!!! Overview
[{$pagename}] (also known variously as [Crypt32.dll], Microsoft Cryptography API, MS-CAPI or simply CAPI) is a [Microsoft Windows] [API] provides [Cryptosystem] services that enable developers to secure Windows-based [applications] using [cryptography], and includes functionality for [Encryption] and [Decryption] [data] using digital [certificates].
[{$pagename}] uses the [crypt32.dll] which is a [Microsoft Windows] [Software library] that "[certificate] and [cryptographic] [Message] [functions].
[{$pagename}] was first introduced in [Windows NT] 4.0
!! [CVE-2020-0601|https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2020-0601|target='_blank'] (aka CurveBall)
At a high level, this [vulnerability] takes advantage of the fact that Crypt32.dll fails to properly check that the
[Elliptic Curve] parameters specified in a provided [Root Certificate] match those known to [Microsoft].
This is considered a [spoofing] [vulnerability] that exists in the way [Microsoft Windows] [{$pagename}] ([Crypt32.dll]) validates [Digitally Signed] [messages] on [Elliptic Curve] [Cryptography] (ECC). There are at least two instances demonstrated where an [attacker] could exploit the [vulnerability]:
* by using a spoofed [code]-signing [certificate] to sign a [malicious] executable
* the [attacker] to conduct [Man-In-The-Middle] [attacks] and decrypt [confidential] information on user connections to the affected software.
In both of these it appears the [Digitally Signed] file was from a trusted, legitimate source, aka 'Windows CryptoAPI Spoofing Vulnerability'.
You should also examine their [Windows Event Log] for instances of the new CveEventWrite event, which indicates active exploitation of the [vulnerability] in an environment
The [vulnerability] exists in these products:
* [Windows 10] (all build numbers)
* [Windows Server 2016]
* [Windows Server 2019]
Older versions of Windows are __not affected__.
As of Jan. 15, [2020|Year 2020], this [vulnerability] is known to be exploited in the wild and the [Attack Effort] is considered low. The first proof-of-concept "fake ID generators" are out – a Python program of 53 lines, and a Ruby script of just 21 and they really are sitting there for anyone to use for free.
Visit [https://curveballtest.com|https://curveballtest.com|target='_blank'] to test if your browser is vulnerable
!! More Information
There might be more information for this subject on one of the following:
[{ReferringPagesPlugin before='*' after='\n' }]
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* [#1] - [Microsoft_CryptoAPI|Wikipedia:Microsoft_CryptoAPI|target='_blank'] - based on information obtained 2020-01-23
* [#2] - [Cryptic Rumblings Ahead of First 2020 Patch Tuesday|https://krebsonsecurity.com/2020/01/cryptic-rumblings-ahead-of-first-2020-patch-tuesday/#more-50171|target='_blank'] - based on information obtained 2020-01-17
* [#3] - [Patch Critical Cryptographic Vulnerability in Microsoft Windows
Clients and Servers|https://media.defense.gov/2020/Jan/14/2002234275/-1/-1/0/CSA-WINDOWS-10-CRYPT-LIB-20190114.PDF|target='_blank'] - based on information obtained 2020-01-17
* [#4] - [CVE-2020-0601 - Windows CryptoAPI Spoofing Vulnerability|https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2020-0601|target='_blank'] - based on information obtained 2020-01-17
* [#5] - [CVE-2020-0601 Detail|https://nvd.nist.gov/vuln/detail/CVE-2020-0601#vulnCurrentDescriptionTitle|target='_blank'] - based on information obtained 2020-01-23
* [#6] - [Win10 Crypto Vulnerability: Cheating in Elliptic Curve Billiards 2|https://medium.com/zengo/win10-crypto-vulnerability-cheating-in-elliptic-curve-billiards-2-69b45f2dcab6|target='_blank'] - based on information obtained 2020-01-23
* [#7] - [CurveBall’s Additional Twist: The Certificate Comparison Bug|https://medium.com/zengo/curveballs-additional-twist-the-certificate-comparison-bug-2698aea445b5|target='_blank'] - based on information obtained 2020-01-23
* [#8] - [NSA and Github ‘rickrolled’ using Windows CryptoAPI bug|https://nakedsecurity.sophos.com/2020/01/16/nsa-and-github-rickrolled-using-windows-cryptoapi-bug/|target='_blank'] - based on information obtained 2020-01-23
* [#2] - [CVE-2020-0601 Followup|https://isc.sans.edu/forums/diary/CVE20200601+Followup/25714/|target='_blank'] - based on information obtained 2020-01-23