CVE-2016-7869 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 backtrack search functionality. Successful exploitation could lead to arbitrary code execution.
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Analysis
by VulDB Data Team • 10/08/2022
Adobe Flash Player contains a critical buffer overflow vulnerability in its RegExp class implementation that stems from improper handling of backtrack search functionality during regular expression processing. This vulnerability affects versions 23.0.0.207 and earlier, as well as 11.2.202.644 and earlier, making it a widespread issue across multiple Flash Player releases. The flaw occurs when the player processes specially crafted regular expressions that trigger excessive memory allocation during backtracking operations, leading to buffer overflows that can be exploited by malicious actors.
The technical implementation of this vulnerability resides in the RegExp class's backtrack search algorithm where insufficient bounds checking occurs during memory allocation for intermediate results. When processing complex regular expressions with nested quantifiers and backreferences, the parser allocates memory without adequate validation of the required buffer size, resulting in memory corruption that can be leveraged for code execution. This type of vulnerability maps directly to CWE-121, which describes heap-based buffer overflow conditions, and represents a classic example of unsafe memory handling in interpreted environments.
The operational impact of this vulnerability extends beyond simple code execution to encompass full system compromise when exploited in the context of web browsers or other applications that embed Flash Player. Attackers can craft malicious web pages containing specially constructed regular expressions that, when processed by the vulnerable Flash Player, trigger the buffer overflow condition. This creates a significant attack surface since Flash Player was widely deployed across web browsers and enabled by default in most environments, making exploitation relatively straightforward for threat actors.
Security practitioners should implement immediate mitigations including disabling Flash Player in web browsers, updating to patched versions of Flash Player, and deploying network-based intrusion detection systems to monitor for exploitation attempts. The vulnerability demonstrates the importance of proper bounds checking in interpreted languages and highlights the risks associated with legacy software components that continue to receive updates but remain widely deployed. Organizations should also consider implementing application whitelisting policies to prevent execution of vulnerable Flash content and regularly audit their software inventory for deprecated technologies that pose ongoing security risks. This vulnerability exemplifies ATT&CK technique T1059.007 for application execution and T1203 for exploitation of remote services, making it a critical target for defensive measures in enterprise security environments.