CVE-2012-0176 in Silverlight
Summary
by MITRE
Double free vulnerability in Microsoft Silverlight 4 before 4.1.10329 on Windows allows remote attackers to execute arbitrary code via vectors involving crafted XAML glyphs, aka "Silverlight Double-Free Vulnerability."
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Analysis
by VulDB Data Team • 03/24/2021
The CVE-2012-0176 vulnerability represents a critical double free memory corruption issue within Microsoft Silverlight 4 before version 4.1.10329 on Windows systems. This vulnerability exists in the XAML glyph processing functionality of Silverlight, which is a multimedia framework used for creating rich internet applications. The flaw manifests when the Silverlight runtime encounters crafted XAML content containing specially constructed glyphs that trigger improper memory management during object deallocation. The vulnerability is classified under CWE-415 as a double free condition where the same memory block is freed twice, leading to unpredictable behavior and potential code execution.
The technical exploitation of this vulnerability occurs through remote code execution via malicious XAML content delivered through web browsers or other Silverlight-enabled applications. Attackers can craft XAML glyphs that, when processed by the vulnerable Silverlight runtime, cause the application to free the same memory location twice. This double free condition creates a memory corruption scenario that can be leveraged to execute arbitrary code with the privileges of the Silverlight application process. The attack vector specifically targets the XAML parsing engine within Silverlight, where the flaw exists in how the runtime manages memory allocation and deallocation for glyph objects during rendering operations. This vulnerability aligns with ATT&CK technique T1203, which covers exploitation of software vulnerabilities for privilege escalation and code execution.
The operational impact of CVE-2012-0176 extends beyond simple remote code execution as it provides attackers with a pathway to establish persistent access to affected systems. When successfully exploited, the vulnerability allows attackers to execute malicious code with the privileges of the Silverlight application, potentially leading to complete system compromise. The vulnerability affects a wide range of Windows systems running Silverlight 4 before the patched version, making it particularly dangerous in enterprise environments where Silverlight applications are commonly deployed. Organizations using Silverlight for business-critical applications face significant risk as this vulnerability can be exploited through web browsers, email attachments, or malicious websites without requiring user interaction beyond visiting a compromised site. The vulnerability's classification as a remote code execution flaw means that attackers do not need physical access to the target system, making it particularly concerning for organizations that rely on Silverlight for their web applications.
Mitigation strategies for CVE-2012-0176 primarily focus on immediate patch deployment and system hardening measures. Microsoft released security update 2661254 that addresses this vulnerability by correcting the memory management issues in the XAML glyph processing code. Organizations should prioritize patching all affected Silverlight installations to prevent exploitation. Additional mitigations include disabling Silverlight plugin support in web browsers, implementing network-based protections such as firewall rules that block Silverlight content from untrusted sources, and monitoring for suspicious XAML content in network traffic. The vulnerability demonstrates the importance of proper memory management practices in application development and highlights the need for regular security updates. Security teams should also consider implementing application whitelisting policies to prevent execution of untrusted Silverlight content, as this vulnerability could be exploited in conjunction with other attack techniques. Given the nature of memory corruption vulnerabilities, organizations should also implement exploit prevention mechanisms such as data execution prevention and address space layout randomization to limit the effectiveness of potential exploitation attempts.