CVE-2015-6114 in Silverlight
Summary
by MITRE
Microsoft Silverlight 5 before 5.1.41105.00 allows remote attackers to bypass the ASLR protection mechanism via a crafted web site, aka "Microsoft Silverlight Information Disclosure Vulnerability," a different vulnerability than CVE-2015-6165.
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Analysis
by VulDB Data Team • 06/30/2022
Microsoft Silverlight 5 before version 5.1.41105.00 contains a critical vulnerability that undermines the Address Space Layout Randomization security mechanism, creating a pathway for remote attackers to bypass important memory protection controls. This vulnerability specifically affects the browser plugin implementation and represents a distinct security flaw from CVE-2015-6165, which addresses different aspects of Silverlight's security architecture. The vulnerability stems from improper handling of memory layout information within the Silverlight runtime environment, allowing malicious actors to predict memory addresses and potentially execute arbitrary code. This weakness enables attackers to circumvent the ASLR protection that randomizes the memory layout of running processes, making it significantly easier to exploit other vulnerabilities present in the Silverlight runtime. The attack vector requires a malicious website that can be accessed through a web browser with Silverlight installed, making it particularly dangerous in enterprise environments where users frequently browse untrusted websites.
The technical flaw manifests in how Silverlight handles memory address randomization during runtime execution, specifically within the plugin's memory management subsystem. When a Silverlight application loads, the runtime should randomize memory locations for key components including code segments, data structures, and heap allocations to prevent attackers from predicting memory addresses. However, the vulnerability allows attackers to extract memory layout information through carefully crafted web content that leverages Silverlight's scripting capabilities and memory access patterns. This information disclosure enables attackers to determine the base addresses of key memory regions, effectively neutralizing the ASLR protection that should make exploitation of other vulnerabilities significantly more difficult. The vulnerability is categorized under CWE-200 as an information disclosure weakness, where sensitive system information is exposed that could be used for further exploitation.
The operational impact of this vulnerability extends beyond simple information disclosure, creating a significant security risk for organizations that still rely on Silverlight-based applications. Attackers who successfully exploit this vulnerability can use the leaked memory addresses to bypass stack canaries, ASLR, and DEP protections, making it possible to execute shellcode or other malicious payloads against systems with vulnerable Silverlight installations. This vulnerability particularly affects enterprise environments where Silverlight applications are deployed for business-critical functions, as it provides a pathway for attackers to escalate privileges and gain unauthorized access to sensitive systems. The attack requires only a web browser with Silverlight enabled, making it easily exploitable in typical enterprise scenarios where users access business applications through web browsers. Organizations with legacy Silverlight applications continue to face elevated risk from this vulnerability, especially when these applications are accessed through unpatched browsers or systems.
Organizations should implement immediate mitigations including disabling Silverlight plugin execution in web browsers, applying the vendor-provided security update to version 5.1.41105.00, and implementing network-level controls to prevent access to known malicious Silverlight content. System administrators should also consider deploying application whitelisting policies to restrict Silverlight execution to trusted applications only, while monitoring for suspicious memory access patterns that might indicate exploitation attempts. The vulnerability aligns with ATT&CK technique T1059.007 for command and scripting interpreter, as attackers may leverage Silverlight's scripting capabilities to execute malicious code. Additionally, this vulnerability demonstrates the importance of maintaining up-to-date security patches across all system components, as the vulnerability exists in the browser plugin rather than in the core operating system, making it a prime example of how third-party plugins can create security exposure points. Regular security assessments should include evaluation of legacy plugin components and their potential to undermine modern security controls, particularly those that provide memory protection mechanisms like ASLR.