CVE-2015-6165 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-2015-6114.
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Analysis
by VulDB Data Team • 06/29/2022
Microsoft Silverlight 5 before version 5.1.41105.00 contains a critical vulnerability that undermines the operating system's address space layout randomization protection mechanism. This flaw enables remote attackers to bypass ASLR through carefully crafted web content, creating a significant security risk that affects the overall system integrity. The vulnerability specifically targets the way Silverlight handles memory layout and address space management within the browser environment, allowing attackers to predict memory addresses that should otherwise be randomized for security purposes. This represents a sophisticated exploitation technique that leverages the browser plugin's interaction with system memory management to circumvent fundamental security protections.
The technical implementation of this vulnerability stems from improper handling of memory addresses within the Silverlight runtime environment. Attackers can construct malicious web pages that trigger specific code paths in the Silverlight plugin, causing the system to reveal memory layout information that should remain randomized. This information disclosure allows adversaries to determine the base addresses of system libraries and memory regions, effectively nullifying the ASLR protection that is designed to prevent memory-based attacks. The vulnerability operates at the intersection of browser security and operating system memory management, exploiting a gap in how Silverlight interacts with the underlying system's security mechanisms. According to CWE standards, this maps to CWE-122, which deals with heap-based buffer overflow conditions, and CWE-200, which covers information exposure.
The operational impact of this vulnerability extends beyond simple information disclosure, as it enables more sophisticated attacks that rely on predictable memory layouts. Once ASLR bypass is achieved, attackers can execute additional exploits such as return-oriented programming attacks or other memory corruption techniques that would otherwise be impossible due to the randomized memory addresses. The vulnerability affects all systems running affected Silverlight versions and can be exploited through standard web browsing activities, making it particularly dangerous in enterprise environments where users frequently access untrusted websites. This weakness creates a pathway for privilege escalation and persistent access, as attackers can now craft more effective attacks against systems that should be protected by ASLR mechanisms. The attack vector requires only a malicious website, making it extremely difficult to defend against through traditional network security measures.
Organizations should immediately implement the security update released by Microsoft that patches this vulnerability in Silverlight version 5.1.41105.00 and later. System administrators should also consider disabling Silverlight plugins in browsers where they are not essential for business operations, particularly in environments where users access untrusted web content. Network monitoring should be enhanced to detect potential exploitation attempts through unusual memory access patterns or information disclosure behaviors. Security teams should implement application whitelisting policies to prevent unauthorized Silverlight plugin execution and consider deploying exploit prevention tools that can detect and block known exploitation patterns. The vulnerability's classification under ATT&CK technique T1059.007 (Command and Scripting Interpreter: PowerShell) and T1071.004 (Application Layer Protocol: DNS) indicates that attackers may leverage this vulnerability as part of broader attack chains involving command execution and data exfiltration. Regular security assessments should include testing for ASLR bypass capabilities to ensure that system protections remain effective against such sophisticated threats.