CVE-2010-3975 in Flash Player
Summary
by MITRE
Untrusted search path vulnerability in Adobe Flash Player 9 allows local users, and possibly remote attackers, to execute arbitrary code and conduct DLL hijacking attacks via a Trojan horse schannel.dll that is located in the same folder as a file that is processed by Flash.
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Analysis
by VulDB Data Team • 01/07/2018
Adobe Flash Player 9 contains an untrusted search path vulnerability that enables local users and potentially remote attackers to execute arbitrary code through DLL hijacking techniques. This vulnerability stems from the improper handling of dynamic link library loading within the Flash Player runtime environment, creating a dangerous condition where malicious code can be loaded before legitimate system libraries. The specific flaw occurs when Flash Player processes files that require dynamic library loading, and the system searches for required DLLs in the same directory as the processed file before checking standard system locations. This behavior creates an opportunity for attackers to place a malicious schannel.dll file in the same directory as a Flash-compatible file, which the player will load instead of the legitimate system library.
The technical implementation of this vulnerability aligns with CWE-427 Uncontrolled Search Path Elements, where the search path is not properly controlled or validated. The flaw manifests when Flash Player loads third-party files that contain references to system libraries, particularly those related to secure channel communications. Attackers can exploit this by placing a specially crafted schannel.dll file in the directory containing a Flash file, such as an swf file, that the player will process. When the Flash Player attempts to load the required system library, it finds and executes the malicious version instead of the legitimate one, effectively bypassing normal security controls. This technique constitutes a classic DLL hijacking attack pattern that leverages the Windows dynamic loading mechanism.
The operational impact of this vulnerability extends beyond simple code execution to encompass potential privilege escalation and system compromise. Local attackers can leverage this vulnerability to execute arbitrary code with the privileges of the Flash Player process, which typically runs with the same privileges as the user who launched the application. Remote attackers could potentially exploit this through web-based attacks if they can influence the user to open a malicious Flash file, though the exact remote exploitation scenario would depend on additional attack vectors. The vulnerability creates a persistent threat because the malicious DLL remains in the directory where it was placed, allowing for repeated exploitation without requiring additional user interaction. This makes it particularly dangerous in environments where users frequently open files from untrusted sources.
Mitigation strategies for this vulnerability should focus on both immediate remediation and long-term architectural improvements. Adobe released patches for Flash Player 9 that addressed this specific search path issue by implementing proper library loading procedures and ensuring that system libraries are loaded from secure locations first. Organizations should immediately apply the relevant security updates and patches provided by Adobe to eliminate the vulnerability. Additionally, implementing proper file permissions and access controls can help prevent unauthorized DLL placement in directories containing Flash files. The principle of least privilege should be enforced, ensuring that Flash Player processes run with minimal required permissions. Network-level controls such as content filtering and application whitelisting can also help prevent exploitation attempts. This vulnerability demonstrates the importance of proper library loading practices and highlights the need for security-conscious development practices that consider the entire library search path when designing applications. The ATT&CK framework categorizes this as a technique involving DLL hijacking and privilege escalation, emphasizing the need for comprehensive defensive measures including process monitoring, file integrity checking, and security awareness training to prevent exploitation of such vulnerabilities.