CVE-2018-4911 in Acrobat Reader
Summary
by MITRE
An issue was discovered in Adobe Acrobat Reader 2018.009.20050 and earlier versions, 2017.011.30070 and earlier versions, 2015.006.30394 and earlier versions. This vulnerability is an instance of a use after free vulnerability in the JavaScript API related to bookmark functionality. The vulnerability is triggered by crafted JavaScript code embedded within a PDF file. A successful attack can lead to code corruption, control-flow hijack, or a code re-use attack.
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Analysis
by VulDB Data Team • 07/22/2024
The vulnerability identified as CVE-2018-4911 represents a critical use after free flaw within Adobe Acrobat Reader's JavaScript API implementation, specifically affecting bookmark functionality. This issue manifests in multiple product versions including 2018.009.20050 and earlier, 2017.011.30070 and earlier, and 2015.006.30394 and earlier releases. The flaw stems from improper memory management within the JavaScript engine when processing bookmark-related API calls, creating conditions where freed memory blocks can be accessed and reused by subsequent operations. The vulnerability falls under CWE-416, which specifically addresses use after free conditions, and aligns with ATT&CK technique T1059.007 for JavaScript-based execution. This memory corruption vulnerability demonstrates how seemingly benign PDF bookmark functionality can serve as a vector for more severe exploitation.
The exploitation mechanism relies on crafting malicious JavaScript code embedded within PDF documents that triggers the vulnerable bookmark API functions. When a user opens a specially crafted PDF file, the malicious JavaScript code executes and causes the application to free memory associated with bookmark objects while simultaneously allowing subsequent code to reference that freed memory. This creates a window where attackers can manipulate memory contents, potentially leading to arbitrary code execution. The attack vector demonstrates the classic use after free exploitation pattern where an attacker can corrupt memory structures, hijack control flow, or perform code re-use attacks by overwriting function pointers or other critical memory locations that were previously allocated to bookmark objects.
The operational impact of this vulnerability extends beyond simple code execution, as it provides attackers with significant control over the target system. Successful exploitation can result in complete system compromise, allowing attackers to execute arbitrary commands with the privileges of the Acrobat Reader process. The vulnerability's presence in widely deployed versions of Acrobat Reader means that any user opening malicious PDF files could become a victim, creating substantial risk for enterprise environments where PDF documents are frequently shared. This type of vulnerability is particularly dangerous because it can be delivered through email attachments or web downloads, making it a common vector for initial access in targeted attacks. The control-flow hijacking capability means that attackers can redirect program execution to payload code, potentially leading to data exfiltration, persistence mechanisms, or further exploitation of the compromised system.
Mitigation strategies for CVE-2018-4911 should prioritize immediate patching of affected Adobe Acrobat Reader versions to the latest security updates. Organizations should implement strict PDF file validation policies, including sandboxing PDF processing environments and restricting JavaScript execution in PDF documents. Network-based defenses should include PDF content filtering and deep packet inspection to identify potentially malicious PDF files before they reach end users. Additionally, user education regarding the dangers of opening untrusted PDF files remains critical, as social engineering often plays a role in delivering these malicious documents. Security teams should monitor for indicators of compromise related to this vulnerability, including unusual network connections or file access patterns that might indicate exploitation attempts. The vulnerability highlights the importance of maintaining up-to-date security patches and implementing defense-in-depth strategies to protect against zero-day exploits that leverage memory corruption vulnerabilities in widely used applications.