CVE-2018-15982

What is Adobe Flash Player?

Adobe Flash Player was, for years, one of the most widely installed browser plugins in the world, used to render interactive animations, video, and rich web content. Its long history of memory-corruption vulnerabilities made it one of the most commonly weaponized attack surfaces for both cybercrime and nation-state actors throughout the 2010s, ultimately contributing to Adobe's decision to fully end-of-life the product on December 31, 2020.

Overview

CVE-2018-15982 is a use-after-free vulnerability in Adobe Flash Player's com.adobe.tvsdk.mediacore.metadata component that was discovered being actively exploited in the wild as a zero-day before a patch was available. Attackers embedded a malicious Flash object inside a Microsoft Office document, which, when opened, triggered the use-after-free to execute attacker-controlled code on the victim's machine.

Technical Details

The flaw (CWE-416, Use After Free) occurs when the vulnerable metadata-handling code in Flash's media core continues to reference a memory object after it has been freed, allowing an attacker who controls the timing and contents of that freed memory to hijack program execution and run arbitrary code with the privileges of the user running Flash Player — typically inside a browser or embedded in an Office document viewer. Exploitation requires user interaction (opening a malicious document or visiting a page with the crafted Flash content), rated CVSS 7.8 (local vector reflecting execution in the context of the user session, low complexity).

Discovery

The zero-day exploitation was discovered in the wild by researchers at Gigamon Applied Threat Research (ATR) and independently by Qihoo 360's Threat Intelligence Center, who identified a malicious Office document targeting a Russian government-linked medical/healthcare research organization. Adobe credited these findings and issued an emergency out-of-band patch shortly after.

Exploitation Context

This vulnerability was exploited as a zero-day in a targeted espionage-style campaign before any patch existed, delivered via a booby-trapped Word document containing an embedded Flash ActiveX object — a well-established delivery method for Flash exploits at the time. Its inclusion in CISA's KEV catalog, years after Flash Player's end-of-life, reflects that unpatched legacy systems still running Flash (embedded in old documents, kiosks, or industrial/embedded systems) remain viable targets for this exploit long after the plugin's official retirement.

Remediation

1. Since Adobe fully discontinued Flash Player on December 31, 2020, the only complete remediation is uninstalling Flash Player entirely from all systems.
2. Identify and remove any legacy applications, kiosks, or embedded systems that still bundle or require Flash Player.
3. Block Flash/SWF content execution at the browser and email gateway level for any systems that cannot immediately remove the plugin.
4. Treat any Office document containing embedded Flash/ActiveX content as high-risk and inspect it before opening, especially from external senders.
5. Prioritize migrating any remaining Flash-dependent business processes to modern, supported technology.