CVE-2018-4872 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 a security bypass vulnerability that leads to a sandbox escape. Specifically, the vulnerability exists in the way a cross call is handled.
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Analysis
by VulDB Data Team • 07/22/2024
Adobe Acrobat Reader contains a critical security bypass vulnerability that enables sandbox escape through improper handling of cross calls in the software's execution environment. This vulnerability affects multiple versions of Adobe Acrobat Reader including 2018.009.20050 and earlier, 2017.011.30070 and earlier, and 2015.006.30394 and earlier releases. The flaw resides in the cross call mechanism that manages communication between different components within the application's sandboxed environment. When processing cross calls, the software fails to properly validate or restrict the execution context, allowing malicious code to bypass the intended security boundaries. This vulnerability represents a significant threat to endpoint security as it enables attackers to escape the restricted sandbox environment where PDF documents are typically executed, thereby gaining access to the underlying operating system. The security bypass occurs at the kernel level where cross call handling does not properly enforce access controls, creating a pathway for privilege escalation. This vulnerability directly relates to CWE-284 which addresses improper access control, and aligns with ATT&CK technique T1068 which covers local privilege escalation through sandbox escapes. The impact of this vulnerability extends beyond simple document viewing as it allows attackers to execute arbitrary code with elevated privileges, potentially leading to complete system compromise. The vulnerability is particularly dangerous because it leverages the legitimate cross call functionality that is essential for PDF processing, making it difficult to detect through traditional security monitoring. Exploitation typically involves crafting a malicious PDF document that triggers the vulnerable cross call handling mechanism, enabling the attacker to execute code outside the normal sandbox boundaries. Organizations using affected versions of Adobe Acrobat Reader face significant risk of targeted attacks that could result in data breaches, system infiltration, and persistent access to compromised endpoints.
The technical implementation of this vulnerability involves the improper validation of cross call parameters within Adobe Reader's JavaScript engine and PDF processing components. When the application processes cross calls between different execution contexts, it fails to properly sanitize input parameters or enforce proper privilege boundaries. This allows an attacker to manipulate the cross call mechanism to execute code with higher privileges than intended. The vulnerability exploits the trust model that exists between different components within the Reader application, where legitimate cross calls are not properly validated against malicious input. The sandbox escape occurs because the cross call handling code does not properly implement access control checks that would normally prevent unauthorized code execution. This flaw creates a pathway for attackers to execute malicious code in a context where they would normally be restricted. The vulnerability can be exploited through crafted PDF files that contain malicious JavaScript or embedded content that triggers the vulnerable code path. The exploitation requires understanding of the underlying cross call mechanism and how to manipulate it to bypass the intended security restrictions. This attack vector represents a sophisticated technique that leverages the application's legitimate functionality to achieve unauthorized access. The vulnerability is particularly challenging to defend against because it operates within the legitimate application execution flow, making it difficult to distinguish between normal and malicious behavior through standard security controls.
Mitigation strategies for this vulnerability require immediate patching of affected Adobe Acrobat Reader versions to address the cross call handling flaw. Organizations should implement strict update policies that ensure all users maintain current versions of the software. Security administrators should consider implementing additional protective measures such as application whitelisting and sandboxing solutions that provide additional layers of defense beyond the Adobe Reader sandbox. Network-based security controls should be enhanced to monitor for suspicious PDF file behaviors and cross call patterns that may indicate exploitation attempts. The implementation of principle of least privilege should be enforced to minimize the impact if exploitation occurs. Regular security assessments should be conducted to identify and remediate similar vulnerabilities in other Adobe products and third-party applications. System administrators should monitor for unusual file access patterns and privilege escalation attempts that may indicate successful exploitation. The vulnerability also highlights the importance of maintaining current security patches and implementing comprehensive vulnerability management programs that address both known and emerging threats. Organizations should also consider implementing endpoint detection and response solutions that can identify and block exploitation attempts targeting this specific vulnerability. Training programs should be developed to educate users about the risks of opening untrusted PDF documents and the importance of keeping software updated. The security community should continue monitoring for similar vulnerabilities in other Adobe products and related software components that may share similar cross call handling mechanisms.