CVE-2016-7871 in Flash Player
Summary
by MITRE
Adobe Flash Player versions 23.0.0.207 and earlier, 11.2.202.644 and earlier have an exploitable memory corruption vulnerability in the Worker class. Successful exploitation could lead to arbitrary code execution.
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Analysis
by VulDB Data Team • 10/08/2022
Adobe Flash Player contained a critical memory corruption vulnerability in its Worker class implementation that affected versions up to and including 23.0.0.207 and 11.2.202.644. This vulnerability stems from improper handling of memory allocation and deallocation within the multithreaded Worker class functionality, creating a condition where attackers could manipulate memory pointers and execute arbitrary code on affected systems. The flaw represents a classic heap-based buffer overflow scenario where insufficient bounds checking allowed malicious input to overwrite adjacent memory locations, potentially leading to privilege escalation and system compromise. The Worker class in Flash Player enables multithreaded operations for background processing, but the implementation lacked proper memory management safeguards that would normally prevent such corruption scenarios. This vulnerability aligns with CWE-121, heap-based buffer overflow, and specifically manifests as a memory safety issue within Adobe's multimedia runtime environment. The attack surface is particularly concerning as it leverages the legitimate multithreading capabilities of Flash Player to create an execution path that bypasses standard security mechanisms. Security researchers identified that the vulnerability could be triggered through malicious SWF files or web content that utilizes the Worker class functionality, making it highly exploitable in web-based attack scenarios. The impact extends beyond simple code execution to potential privilege escalation, as attackers could leverage the corrupted memory state to gain elevated system privileges. This flaw demonstrates the inherent risks associated with complex runtime environments that handle multiple execution threads and memory management operations, particularly when legacy code implementations lack modern safety checks. Organizations running affected Flash Player versions faced significant risk exposure, as the vulnerability could be exploited through standard web browsing activities without requiring user interaction beyond visiting compromised websites. The exploitation chain typically involves crafting malicious content that triggers the Worker class memory corruption, followed by payload delivery that executes in the context of the Flash Player process, potentially leading to full system compromise. This vulnerability highlights the importance of proper memory management in runtime environments and the need for comprehensive input validation across all application components, particularly those handling concurrent operations. The flaw represents a fundamental security weakness in Adobe's implementation of multithreading capabilities, where the benefits of parallel processing were achieved at the cost of introducing exploitable memory corruption conditions. Mitigation strategies required immediate patching of Flash Player installations, along with web content filtering and sandboxing measures to prevent exploitation of the vulnerability. The incident underscored the critical importance of maintaining up-to-date security patches for multimedia runtime environments, as these components often serve as attack vectors due to their extensive functionality and complex memory management requirements. This vulnerability also demonstrated how seemingly benign features like multithreading can become security risks when not properly implemented with adequate safety mechanisms and memory validation checks. The exploitation of this vulnerability through web-based attack vectors made it particularly dangerous for enterprise environments where users frequently accessed untrusted web content through Flash-enabled browsers and applications. Security professionals noted that the vulnerability's exploitation required sophisticated techniques to achieve reliable code execution, but the potential impact made it a high-priority target for attackers seeking persistent access to affected systems. The incident contributed to the broader industry understanding of memory safety issues in runtime environments and influenced security practices around multithreaded application development. Organizations were advised to implement network-based protections, browser security settings, and comprehensive patch management procedures to address this vulnerability and similar memory corruption issues in other software components. The vulnerability also reinforced the importance of maintaining awareness of end-of-life software products, as Flash Player reached end-of-life status in 2020, making it increasingly difficult to obtain security updates for vulnerable installations.