CyberSecBulletin
CVE-2020-0601Exploited in the wildNVD status: Analyzed

Microsoft Windows CryptoAPI Spoofing

Published Updated By the CyberSecBulletin desk

CVE-2020-0601 is a high-severity improper certificate validation vulnerability in Windows from Microsoft, with a CVSS 3.1 base score of 8.1 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. Affected Windows versions: 10 Version 1803 for 32-bit Systems; 10 Version 1803 for x64-based Systems; 10 Version 1803 for ARM64-based Systems, and others listed below. The record does not name a fixed version, so check the vendor advisory. CISA added it to the Known Exploited Vulnerabilities catalogue on November 3, 2021, 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 Go to 1.12.16 or 1.13.7, whichever matches your release line, or a later version.
  2. CISA's required action: Apply updates per vendor instructions.
  3. Read the advisory on portal.msrc.microsoft.com for workarounds and exact fixed builds.
  4. Until you can update, restrict network access to the affected service so it is not reachable from untrusted networks.
  5. 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
MicrosoftWindows10 Version 1803 for 32-bit Systems; 10 Version 1803 for x64-based Systems; 10 Version 1803 for ARM64-based Systems; 10 Version 1809 for 32-bit Systems; 10 Version 1809 for x64-based Systems; 10 Version 1809 for ARM64-based Systems; 10 Version 1709 for 32-bit Systems; 10 Version 1709 for x64-based Systems; and 5 more rangesNot stated
MicrosoftWindows Serverversion 1803 (Core Installation); 2019; 2019 (Core installation); 2016; 2016 (Core installation)Not stated
MicrosoftWindows 10 Version 1903 for 32-bit SystemsNot specified in the recordNot stated
MicrosoftWindows 10 Version 1903 for x64-based SystemsNot specified in the recordNot stated
MicrosoftWindows 10 Version 1903 for ARM64-based SystemsNot specified in the recordNot stated
MicrosoftWindows Server, version 1903 (Server Core installation)Not specified in the recordNot stated
MicrosoftWindows 10 Version 1909 for 32-bit SystemsNot specified in the recordNot stated
MicrosoftWindows 10 Version 1909 for x64-based SystemsNot specified in the recordNot stated
MicrosoftWindows Server, version 1909 (Server Core installation)Not specified in the recordNot stated
MicrosoftWindows 10 Version 1909 for ARM64-based SystemsNot specified in the recordNot stated
MicrosoftWindows 10 1507Not specified in the recordNot stated
MicrosoftWindows 10 1607Not specified in the recordNot stated
MicrosoftWindows 10 1709Not specified in the recordNot stated
MicrosoftWindows 10 1803Not specified in the recordNot stated
MicrosoftWindows 10 1809Not specified in the recordNot stated
MicrosoftWindows 10 1903Not specified in the recordNot stated
MicrosoftWindows 10 1909Not specified in the recordNot stated
MicrosoftWindows Server 1803Not specified in the recordNot stated
MicrosoftWindows Server 1903Not specified in the recordNot stated
MicrosoftWindows Server 1909Not specified in the recordNot stated
MicrosoftWindows Server 2016Not specified in the recordNot stated
MicrosoftWindows Server 2019Not specified in the recordNot stated
GoGo1.12 up to, but not including, 1.12.16; 1.13 up to, but not including, 1.13.71.12.16, 1.13.7

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
HighAll data handled by the component can be read.
Integrity
HighData or code can be modified at will.
Availability
NoneAvailability is not affected.

Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:N. Scored by NVD.

Scoring systemScoreSeverityScored by
CVSS 3.18.1HighNVD
CVSS 3.18.1HighCISA (ADP)
CVSS 2.05.8MediumNVD

Official description

A spoofing vulnerability exists in the way Windows CryptoAPI (Crypt32.dll) validates Elliptic Curve Cryptography (ECC) certificates.An attacker could exploit the vulnerability by using a spoofed code-signing certificate to sign a malicious executable, making it appear the file was from a trusted, legitimate source, aka 'Windows CryptoAPI Spoofing Vulnerability'.

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

The underlying weakness: Improper Certificate Validation

The product does not validate, or incorrectly validates, a certificate.

How developers prevent this class of flaw

  • Certificates should be carefully managed and checked to assure that data are encrypted with the intended owner's public key.
  • If certificate pinning is being used, ensure that all relevant properties of the certificate are fully validated before the certificate is pinned, including the hostname.

More Improper Certificate Validation vulnerabilities (CWE-295)

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: total).
  5. Record last changed materially (score, affected products, status or references).

References

Other vulnerabilities in Windows

All Windows vulnerabilities

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