CyberSecBulletin
CVE-2024-21351Exploited in the wildNVD status: Analyzed

Microsoft Windows SmartScreen Security Feature Bypass

Published Updated By the CyberSecBulletin desk

CVE-2024-21351 is a high-severity improper control of generation of code vulnerability in Windows 10 Version 1507 from Microsoft, with a CVSS 3.1 base score of 7.6 out of 10. It can be exploited remotely over the network by an unauthenticated attacker, but only if a user takes part, for example by opening a link or file. The record lists version 10.0.10240.20469 as the first without the flaw, so updating Windows 10 Version 1507 to that release or later removes the exposure. CISA added it to the Known Exploited Vulnerabilities catalogue on February 13, 2024, which means attacks have been observed in the wild.

Patch now

Attackers are already exploiting this vulnerability, according to CISA.

What to do

  1. Update Windows 10 Version 1507 to 10.0.10240.20469 or a later version.
  2. Update Windows 10 Version 1607 to 10.0.14393.6709 or a later version.
  3. Update Windows 10 Version 1809 to 10.0.17763.5458 or a later version.
  4. CISA's required action: Apply mitigations per vendor instructions or discontinue use of the product if mitigations are unavailable.
  5. Read the advisory on msrc.microsoft.com for workarounds and exact fixed builds.
  6. Until you can update, restrict network access to the affected service so it is not reachable from untrusted networks.
  7. Because the attack needs a user to take part, warn users about unexpected links and files related to this product until it is patched.

Affected products and versions

VendorProductAffected versionsFixed in
MicrosoftWindows 10 Version 150710.0.10240.0 up to, but not including, 10.0.10240.2046910.0.10240.20469
MicrosoftWindows 10 Version 160710.0.14393.0 up to, but not including, 10.0.14393.670910.0.14393.6709
MicrosoftWindows 10 Version 180910.0.17763.0 up to, but not including, 10.0.17763.5458; 10.0.0 up to, but not including, 10.0.17763.545810.0.17763.5458
MicrosoftWindows 10 Version 21H210.0.19043.0 up to, but not including, 10.0.19044.404610.0.19044.4046
MicrosoftWindows 10 Version 22H210.0.19045.0 up to, but not including, 10.0.19045.404610.0.19045.4046
MicrosoftWindows 11 version 21H210.0.0 up to, but not including, 10.0.22000.277710.0.22000.2777
MicrosoftWindows 11 version 22H210.0.22621.0 up to, but not including, 10.0.22621.315510.0.22621.3155
MicrosoftWindows 11 version 22H310.0.22631.0 up to, but not including, 10.0.22631.315510.0.22631.3155
MicrosoftWindows 11 Version 23H210.0.22631.0 up to, but not including, 10.0.22631.315510.0.22631.3155
MicrosoftWindows Server 201610.0.14393.0 up to, but not including, 10.0.14393.670910.0.14393.6709
MicrosoftWindows Server 201910.0.17763.0 up to, but not including, 10.0.17763.545810.0.17763.5458
MicrosoftWindows Server 202210.0.20348.0 up to, but not including, 10.0.20348.232210.0.20348.2322
MicrosoftWindows 10 1507before 10.0.10240.2046910.0.10240.20469
MicrosoftWindows 10 1607before 10.0.14393.670910.0.14393.6709
MicrosoftWindows 10 1809before 10.0.17763.545810.0.17763.5458
MicrosoftWindows 10 21h2before 10.0.19044.404610.0.19044.4046
MicrosoftWindows 10 22h2before 10.0.19045.404610.0.19045.4046
MicrosoftWindows 11 21h2before 10.0.22000.277710.0.22000.2777
MicrosoftWindows 11 22h2before 10.0.22621.315510.0.22621.3155
MicrosoftWindows 11 23h2before 10.0.22631.315510.0.22631.3155
MicrosoftWindows Server 2022 23h2before 10.0.25398.70910.0.25398.709

Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.

How the severity score breaks down

Attack vector
NetworkCan be exploited remotely over a network, including the internet.
Attack complexity
LowNo special conditions are needed; the attack works reliably.
Privileges required
NoneNo account or login is needed.
User interaction
RequiredA user must take an action such as opening a file or link.
Scope
UnchangedImpact stays within the vulnerable component.
Confidentiality
LowSome restricted data can be read.
Integrity
HighData or code can be modified at will.
Availability
LowPerformance or availability is reduced.

Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:H/A:L. Scored by CNA (microsoft.com).

Official description

Windows SmartScreen Security Feature Bypass Vulnerability

Source: the CVE record as published by its numbering authority, via NVD and CVE.org.

The underlying weakness: Improper Control of Generation of Code

The product constructs all or part of a code segment using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify the syntax or behavior of the intended code segment.

How developers prevent this class of flaw

  • Refactor your program so that you do not have to dynamically generate code.
  • Run your code in a jail or similar sandbox environment that enforces strict boundaries between the process and the operating system. This may effectively restrict which code can be executed by your product. Examples include the Unix chroot jail and AppArmor. In general, managed code may provide some protection. This may not be a feasible solution, and it only limits the impact to the operating system; the rest of your application may still be subject to compromise. Be careful to avoid CWE-243 and other weaknesses related to jails.
  • Use dynamic tools and techniques that interact with the product using large test suites with many diverse inputs, such as fuzz testing (fuzzing), robustness testing, and fault injection. The product's operation may slow down, but it should not become unstable, crash, or generate incorrect results.

More Improper Control of Generation of Code vulnerabilities (CWE-94)

Timeline

  1. CVE record published.
  2. Added to CISA's Known Exploited Vulnerabilities catalogue.
  3. Deadline for US federal agencies to remediate, set by CISA.
  4. CISA published its SSVC assessment (exploitation: active, automatable: no, technical impact: partial).
  5. Record last changed materially (score, affected products, status or references).

References

Third-party and government advisories

Other vulnerabilities in Windows 10 Version 1507

All Windows 10 Version 1507 vulnerabilities

Recent Improper Control of Generation of Code vulnerabilities

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