CriticalCVE-2023-24880

Windows SmartScreen Security Feature Bypass Vulnerability (CVE-2023-24880)

Published 14.03.2023In CISA KEV since 14.03.2023Sources: pwn.watch, CVE.org

What is affected, what to do

Windows SmartScreen Security Feature Bypass Vulnerability

The vulnerability is being actively exploited; treat it as a priority. CISA lists it as used in ransomware campaigns. Update Microsoft Windows 10 Version 1809 to version 10.0.17763.4131, Microsoft Windows Server 2019 to version 10.0.17763.4131, Microsoft Windows Server 2019 (Server Core installation) to version 10.0.17763.4131. Immediate actions, mitigation and detection rules are in the runbook below.

Affected: Microsoft Windows 10 Version 1809 lt 10.0.17763.0..10.0.17763.4131
Microsoft Windows Server 2019 lt 10.0.17763.0..10.0.17763.4131
Microsoft Windows Server 2019 (Server Core installation) lt 10.0.17763.0..10.0.17763.4131
Microsoft Windows Server 2022 lt 10.0.20348.0..10.0.20348.1607
Microsoft Windows 10 Version 20H2 lt 10.0.0..10.0.19042.2728
Microsoft Windows 11 version 21H2 lt 10.0.0..10.0.22000.1696
Microsoft Windows 10 Version 21H2 lt 10.0.19043.0..10.0.19044.2728
Microsoft Windows 11 version 22H2 lt 10.0.22621.0..10.0.22621.1413
Microsoft Windows 10 Version 22H2 lt 10.0.19045.0..10.0.19045.2728
Microsoft Windows 10 Version 1607 lt 10.0.14393.0..10.0.14393.5786
Microsoft Windows Server 2016 lt 10.0.14393.0..10.0.14393.5786
Microsoft Windows Server 2016 (Server Core installation) lt 10.0.14393.0..10.0.14393.5786
Fixed in: Microsoft Windows 10 Version 1809 10.0.17763.4131
Microsoft Windows Server 2019 10.0.17763.4131
Microsoft Windows Server 2019 (Server Core installation) 10.0.17763.4131
Microsoft Windows Server 2022 10.0.20348.1607
Microsoft Windows 10 Version 20H2 10.0.19042.2728
Microsoft Windows 11 version 21H2 10.0.22000.1696
Microsoft Windows 10 Version 21H2 10.0.19044.2728
Microsoft Windows 11 version 22H2 10.0.22621.1413
Microsoft Windows 10 Version 22H2 10.0.19045.2728
Microsoft Windows 10 Version 1607 10.0.14393.5786
Microsoft Windows Server 2016 10.0.14393.5786
Microsoft Windows Server 2016 (Server Core installation) 10.0.14393.5786

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Metrics

4.4

Priority

XIEM Effective CVSS: highest available CVSS rating from NVD and vendor data.

Source: NVD, CVSS v3

4.4

CVSS v3

Severity Medium on the scale from 0 to 10.

Source: pwn.watch, CVE.org

78.0 %

EPSS score

High — model estimates ≥ 50% chance of real-world exploitation within 30 days.

