Vulnerabilities in XnViewer Could Allow Remote Code Execution

Executive Summary

Microsoft is providing notification of the discovery and remediation of two integer overflow vulnerabilities affecting XnViewer version 1.98.2 and earlier versions. Microsoft discovered and disclosed the vulnerabilities under coordinated vulnerability disclosure to the affected vendor, XnView. XnView has remediated the vulnerabilities in their software.

Both integer overflow vulnerabilities exist in the way that XnViewer handles certain PSD record types. Both vulnerabilities could allow remote code execution if a user opens a specially crafted file with an affected version of XnViewer. An attacker who successfully exploited either of these vulnerabilities could run arbitrary code in the security context of the logged-on user. If a user is logged on with administrative user rights, an attacker who successfully exploited this vulnerability could take complete control of an affected system. An attacker could then install programs; view, change, or delete data; or create new accounts with full user rights.

Microsoft Vulnerability Research reported these issues to and coordinated with XnView to ensure remediation. The vulnerabilities have been assigned the entries CVE-2012-0684 and CVE-2012-0685 in the Common Vulnerabilities and Exposures list. For more information about updates from XnView, please see the XnViewer download page.

Mitigating Factors

• The vulnerabilities cannot be exploited automatically through email. For an attack to be successful, a user must open an attachment that is sent in an email message.
• In a web-based attack scenario, an attacker could host a website that contains a specially crafted file that is used to exploit either of these vulnerabilities. In addition, compromised websites and websites that accept or host user-provided content or advertisements could contain specially crafted content that could exploit either of these vulnerabilities. In all cases, however, an attacker would have no way to force users to visit these websites. Instead, an attacker would have to convince users to visit the website, typically by getting them to click a link in an email message or Instant Messenger message that takes users to the attacker’s website, and then convince them to open the specially crafted file.
• An attacker who successfully exploited either of these vulnerabilities could gain the same user rights as the logged-on user. Users whose accounts are configured to have fewer user rights on the system could be less impacted than users who operate with administrative user rights.