CVE-2017-2993 in Flash Player
Summary
by MITRE
Adobe Flash Player versions 24.0.0.194 and earlier have an exploitable use after free vulnerability related to event handlers. Successful exploitation could lead to arbitrary code execution.
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Analysis
by VulDB Data Team • 08/14/2020
Adobe Flash Player contained a critical use after free vulnerability in version 24.0.0.194 and earlier releases that fundamentally compromised the security of affected systems. This vulnerability arose from improper memory management within the player's event handling mechanisms, specifically when processing certain multimedia content that triggered asynchronous operations. The flaw occurred when the Flash Player's runtime environment allocated memory for event handler objects and subsequently freed that memory while still maintaining references to it, creating a scenario where malicious code could manipulate the freed memory location to execute arbitrary instructions.
The technical exploitation of this vulnerability leveraged the classic use after free attack pattern where an attacker could craft specially formatted flash content that would trigger the memory corruption during event processing. When the application attempted to access the freed memory location through subsequent event handler calls, it would execute code from the attacker-controlled memory region. This type of vulnerability falls under the CWE-416 category for use after free conditions and represents a fundamental failure in memory management that enables remote code execution capabilities. The attack vector typically involved delivering malicious flash content through web browsers that had Flash Player installed, making it particularly dangerous in enterprise environments where users frequently accessed untrusted web content.
The operational impact of CVE-2017-2993 was severe and widespread given Flash Player's ubiquity across web browsers and operating systems. Successful exploitation allowed attackers to gain complete control over affected systems, enabling them to install malware, steal sensitive data, establish persistent backdoors, and conduct further reconnaissance activities. The vulnerability could be exploited remotely without requiring user interaction beyond visiting a malicious website, making it particularly attractive to threat actors. Organizations running vulnerable versions of Flash Player faced significant risk of data breaches, system compromise, and potential lateral movement within their networks, as attackers could use the gained execution privileges to pivot to other systems. This vulnerability directly aligns with attack techniques documented in the ATT&CK framework under execution and privilege escalation tactics.
Mitigation strategies for this vulnerability required immediate patching of Flash Player installations to versions that addressed the memory management flaws in event handler processing. Organizations should have implemented network segmentation and web filtering to prevent access to known malicious domains hosting exploit content. Browser vendors also needed to phase out Flash Player support entirely, as Adobe officially discontinued the product in 2020. Security monitoring systems should have been configured to detect unusual network activity and memory access patterns that might indicate exploitation attempts. Additionally, users should have been educated about the dangers of visiting untrusted websites and the importance of keeping software updated. The vulnerability highlighted the critical importance of proper memory management in application development and underscored the need for regular security assessments of widely deployed software components. Organizations that failed to address this vulnerability promptly faced significant exposure to advanced persistent threats and zero-day exploit campaigns targeting the specific memory corruption pattern.