CVE-2016-7877 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 use after free vulnerability in the Action Message Format serialization (AFM0). Successful exploitation could lead to arbitrary code execution.
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Analysis
by VulDB Data Team • 10/08/2022
The CVE-2016-7877 vulnerability represents a critical use after free flaw in Adobe Flash Player's Action Message Format serialization implementation. This vulnerability specifically affects Flash Player versions 23.0.0.207 and earlier, as well as version 11.2.202.644 and earlier, making it a long-standing issue that impacted a substantial portion of Flash Player installations across multiple versions. The vulnerability resides within the AFM0 serialization mechanism, which is responsible for handling Action Message Format data structures commonly used in Flash applications and web communications. This particular flaw allows attackers to manipulate memory references after objects have been freed, creating opportunities for malicious code execution through carefully crafted Flash content.
The technical exploitation of this vulnerability involves leveraging the improper memory management within the AFM0 deserialization process to trigger a use after free condition. When Flash Player processes malicious Action Message Format data, it can cause memory allocated to objects to be freed while references to those objects remain accessible. Attackers can then manipulate this freed memory to overwrite critical data structures or inject executable code, ultimately achieving arbitrary code execution on the target system. This type of vulnerability falls under the CWE-416 category of use after free conditions, which represents a fundamental memory safety issue that has been a persistent concern in software development. The exploitation technique typically involves creating specially crafted Flash content that triggers the vulnerable code path during deserialization operations.
From an operational perspective, this vulnerability presents significant risks to organizations relying on Flash Player for web content delivery and interactive applications. The impact extends beyond individual user systems to potentially compromise entire network infrastructures, as successful exploitation can lead to complete system compromise. The vulnerability's exploitation requires minimal user interaction, often only visiting a malicious webpage or opening a specially crafted Flash file, making it particularly dangerous in phishing campaigns or drive-by download attacks. The widespread adoption of Flash Player across various web applications and the relatively low barrier to exploitation make this vulnerability particularly attractive to threat actors seeking to establish persistent access to target systems. Security researchers have noted that this vulnerability aligns with ATT&CK technique T1059.007 for command and script interpreter, as the arbitrary code execution capability enables attackers to deploy additional malicious payloads or establish backdoors.
Mitigation strategies for CVE-2016-7877 primarily focus on immediate remediation through Adobe's security patches and updates, as well as operational security measures to reduce exposure. Organizations should prioritize updating all Flash Player installations to versions that address this vulnerability, though the end-of-life status of Flash Player complicates this process. System administrators should implement network-based controls such as web application firewalls and content filtering solutions to block malicious Flash content, while also considering browser-level restrictions that disable Flash plugin execution. The vulnerability's classification as a critical security issue warrants immediate attention in vulnerability management programs, with regular monitoring for similar memory corruption flaws in other software components. Additionally, organizations should consider implementing application whitelisting policies and sandboxing mechanisms to limit the potential impact of successful exploitation attempts, as these controls can provide defense-in-depth measures against similar use after free vulnerabilities.