood of exploitation activity.EPSS is a daily-changing model output — open the source for today's value.
FIRST EPSS ↗High
Severity / affected
CVSS 7.8 (CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H) · Affected: Trend Micro, Apex One, OfficeScan, and Worry-Free Business Security. Confirm exact fixed builds in the vendor advisory.CVSS — CISA-assigned via the ADP container (CVE.org), version 3.1; the CNA left no metrics, so CISA's own score is used ahead of NVD.
CISA-ADP ↗Reported
CISA SSVC (triage disposition)
Exploitation: active · Automatable: no · Technical Impact: totalCISA's own stakeholder-specific triage inputs, published in the CVE record (CISA Coordinator role). NOTE: this is CISA's three decision points; the final Act/Attend/Track decision also requires a Mission & Well-being input not published here, so no overall decision is asserted.
CISA-ADP ↗Reported
Currency of the record
CISA added this to its KEV catalog 428 days after the CVE record was published.KEV lag = CISA-KEV dateAdded − CVE.org datePublished; a floor on how long the known-exploited flaw sat in the public record before the federal catalog listed it. Severity/weakness here is CNA- or CISA-assigned (current at disclosure), independent of NVD's analysis backlog.
CISA KEV ↗CVE.org ↗Reported
02

Who’s exploiting it?

— attribution turns risk into urgency
Attribution not established

No confirmed (advisory-backed) threat-actor attribution is established for this record. Absence of a named actor is not absence of compromise — see Coverage & confidence.

03

Why it matters

— the attack path, told twice: adversary, then board
1

Front door — unauthenticated access narrative 1

Attacker
I identify and access a product folder with insufficient access controls on the target Windows system.
Business
Security software integrity is compromised through unauthorized folder manipulation.
2

Keys to the kingdom — privilege/identity takeover narrative 2

Attacker
I manipulate the product folder contents to disable or bypass active security protections temporarily.
Business
Endpoint protection becomes ineffective, leaving systems exposed to concurrent threats.
3

Lateral reach — past segmentation narrative 3

Attacker
I exploit a specific Windows function while security is disabled to execute code with elevated privileges.
Business
Attacker gains administrative control of the endpoint, enabling lateral movement and data exfiltration.
04

What to do

— defensible action
  • Remediate per the vendor advisory — confirm the fixed build for your version and verify exposure.1
Say it to the boardA vulnerability with this evidence profile is a defensible budget line, not a backlog ticket — fund the change against the proof above.
05

Coverage & confidence

— what we know, and what we don’t

Established (cited)

  • KEV listing (CISA)
  • EPSS probability (FIRST)
  • 3 reported-exploitation source(s)
  • CVSS 7.8 — CISA-assigned (CVE.org ADP)
  • CISA SSVC triage disposition (CVE.org ADP)
  • Catalogued by trendmicro (CNA)

    • Coverage gaps — stated, not hidden

  • No EUVD / GCVE mirror in feed — single-authority dependency for the identifier.
  • EPSS & exposure are time-varying; verify live at the source.
  • Threat-actor attribution not established from feed data — absence of a name is not absence of compromise.
  • No finder/reporter credit recorded in the public CVE entry — the work behind this find is unattributed.
    • Disclosure & credit2
    Catalogued by trendmicroCNA
    Credited with finding itNo finder named in the public CVE record — the work behind this find is unattributed.