CVE-2016-0994 in Flash Player
Summary
by MITRE
Use-after-free vulnerability in Adobe Flash Player before 18.0.0.333 and 19.x through 21.x before 21.0.0.182 on Windows and OS X and before 11.2.202.577 on Linux, Adobe AIR before 21.0.0.176, Adobe AIR SDK before 21.0.0.176, and Adobe AIR SDK & Compiler before 21.0.0.176 allows attackers to execute arbitrary code by using the actionCallMethod opcode with crafted arguments, a different vulnerability than CVE-2016-0987, CVE-2016-0988, CVE-2016-0990, CVE-2016-0991, CVE-2016-0995, CVE-2016-0996, CVE-2016-0997, CVE-2016-0998, CVE-2016-0999, and CVE-2016-1000.
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Analysis
by VulDB Data Team • 07/10/2022
The vulnerability described in CVE-2016-0994 represents a critical use-after-free flaw in Adobe Flash Player and Adobe AIR runtime environments across multiple platforms and versions. This vulnerability specifically affects Flash Player versions prior to 18.0.0.333 and 19.x through 21.x before 21.0.0.182 on Windows and OS X systems, while Linux versions are impacted before 11.2.202.577. Additionally, Adobe AIR runtime environments and related SDKs prior to version 21.0.0.176 are vulnerable to this same issue. The flaw manifests through the actionCallMethod opcode when processing crafted arguments, making it particularly dangerous as it can be exploited remotely through web browsers that have Flash Player enabled. This vulnerability operates under the broader category of memory corruption issues that fall under CWE-416, which specifically addresses use-after-free conditions where program code continues to reference memory locations after they have been freed, leading to unpredictable behavior and potential code execution.
The technical exploitation of this vulnerability involves manipulating the Flash Player's bytecode execution engine through the actionCallMethod opcode, which is responsible for calling methods on objects within the Flash runtime. When attackers provide specially crafted arguments to this opcode, they can trigger a scenario where memory allocated for an object is freed while the application still maintains references to it. This creates a situation where subsequent operations on the freed memory can be manipulated to overwrite critical program data or execute arbitrary code. The vulnerability is particularly concerning because it leverages the legitimate Flash Player functionality to create a memory corruption state that attackers can then exploit to gain control over the affected system. The exploitation requires no user interaction beyond visiting a malicious webpage that loads the crafted Flash content, making it particularly dangerous for widespread deployment. This attack pattern aligns with ATT&CK technique T1059.007, which covers the use of scripting languages like ActionScript that Flash Player supports, and represents a classic example of how legitimate runtime features can be abused to create privilege escalation opportunities.
The operational impact of CVE-2016-0994 extends far beyond simple code execution, as it provides attackers with the ability to completely compromise affected systems. Once successfully exploited, attackers can gain full system control, potentially leading to data theft, system monitoring, or further lateral movement within networks. The vulnerability affects a wide range of systems since Flash Player was widely deployed across both enterprise and consumer environments, making it an attractive target for cybercriminals. The fact that this vulnerability affects multiple versions of Adobe AIR and its SDKs means that developers and organizations using these tools are also at risk, particularly those who may be unaware of the specific version requirements for protection. Organizations with legacy systems that still rely on older Flash Player versions face particularly high risk, as these systems often lack the security updates and modern protection mechanisms that would otherwise mitigate such attacks. The vulnerability's classification as a remote code execution flaw means that attackers can exploit it without requiring physical access to target systems, making it particularly dangerous for enterprise environments where web browsing is a common activity across all user accounts.
Mitigation strategies for CVE-2016-0994 should focus on immediate remediation through patching and updating to supported versions of Adobe Flash Player and Adobe AIR runtime environments. Organizations should prioritize updating all affected systems to versions that contain the necessary security fixes, particularly since Adobe officially ended support for Flash Player in 2020, making continued use of vulnerable versions extremely dangerous. Network-level protections such as content filtering and web application firewalls can provide additional defense-in-depth measures, though these are not substitutes for proper patch management. Security teams should implement monitoring for exploitation attempts, particularly looking for suspicious Flash Player activity or attempts to access deprecated Flash functionality. Given the nature of the vulnerability and its relationship to memory corruption issues, organizations should also consider implementing exploit protection mechanisms and runtime application control policies that prevent execution of untrusted Flash content. The remediation approach should also include comprehensive inventory management to identify all systems running vulnerable versions of Flash Player and Adobe AIR, as well as regular vulnerability scanning to detect any remaining instances of the affected software. Due to the widespread nature of Flash Player deployments and the difficulty in completely removing all Flash content from systems, organizations should also consider implementing user education programs to reduce exposure through social engineering attacks that might leverage this vulnerability.