![]() ![]() Throw new Exception("PFX blobs are disallowed.") If (X509Certificate2.GetCertContentType(blob) = X509ContentType.Pfx) Public static X509Certificate2 ImportPublicCertificateBlob(byte blob) The X509Certificate2(byte) constructor is safe for use when given untrusted non-PFX blobs. This sample code uses the GetCertContentType method to determine what the underlying type of the certificate blob is, and it rejects PFX blobs in cases where you only expect to import a public key certificate blob. If you need to import a public key certificate blob given to you by an untrusted party, you can use the following code to safely import such a blob. Microsoft strongly recommends that you do not import PFX blobs provided to you by unauthenticated or unprivileged clients, as these blobs could contain malicious resource exhaustion behaviors. For example, was the blob retrieved from a trusted location, like a database or config file under your control, or was it provided via a network request made by an unauthenticated or unprivileged client? NET.Ĭonsider whether the blob you're importing is trustworthy. Microsoft recommends that customers who are experiencing regressions introduced by the June 13, 2023, release try installing this updated patch before attempting the workarounds listed later in this document.Īpplicability: This option applies to all versions of. This issue has been addressed in the JUpdate discussed in KB5028608. Note: This is the preferred option since it addresses commonly reported customer regressions and does not require any code changes to the application.Īpplicability: This option applies to all versions of. ![]() Option 1 (preferred) - Install an updated patch Various workarounds exist, depending on whether you want to make targeted changes at individual call sites within your code, or you want to change the behavior of a single application, or you want to make machine-wide changes. Via the PFXExportCertStoreEx API where the PKCS12_PROTECT_TO_DOMAIN_SIDS flag is provided. Via the certutil utility where an explicit -protectto argument is provided or Via PowerShell's Export-PfxCertificate cmdlet where an explicit -ProtectTo argument is provided or Via Windows's Certificate Export Wizard and specifying in the wizard that the private key should be protected to a domain user or This will impact PFX blobs created in the following manners: If an X.509 certificate has been exported as a PFX blob using Windows's capability to protect the private key to a SID, that certificate may now fail to import. Note: The above regression has been addressed in the JUpdate discussed in KB5028608. If an X.509 certificate has been exported using a null password, that certificate may now fail to import. After the security update is applied, import will fail for certificates containing an iteration count greater than 600,000. Most certificate export facilities use an iteration count somewhere between 2,000 - 10,000. If an X.509 certificate has been exported as a PFX blob using an uncommonly high password iteration count, that certificate may now fail to import. Since this is additional validation beyond what the underlying OS would normally perform, it may block certificate blobs which would have successfully imported prior to the June 13, 2023, change. This additional validation performs a series of heuristic checks to determine if the incoming certificate would maliciously exhaust resourcese upon import. NET will in some circumstances perform additional validation before handing the blob to the underlying OS. NET is presented with a binary certificate blob for import. NET would typically rely on the PFXImportCertStore API for validation and import.Īs of the June 13, 2023, change, when. NET would typically delegate validation and import of the blob to the underlying OS. Prior to the June 13, 2023, change, when. This document describes the change and workarounds available for impacted applications. These changes may cause X.509 certificate import to throw CryptographicException in scenarios where import would have succeeded prior to the update. NET which impacts how the runtime imports X.509 certificates. On June 13, 2023, Microsoft released a security update to. Note: Revised Jto update work around options 4 and 5 Note: Revised Jto update resolution and workarounds ![]()
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