The Heartbleed vulnerability in OpenSSL (CVE-2014-0160) has received a significant amount of attention recently.  While the discovered issue is specific to OpenSSL, many customers are wondering whether this affects Microsoft’s offerings, specifically Microsoft Azure. Microsoft Account and Microsoft Azure, along with most Microsoft Services, were not impacted by the OpenSSL vulnerability. Windows’ implementation of SSL/TLS was also not impacted.

Microsoft Azure Web Sites, Microsoft Azure Pack Web Sites and Microsoft Azure Web Roles do not use OpenSSL to terminate SSL connections.  Windows comes with its own encryption component called Secure Channel (a.k.a. SChannel), which is not susceptible to the Heartbleed vulnerability.

OpenSSL is a common library on Linux for providing encryption functionality.  Customers running Linux images in Azure Virtual Machines, or software which uses OpenSSL, may be vulnerable.  We recommend that all customers who may be vulnerable follow the guidance from their software distribution provider.  For more information and corrective action guidance, please see the information from US Cert here.