Source: FIRST EPSS, percentile 99.57

Show all metrics

Severity: Critical
Priority (0–325) The priority score is a consolidated metric that condenses several individual signals into a single, action-guiding ranking: technical severity (CVSS), exploitation likelihood (EPSS), known-exploited status (KEV) and the context of the affected asset. The aim is to answer the only truly important question in vulnerability management: what first? Read in glossary: 228.64 Methodology
Exploit maturity An exploit is code or a technique that specifically uses a concrete vulnerability to force unintended behaviour — such as executing code or escalating privileges. It is the tool that turns a theoretical flaw into a practical attack. Read in glossary: actively exploited
XIEM Effective CVSS XIEM® is the tiered managed-security operating model from NEOSEC and a registered trademark of NEOSEC GmbH. It extends classic SIEM — the central collection, normalisation and correlation of security-relevant events — with endpoint forensics, network visibility and deception technology, and consolidates them into three building tiers: Sentry, Orchestrate and Command. Read in glossary: 4.4 Methodology
CVSS v3 CVSS is the globally established, open standard for assessing the technical severity of a vulnerability on a scale from 0 to 10. It describes how easily a flaw can be exploited and what damage it can cause — but not how likely its actual exploitation is. CVSS and the complementary EPSS deliberately answer different questions. Read in glossary: 4.4
EPSS score The EPSS score is the absolute model output for an individual vulnerability: the estimated probability of real-world exploitation within the next 30 days, expressed as a value between 0 and 1 (i.e. 0 % to 100 %). A score of 0.42 means „the model estimates a 42 % chance of real-world exploitation within 30 days“. Read in glossary: 78.0 %; High — model estimates ≥ 50% chance of real-world exploitation within 30 days.
EPSS percentile The EPSS percentile is the relative position of a vulnerability within all EPSS-scored CVEs, expressed as a value between 0 and 1. A percentile of 0.90 means „this CVE has a higher EPSS score than 90 % of all other scored CVEs“. Unlike the EPSS score, it is not a probability — but a positioning within a ranking. Read in glossary: 99.57; Critical — this CVE ranks in the top fifth of all CVEs scored today (rank ≥ 80%).
KEV status The KEV catalogue is a list maintained by the US authority CISA of vulnerabilities for which active exploitation in the wild has been confirmed. It answers not the question „how severe?“ but „is it already being attacked?“ — thereby sharply prioritising patching. Read in glossary: Actively exploited
Published: 14.03.2023
In CISA KEV since The KEV catalogue is a list maintained by the US authority CISA of vulnerabilities for which active exploitation in the wild has been confirmed. It answers not the question „how severe?“ but „is it already being attacked?“ — thereby sharply prioritising patching. Read in glossary: 14.03.2023
CISA assessment (SSVC): Exploitation: active · not automatable · Technical impact: partial; Source: CISA Vulnrichment, as of 22 December 2023
CWE CWE is a catalogue of typical weakness types in software and hardware — such as flawed input validation, unsafe memory handling or poor authentication. Where a CVE names a concrete vulnerability in a concrete product, a CWE describes the underlying class of defect. Read in glossary: CWE-863

Response and mitigation

Why act now?

Prioritisation rationale

The low base severity is misleading. Exploitation requires local execution and user interaction, but the flaw disables the exact control meant to stop phishing and drive-by downloads that pose as software updates. That is why it appears in campaigns CISA explicitly flags as ransomware-related, and it ranks among the CVEs most likely to be exploited. Any organisation with internet-connected Windows workstations should treat it as high priority: patch within the emergency window, and keep the MSI hardening in place permanently, because MOTW bypasses keep recurring.

01
Runbook step 1
Immediate response (0-24 h)
- Deploy Microsoft's March 2023 security update (Patch Tuesday, 2023-03-14) to all affected clients and servers. Target builds per context:
  
