Technical Information

Brief overview of the risk:
This security update resolves publicly disclosed vulnerabilities in Microsoft Exchange Server. The most severe vulnerability is in Microsoft Exchange Server WebReady Document Viewing, and could allow remote code execution in the security context of the transcoding service on the Exchange server if a user previews a specially crafted file using Outlook Web App (OWA). The transcoding service in Exchange that is used for WebReady Document Viewing is running in the LocalService account. The LocalService account has minimum privileges on the local computer and presents anonymous credentials on the network.

Detailed Information on the risk:

Two vulnerabilities exist in Microsoft Exchange Server through the WebReady Document Viewing feature. The more severe vulnerability, CVE-2013-0418, could allow remote code execution as the LocalService account if a user views a specially crafted file through Outlook Web Access in a browser. An attacker who successfully exploited this vulnerability could run code on the affected Exchange Server, but only as the LocalService account. The LocalService account has minimum privileges on the local computer and presents anonymous credentials on the network. The other vulnerability, CVE-2013-0393, could cause the affected Exchange Server to become unresponsive if a user views a specially crafted file through Outlook Web Access in a browser. Note that CVE-2013-0393 would not allow an attacker to execute code or to elevate user rights.

Further information on this exploit is available at : MS13-012