==================================================================== CERT-Renater Note d'Information No. 2015/VULN181 _____________________________________________________________________ DATE : 09/09/2015 HARDWARE PLATFORM(S): / OPERATING SYSTEM(S): Systems running Skype for Business Server version 2015, Microsoft Lync Server version 2013. ====================================================================== KB3089952 https://technet.microsoft.com/en-us/library/security/MS15-104 ______________________________________________________________________ Microsoft Security Bulletin MS15-104: Important Vulnerabilities in Skype for Business Server and Lync Server Could Allow Elevation of Privilege (3089952) Bulletin Number: MS15-104 Bulletin Title: Important Vulnerabilities in Skype for Business Server and Lync Server Could Allow Elevation of Privilege Severity: Important KB Article: 3089952 Version: 1.0 Published Date: September 8, 2015 Executive Summary This security update resolves vulnerabilities in Skype for Business Server and Microsoft Lync Server. The most severe of the vulnerabilities could allow elevation of privilege if a user clicks a specially crafted URL. An attacker would have to convince users to click a link in an instant messenger or email message that directs them to an affected website by way of a specially crafted URL. This security update is rated Important for all supported editions of Skype for Business Server 2015 and Microsoft Lync Server 2013. For more information, see the Affected Software section. Affected Software Microsoft Lync Server 2013 (Web Components Server) Skype for Business Server 2015 (Web Components Server) Skype for Business Server 2015 (Enterprise Web App) Vulnerability Information Skype for Business Server and Lync Server XSS Information Disclosure Vulnerability - CVE-2015-2531 A cross-site scripting (XSS) vulnerability, which could result in information disclosure, exists when the jQuery engine in Skype for Business Server or in Lync Server fails to properly sanitize specially crafted content. An attacker who successfully exploited this vulnerability could potentially execute scripts in the users browser to obtain information from web sessions. For this vulnerability to be exploited, a user must click a specially crafted URL. In an email attack scenario, an attacker could exploit the vulnerability by sending an email message containing the specially crafted URL to the user and by convincing the user to click on the specially crafted URL. In a web-based attack scenario, an attacker would have to host a website that contains a specially crafted URL. In addition, compromised websites and websites that accept or host user-provided content could contain specially crafted content that could exploit this vulnerability. An attacker would have no way to force users to visit such websites. Instead, an attacker would have to convince users to visit the website, typically by getting them to click a link in an instant messenger or email message that directs them to the affected website by way of a specially crafted URL. , Microsoft Office, Microsoft Live Meeting Systems with affected editions of Skype for Business Server or Microsoft Lync Server installed and the clients that connect to them are at risk from this vulnerability. The update addresses the vulnerability by updating jQuery in Skype for Business Server and in Lync Server to correctly sanitize user input. Microsoft received information about this vulnerability through coordinated vulnerability disclosure. When this security bulletin was originally issued Microsoft had not received any information to indicate that this vulnerability had been publicly used to attack customers. Lync Server XSS Information Disclosure Vulnerability - CVE-2015-2532 A cross-site scripting (XSS) vulnerability, which could result in information disclosure, exists when Lync Server fail to properly sanitize specially crafted content. An attacker who successfully exploited this vulnerability could potentially execute scripts in the users browser to obtain information from web sessions. For this vulnerability to be exploited, a user must click a specially crafted URL. In an email attack scenario, an attacker could exploit the vulnerability by sending an email message containing the specially crafted URL to the user and by convincing the user to click on the specially crafted URL. In a web-based attack scenario, an attacker would have to host a website that contains a specially crafted URL. In addition, compromised websites and websites that accept or host user-provided content could contain specially crafted content that could exploit this vulnerability. An attacker would have no way to force users to visit a specially crafted website. Instead, an attacker would have to convince users to visit the website, typically by getting them to click a link in an instant messenger or email message that directs them to the affected website by way of a specially crafted URL. Systems with affected editions of Microsoft Lync Server installed and the clients that connect to them are at risk from this vulnerability. The update addresses the vulnerability by correcting how Lync Server sanitizes user input. Microsoft received information about this vulnerability through coordinated vulnerability disclosure. When this security bulletin was originally issued Microsoft had not received any information to indicate that this vulnerability had been publicly used to attack customers. Skype for Business Server and Lync Server XSS Elevation of Privilege Vulnerability - CVE-2015-2536 A cross-site scripting (XSS) vulnerability, which could result in elevation of privileges, exists when Skype for Business Server or Lync Server fails to properly sanitize specially crafted content. An attacker who successfully exploited this vulnerability could execute arbitrary code and take control of an affected system. An attacker could then install programs; view, change, or delete data; or create new accounts with full user rights. For this vulnerability to be exploited, a user must click a specially crafted URL. In an email attack scenario, an attacker could exploit the vulnerability by sending an email message containing the specially crafted URL to the user and by convincing the user to click on the specially crafted URL. In a web-based attack scenario, an attacker would have to host a website that contains a specially crafted URL. In addition, compromised websites and websites that accept or host user-provided content could contain specially crafted content that could exploit this vulnerability. An attacker would have no way to force users to visit a specially crafted website. An attacker would have no way to force users to visit such websites. Instead, an attacker would have to convince users to visit the website, typically by getting them to click a link in an instant messenger or email message that directs them to the affected website by way of a specially crafted URL. Systems with affected editions of Skype for Business Server or Microsoft Lync Server installed and the clients that connect to them are at risk from this vulnerability. The update addresses the vulnerability by correcting how Lync Server sanitizes user input. Microsoft received information about this vulnerability through coordinated vulnerability disclosure. When this security bulletin was originally issued Microsoft had not received any information to indicate that this vulnerability had been publicly used to attack customers. ========================================================= Serveur de référence du CERT-Renater https://services.renater.fr/ssi/ ========================================================== + CERT-RENATER | tel : 01-53-94-20-44 + + 23 - 25 Rue Daviel | fax : 01-53-94-20-41 + + 75013 Paris | email: cert@support.renater.fr + ==========================================================