Microsoft Identity Web Exposes Client Secrets and Certificate Information in Service Logs

Impact

What kind of vulnerability is it? Who is impacted?

Description: This vulnerability affects confidential client applications, including daemons, web apps, and web APIs. Under specific circumstances, sensitive information such as client secrets or certificate details may be exposed in the service logs of these applications. Service logs are intended to be handled securely.

Impact: The vulnerability impacts service logs that meet the following criteria:

• Logging Level: Logs are generated at the information level.
• Credential Descriptions: containing:
  • Local file paths with passwords.
  • Base64 encoded values.
  • Client secret.

Additionally, logs of services using Base64 encoded certificates or certificate paths with password credential descriptions are also affected if the certificates are invalid or expired, regardless of the log level. Note that these credentials are not usable due to their invalid or expired status.

If your service logs are handled securely, you are not impacted.

Otherwise, the following table shows when you can be impacted

	Log Level Information for Microsoft.Identity.Web	Invalid Certificate
One of the ClientCredentials credential description has a CredentialSource = Base64Encoded or (CredentialSource = Path)	Impacted	Impacted
One of the ClientCredentials credential description is a Client secret (CredentialSource = ClientSecret)	Impacted	Not impacted
Other credential descriptions	Not Impacted	Not Impacted

Patches

Has the problem been patched? What versions should users upgrade to? To mitigate this vulnerability, update to Microsoft.Identity.Web 3.8.2 or Microsoft.Identity.Abstractions 9.0.0.

Workarounds

Is there a way for users to fix or remediate the vulnerability without upgrading? You can work around the issue in the following ways:

• Ensure that service logs are handled securely and access to logs is restricted

• Don’t use LogLevel = Information for the Microsoft.Identity.Web namespace

Recommendation for production environment

Avoid using ClientCredentials with CredentialDescriptions which CredentialSource is ClientSecret, or Base64Encoded, or Path. Rather use certificate from KeyVault or a certificate store, or Federation identity credential with Managed identity.

References

Are there any links users can visit to find out more?