Remote denial of service in SymCrypt library in Microsoft Windows



Published: 2019-06-13
Risk Medium
Patch available NO
Number of vulnerabilities 1
CVE-ID N/A
CWE-ID CWE-310
Exploitation vector Network
Public exploit Public exploit code for vulnerability #1 is available.
Vulnerable software
Subscribe 		SymCrypt
Universal components / Libraries / Libraries used by multiple products

Windows
Operating systems & Components / Operating system

Windows Server
Operating systems & Components / Operating system

Vendor Microsoft

Security Bulletin

This security bulletin contains one medium risk vulnerability.

1) Cryptographic issues

EUVDB-ID: #VU18788

Risk: Medium

CVSSv3.1: 5.6 [CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H/E:P/RL:U/RC:C]

CVE-ID: N/A

CWE-ID: CWE-310 - Cryptographic Issues

Exploit availability: No

Description

The vulnerability allows a remote attacker to perform a denial of service (DoS) attack.

The vulnerability exists due to an error when calculating the modular inverse on specific bit patterns with bcryptprimitives!SymCryptFdefModInvGeneric() function when processing X.509 certificates. A remote attacker can supply a specially crafted X.509 certificate to the affected system and trigger denial of service conditions.

Any application that uses the vulnerable library, e.g. antivirus software is susceptible to this issue.


Mitigation

Install updates from vendor's website.

Vulnerable software versions

SymCrypt: All versions

Windows: 8.1 - 10 Gold

Windows Server: 2012 - 2019 1903

External links

http://bugs.chromium.org/p/project-zero/issues/detail?id=1804


Q & A

Can this vulnerability be exploited remotely?

Yes. This vulnerability can be exploited by a remote non-authenticated attacker via the Internet.

Is there known malware, which exploits this vulnerability?

No. We are not aware of malware exploiting this vulnerability. However, proof of concept for this vulnerability is available.



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