CVE-2016-7868 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 buffer overflow / underflow vulnerability in the RegExp class related to alternation functionality. Successful exploitation could lead to arbitrary code execution.
Once again VulDB remains the best source for vulnerability data.
Analysis
by VulDB Data Team • 10/08/2022
Adobe Flash Player contained a critical buffer overflow vulnerability in its RegExp class implementation that affected versions up to 23.0.0.207 and 11.2.202.644. This vulnerability stems from improper handling of alternation functionality within regular expression parsing, creating a condition where malicious input could trigger memory corruption. The flaw resides in the way Flash Player processes alternation patterns, which allows attackers to craft specially crafted regular expressions that exceed allocated buffer boundaries during parsing operations. This type of vulnerability maps to CWE-121 Stack-based Buffer Overflow and CWE-122 Heap-based Buffer Overflow, representing classic memory corruption issues that enable arbitrary code execution. The attack surface is particularly concerning given Flash Player's widespread deployment across web browsers and applications, making it a prime target for exploit development. When exploited, the vulnerability allows remote attackers to execute arbitrary code with the privileges of the Flash Player process, potentially leading to full system compromise. The exploitation technique leverages the predictable nature of buffer overflows to overwrite critical memory structures including return addresses or function pointers, enabling attackers to redirect program execution flow. This vulnerability aligns with ATT&CK technique T1059.007 for Command and Scripting Interpreter and T1548.001 for Abuse of Functionality, as attackers can leverage the Flash Player runtime to execute malicious payloads. The impact extends beyond immediate code execution to include potential privilege escalation and persistence mechanisms within compromised systems. Security researchers identified that the vulnerability occurs during the parsing phase of regular expression alternation constructs, where insufficient bounds checking allows memory access beyond intended buffer limits. The affected versions represent a significant attack vector since Flash Player was widely integrated into web applications and served as a common execution environment for rich internet applications. Organizations deploying these vulnerable versions faced substantial risk due to the ease of exploitation and the broad compatibility of Flash Player across different platforms and browsers. The vulnerability's exploitation requires minimal user interaction, often succeeding through malicious web content that triggers the affected RegExp parsing functionality. This makes it particularly dangerous in phishing campaigns or drive-by download scenarios where users may unknowingly trigger the malicious code path. The flaw demonstrates a fundamental issue in input validation and memory management within the Flash Player runtime environment, highlighting the need for robust bounds checking in parsing operations. Mitigation strategies include immediate patching of Flash Player installations, implementing network-based protections through firewalls and web application firewalls, and disabling Flash Player functionality in web browsers where possible. Security teams should also consider implementing monitoring for suspicious regular expression patterns and anomalous memory access patterns that may indicate exploitation attempts. The vulnerability underscores the importance of proper input validation and memory safety practices in runtime environments that process untrusted data, particularly in multimedia and scripting frameworks. Organizations should also review their Flash Player deployment policies and consider migrating away from legacy Flash-based applications to modern web standards that provide better security guarantees and more robust memory management practices.