Adobe Flash Player Use-After-Free Remote Code Execution (RCE) Vulnerability (CVE-2016-7855) Security Advisory

1. Vulnerability Overview & Root Cause

This vulnerability (CVE-2016-7855) is a critical Use-After-Free (UAF) flaw in Adobe Flash Player. It occurs when the application continues to reference a memory pointer after the corresponding object has been deallocated from memory. Due to improper state management in the Flash engine, an attacker can manipulate the memory layout to reuse the freed memory space for malicious payloads.

2. Exploitation Mechanics & Attack Scenario

An attacker exploits this vulnerability by hosting a specially crafted SWF (Shockwave Flash) file on a malicious website or distributing it via email attachments. When a victim opens the file, the Flash Player engine parses the malicious ActionScript, triggering premature object destruction. The attacker then fills the freed memory slot with controlled shellcode. When the engine attempts to reuse the dangling pointer, execution flow is redirected to the attacker's shellcode, achieving Remote Code Execution (RCE). This vulnerability was actively exploited in the wild in October 2016.

3. Infrastructure & Business Impact

Successful exploitation allows an attacker to gain full control of the compromised endpoint. This can serve as an initial entry point into the corporate network, leading to lateral movement, sensitive data exfiltration, or ransomware deployment. Given its active exploitation history and inclusion in the CISA KEV catalog, this vulnerability poses a severe risk to legacy environments.