  Windows 10 1607/Server 2016: 10.0.14393.5786 or later
  
  Windows 10 1809: 10.0.17763.4131 or later
  
  Windows 10 20H2: 10.0.19042.2728 or later
  
  Windows 10 21H2: 10.0.19044.2728 or later
  
  Windows 10 22H2: 10.0.19045.2728 or later
  
  Windows 11 21H2: 10.0.22000.1696 or later
  
  Windows 11 22H2: the build given in the context is ambiguous. Look up the exact KB in the vendor advisory (MSRC CVE-2023-24880).
- Verify patch compliance via Intune, SCCM/MECM or WSUS. Prioritise unpatched endpoints whose users have internet and email access, especially office, sales and finance workstations.
- Temporarily block or quarantine external MSI files, and archives containing MSIs, at the mail gateway and web proxy.
- Retro-hunt for MSI packages installed from download or browser-cache paths since mid-March 2023 (see Detection rules). Isolate and image any hits.
- Warn users that the absence of a SmartScreen prompt on downloaded "updates" (fake browser or security updates) does not mean the file is safe.
02
Runbook step 2
Mitigation layers
- Configuration (GPO): Set "Computer Configuration > Administrative Templates > Windows Components > Windows Installer > Turn off Windows Installer" to "For non-managed applications only" (DisableMSI=1). Also enable "Prohibit User Installs". This stops standard users from running arbitrary MSIs.
- Endpoint hardening: Enable the Defender ASR rule "Block executable files from running unless they meet a prevalence, age, or trusted list criterion" (GUID 01443614-cd74-433a-b99e-2ecdc07bfc25). Run it in audit mode first, then switch to block. It works independently of SmartScreen and Mark of the Web (MOTW).
- Application control: Use WDAC or AppLocker to restrict msiexec.exe installs to packages signed by trusted publishers and to software-distribution paths. Exclude %USERPROFILE%\Downloads and %TEMP%.
- IAM/least privilege: Remove local admin rights using LAPS or Windows LAPS plus just-in-time elevation. Ransomware follow-on stages often fail without elevation.
- Network/proxy: Block downloads of .msi, .msix and .appx from uncategorised or newly registered domains. File-type filtering requires TLS inspection.
03
Runbook step 3
Detection rules
- EDR/KQL: Hunt for msiexec launching packages from download paths or URLs: DeviceProcessEvents | where FileName =~ "msiexec.exe" and ProcessCommandLine has_any ("\\Downloads\\","\\INetCache\\","http") | where InitiatingProcessFileName in~ ("explorer.exe","msedge.exe","chrome.exe","firefox.exe")
- Sysmon EID 15 (FileCreateStreamHash): Capture Zone.Identifier streams with ZoneId=3 on .msi files. Correlate them with Sysmon EID 1 where msiexec.exe runs the same file. If no SmartScreen warn or block event follows, treat it as a suspected bypass.
- Windows Application log: Review source MsiInstaller, Event ID 1040/1042 (transaction start/end) and 11707/1033 (install completed), for packages outside your software-distribution channel. Splunk starting point: index=wineventlog source="WinEventLog:Application" SourceName=MsiInstaller EventCode IN (1033,11707) | stats count by host, Message
- Signature anomaly: Use an EDR file scan or YARA to find MSI files in user profiles with malformed or unverifiable Authenticode signatures. Malformed signatures are the core trait of this bypass technique.
- Process chain: Treat msiexec.exe → cmd.exe/powershell.exe/rundll32.exe, followed by mass file access or vssadmin delete shadows, as a high-severity Sigma correlation.

Detection rules

No NEOSEC detection rule is available for this vulnerability yet.

Classification under NIS2 and CRA

Rule-based classification from exploitation status and severity. It does not replace a case-by-case assessment.

NIS2 NIS2 is EU Directive (EU) 2022/2555 to raise the level of cybersecurity across the Union. It substantially broadens obligations compared with the first NIS directive: more sectors, mandatory risk management, staged reporting duties and personal accountability of senior management. Read in glossary: Actively exploited: treat the vulnerability as a priority in vulnerability handling under Art. 21(2)(e) NIS2. If it is exploited in your environment, check the reporting obligation under Art. 23 (early warning within 24 hours).
CRA The CRA is EU Regulation (EU) 2024/2847 setting horizontal cybersecurity requirements for „products with digital elements“ — from industrial controllers and software to connected consumer devices. For the first time manufacturers must ensure security across the entire product lifecycle, handle vulnerabilities and provide security updates. Read in glossary: Since 11.09.2026, manufacturers of affected products with digital elements must report actively exploited vulnerabilities under Art. 14 CRA, with an early warning within 24 hours via ENISA's single reporting platform.
ISO/IEC 27001 ISO/IEC 27001 is the internationally leading standard for an information security management system (ISMS). It describes a risk-based, process-oriented framework to systematically plan, implement, review and improve information security. Read in glossary: Control A.8.8, management of technical vulnerabilities: assess relevance to your systems, plan remediation and keep evidence.

Description

Windows SmartScreen Security Feature Bypass Vulnerability

Source: pwn.watch, NVD (NIST), cvelistv5, CISA KEV Catalog, CVE.org (MITRE)

Affected products

The following versions are affected. Older releases of the same product line are also vulnerable unless stated otherwise.

