CVE-2017-16390 in Acrobat Reader
Summary
by MITRE
An issue was discovered in Adobe Acrobat and Reader: 2017.012.20098 and earlier versions, 2017.011.30066 and earlier versions, 2015.006.30355 and earlier versions, and 11.0.22 and earlier versions. This vulnerability is an instance of a use after free vulnerability in the JavaScript engine API. The mismatch between an old and a new object can provide an attacker with unintended memory access -- potentially leading to code corruption, control-flow hijack, or an information leak attack. Successful exploitation could lead to arbitrary code execution.
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Analysis
by VulDB Data Team • 01/24/2021
This vulnerability exists within Adobe Acrobat and Reader software across multiple versions including 2017.012.20098 and earlier, 2017.011.30066 and earlier, 2015.006.30355 and earlier, and 11.0.22 and earlier. The issue manifests as a use after free vulnerability within the JavaScript engine API which represents a critical memory safety flaw that can be exploited by malicious actors. The vulnerability stems from improper handling of object lifecycles in the JavaScript interpreter where a freed memory object is still referenced, creating opportunities for attackers to manipulate memory contents and execute arbitrary code. This specific flaw falls under CWE-416 which defines use after free conditions as a well-known memory corruption vulnerability pattern.
The technical implementation of this vulnerability occurs when the JavaScript engine processes certain PDF documents containing maliciously crafted JavaScript code. During normal operation, objects are allocated in memory and eventually freed when no longer needed, but the engine fails to properly track these freed objects. When an attacker can control the allocation and deallocation sequence of objects, they can manipulate memory layout to overwrite critical data structures or function pointers. This memory manipulation creates a control flow hijack opportunity where execution can be redirected to attacker-controlled code. The mismatch between old and new objects in memory allows for information leakage through memory dumps and can lead to code corruption that enables full system compromise.
The operational impact of this vulnerability extends beyond simple code execution to include complete system compromise and data exfiltration capabilities. Attackers exploiting this vulnerability can gain arbitrary code execution privileges on the victim's system, potentially leading to complete compromise of the endpoint. The vulnerability is particularly dangerous because it operates within the PDF processing context, making it easily exploitable through social engineering attacks that deliver malicious PDF documents via email or web downloads. Once exploited, attackers can establish persistent backdoors, steal sensitive information, or use the compromised system as a launching point for further attacks within the network. The vulnerability affects both desktop and mobile versions of Adobe Reader, making it a widespread threat across different platforms.
Mitigation strategies for this vulnerability require immediate patching of affected Adobe Acrobat and Reader versions to address the underlying memory management flaw in the JavaScript engine. Organizations should implement strict document validation policies and restrict PDF file handling to trusted sources only. Network security controls including web proxies and email filtering systems should be configured to scan and block potentially malicious PDF attachments. Additionally, users should be educated about the risks of opening PDF documents from untrusted sources and should be trained to recognize social engineering attempts. The vulnerability demonstrates the importance of proper memory management in software development and highlights the need for regular security audits of complex software components like JavaScript engines. Security teams should also monitor for exploitation attempts through network traffic analysis and implement endpoint detection and response capabilities to identify potential compromise indicators. This vulnerability serves as a reminder of the critical importance of timely patch management and proper input validation in preventing memory corruption exploits that can lead to complete system compromise.