Threats / Microsoft / CVE-2017-8540
CVE-2017-8540
· EUVD no mirror located
· GCVE no mirror located
Verified 2026-08-04
Microsoft Malware Protection Engine vulnerability
Microsoft Malware Protection Engine fails to properly scan a specially crafted file, causing memory corruption and enabling remote code execution across Windows and Exchange Server platforms.
Verdict
Today item — known-exploited.
A memory corruption flaw in the Malware Protection Engine allows attackers to execute arbitrary code by crafting malicious files. The vulnerability affects multiple Windows versions and Exchange Server, with active exploitation observed in the wild.
CISA KEV Yes · 2022-03-034EPSS 0.71961 (verify live)5CVSS 7.8 (CISA)3CISA SSVC Exploitation: active · Automatable: no · Impact: total3
01
Is it exploitable?
— the evidence, ranked above the scoreReported exploitation
1 independent public report of in-the-wild exploitation are cataloged.Distinct reporting sources (vendor, incident response, government); open them for the underlying claims.
Exploited in the wild
Listed in the CISA Known Exploited Vulnerabilities catalog (added 2022-03-03).
Probability (EPSS)
EPSS 0.71961 — modeled likelihood of exploitation activity.EPSS is a daily-changing model output — open the source for today's value.
Severity / affected
CVSS 7.8 (CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H) · Affected: Microsoft, Malware Protection Engine. 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.
Weakness (CWE)
Mapped to CWE-119 Memory Buffer Bounds Error — weakness family: Memory safety.CWE assignment from the public NVD record (may be stale); the weakness class drives how the flaw is exploited.
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.
Currency of the record
CISA added this to its KEV catalog 1742 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.
02
Who’s exploiting it?
— attribution turns risk into urgencyAttribution 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 board1
Front door — unauthenticated access narrative 1
Attacker
Craft a specially formatted file designed to trigger improper scanning behavior in the Malware Protection Engine.
Business
Endpoint security controls fail to detect the malicious file, leaving systems unprotected.
2
Keys to the kingdom — privilege/identity takeover narrative 2
Attacker
Deliver the file to a target system running vulnerable versions of Windows or Exchange Server.
Business
The file reaches protected infrastructure without being blocked by antimalware defenses.
3
Lateral reach — past segmentation narrative 3
Attacker
Trigger memory corruption within the Engine process during file scanning.
Business
Memory safety violations create exploitable conditions within a privileged security process.
4
Data at risk — exfiltration narrative 4
Attacker
Execute arbitrary code with the privileges of the Malware Protection Engine.
Business
Attackers gain code execution on systems intended to be protected, potentially compromising servers and workstations.
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