CVE-2016-3367 in Silverlight
Summary
by MITRE
StringBuilder in Microsoft Silverlight 5 before 5.1.50709.0 does not properly allocate memory for string-insert and string-append operations, which allows remote attackers to execute arbitrary code via a crafted web site, aka "Microsoft Silverlight Memory Corruption Vulnerability."
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Analysis
by VulDB Data Team • 10/07/2024
The vulnerability identified as CVE-2016-3367 represents a critical memory corruption issue within Microsoft Silverlight 5 before version 5.1.50709.0. This flaw exists in the StringBuilder component which is a fundamental part of Silverlight's string manipulation capabilities. The vulnerability arises from improper memory allocation handling during string-insert and string-append operations, creating a scenario where malicious actors can exploit the flawed memory management to execute arbitrary code on affected systems. Silverlight, being a rich internet application framework, was widely used for delivering multimedia content and interactive web applications, making this vulnerability particularly dangerous as it could be triggered through standard web browsing activities.
The technical nature of this vulnerability stems from the StringBuilder class's inadequate handling of memory allocation when processing string operations. When attackers craft malicious web content that triggers specific string manipulation sequences, the flawed memory management causes buffer overflows or memory corruption that can be leveraged for code execution. This type of vulnerability falls under CWE-121, which addresses stack-based buffer overflow conditions, and more specifically relates to improper memory handling in managed code environments. The flaw operates at the intersection of memory management and application security, where the expected bounds checking fails during string operations, allowing attackers to manipulate memory layout and potentially overwrite critical program structures.
The operational impact of CVE-2016-3367 extends beyond simple code execution as it represents a remote code execution vulnerability that can be exploited through web browsers without requiring any additional user interaction beyond visiting a malicious website. Attackers can craft specially designed web pages that, when loaded in a vulnerable Silverlight environment, trigger the memory corruption conditions. This vulnerability is particularly concerning because Silverlight was commonly enabled by default in many browsers, and the attack surface was broad as it could be triggered through standard web browsing activities. The exploitability factor is high due to the ease with which malicious websites can be created and distributed, and the widespread use of Silverlight applications across enterprise and consumer environments.
Organizations and security professionals should prioritize immediate mitigation of this vulnerability through the application of Microsoft's security patches, specifically updating to Silverlight 5.1.50709.0 or later versions. The recommended approach includes implementing browser security controls that either disable Silverlight plugin execution entirely or restrict its capabilities through sandboxing mechanisms. From an ATT&CK framework perspective, this vulnerability maps to T1059.007 for command and scripting interpreter and T1203 for Exploitation for Client Execution, as it enables attackers to execute arbitrary code on compromised systems. Additional defensive measures should include network monitoring for suspicious Silverlight-related traffic patterns and implementing application whitelisting policies that prevent execution of untrusted Silverlight content. The vulnerability also highlights the importance of maintaining up-to-date security patches and the risks associated with legacy application frameworks that are no longer actively supported by vendors.