Affected products
		Affected versions	Fixed in
Microsoft	Windows 10 Version 1607	`10.0.14393.0 – < 10.0.14393.5786`	`10.0.14393.5786`
Microsoft	Windows 10 Version 1809	`10.0.17763.0 – < 10.0.17763.4131`	`10.0.17763.4131`
Microsoft	Windows 10 Version 20H2	`10.0.0 – < 10.0.19042.2728`	`10.0.19042.2728`
Microsoft	Windows 10 Version 21H2	`10.0.19043.0 – < 10.0.19044.2728`	`10.0.19044.2728`
Microsoft	Windows 10 Version 22H2	`10.0.19045.0 – < 10.0.19045.2728`	`10.0.19045.2728`
Microsoft	Windows 11 version 21H2	`10.0.0 – < 10.0.22000.1696`	`10.0.22000.1696`
Microsoft	Windows 11 version 22H2	`10.0.22621.0 – < 10.0.22621.1413`	`10.0.22621.1413`
Microsoft	Windows Server 2016	`10.0.14393.0 – < 10.0.14393.5786`	`10.0.14393.5786`
Microsoft	Windows Server 2016 (Server Core installation)	`10.0.14393.0 – < 10.0.14393.5786`	`10.0.14393.5786`
Microsoft	Windows Server 2019	`10.0.17763.0 – < 10.0.17763.4131`	`10.0.17763.4131`
Microsoft	Windows Server 2019 (Server Core installation)	`10.0.17763.0 – < 10.0.17763.4131`	`10.0.17763.4131`
Microsoft	Windows Server 2022	`10.0.20348.0 – < 10.0.20348.1607`	`10.0.20348.1607`

Vendors and products

Affected operating systems

Affected operating systems

Windows	microsoft	windows_10_1607	—
Windows	microsoft	windows_10_1809	—
Windows	microsoft	windows_10_20h2	—
Windows	microsoft	windows_10_21h2	—
Windows	microsoft	windows_10_22h2	—
Windows	microsoft	windows_11_21h2	—
Windows	microsoft	windows_11_22h2	—
Windows	microsoft	windows_server_2016	—
Windows	microsoft	windows_server_2019	—
Windows	microsoft	windows_server_2022	—

Weakness classes (CWE)

CWE-863Incorrect Authorization
Class
The product performs an authorization check when an actor attempts to access a resource or perform an action, but it does not correctly perform the check.
Entry at MITRE CWE-863

Public exploit references

Publicly reported proof-of-concepts, exploit modules and detection templates for this vulnerability. NEOSEC links to the original sources only and does not provide any exploit code.

Public exploit references

CISA KEV Catalog	CISA Known Exploited Vulnerability (opens in a new tab)cisa.gov	actively exploited	14.03.2023

References & sources

Microsoft Security Update GuideWindows SmartScreen Security Feature Bypass VulnerabilityVendor advisory, Patch, Vendor advisory
cisa.govknown-exploited-vulnerabilities-catalog?field_cve=CVE-2023-24880government-resource, US government resource
pwn.watchpwn.watch: Microsoft Windows: SmartScreen Security Feature Bypass (CVE-2023-24880)pwn-watch
Microsoft Security Update GuideVendor advisory: Microsoft Windowspwn-watch
NVD (NIST)NVD: CVE-2023-24880pwn-watch
cisa.govCISA Known Exploited Vulnerabilities Catalogpwn-watch

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<a href="https://intel.neosec.eu/en/cve/CVE-2023-24880"><img src="https://intel.neosec.eu/badge/cve/CVE-2023-24880.svg?lang=en" alt="CVE-2023-24880 – NEOSEC Intel" height="20"></a>

What is affected, what to do

Metrics

Response and mitigation

Prioritisation rationale

Immediate response (0-24 h)

Mitigation layers

Detection rules

Detection rules

Classification under NIS2 and CRA

Description

Affected products

Vendors and products

Affected operating systems

Weakness classes (CWE)

Public exploit references

References & sources