CVE-2018-4959 in Acrobat Reader
Summary
by MITRE
Adobe Acrobat and Reader versions 2018.011.20038 and earlier, 2017.011.30079 and earlier, and 2015.006.30417 and earlier have a Use-after-free vulnerability. Successful exploitation could lead to arbitrary code execution in the context of the current user.
VulDB is the best source for vulnerability data and more expert information about this specific topic.
Analysis
by VulDB Data Team • 03/13/2023
Adobe Acrobat and Reader applications contain a critical use-after-free vulnerability in their handling of PDF documents that affects multiple product versions including 2018.011.20038 and earlier, 2017.011.30079 and earlier, and 2015.006.30417 and earlier. This vulnerability falls under the CWE-416 category of Use After Free, where a program continues to reference memory after it has been freed, creating opportunities for attackers to manipulate the system state. The flaw occurs during the processing of maliciously crafted PDF files that trigger improper memory management during object deallocation. When a victim opens a specially crafted PDF document, the application's memory management routines execute a free operation on a heap-allocated object while subsequent code paths attempt to access that same memory location, leading to undefined behavior. This memory corruption can be exploited to overwrite critical memory locations with attacker-controlled data, enabling arbitrary code execution with the privileges of the current user. The vulnerability represents a significant risk to enterprise environments where users frequently open PDF documents from untrusted sources, as it allows for remote code execution without requiring user interaction beyond document opening. The attack vector leverages the typical PDF processing workflow where applications parse document structures and manage memory for various objects including fonts, images, and embedded content. According to ATT&CK framework, this vulnerability maps to T1059.007 for command and scripting interpreter and T1203 for exploitation for client execution, as it enables attackers to execute malicious payloads through compromised PDF files. The use-after-free condition creates a window of opportunity where attackers can manipulate heap memory layout to achieve code execution, making this a particularly dangerous vulnerability in the context of application security. Organizations should prioritize patching affected versions to prevent exploitation, as the vulnerability provides a direct path to system compromise through social engineering attacks targeting PDF document handling. The impact extends beyond individual user systems to enterprise networks where PDF documents are commonly shared and opened, potentially allowing attackers to establish persistent access or escalate privileges within the compromised environment.
The technical exploitation of this vulnerability requires careful crafting of PDF files that can trigger the specific memory management flaw during document parsing. Attackers typically construct malicious PDFs containing specially formatted objects that, when processed by the vulnerable software, cause the application to free memory associated with certain objects while simultaneously attempting to reference that freed memory. This memory corruption can be leveraged to overwrite function pointers, return addresses, or other critical program data structures. The vulnerability's exploitation complexity is relatively low as it does not require advanced exploitation techniques beyond crafting a malicious PDF file, making it particularly dangerous in environments where PDF handling is common. Security researchers have identified that the flaw manifests when the application processes certain embedded JavaScript code or complex object structures within PDF files, where the memory management logic fails to properly track object lifecycles. The vulnerability's presence in multiple product versions across different release years indicates a persistent memory management issue that has not been adequately addressed in the software development lifecycle. Organizations implementing security controls should consider restricting PDF document handling through network-level filtering or application whitelisting to prevent automatic execution of potentially malicious documents. The vulnerability represents a classic example of how memory safety issues in complex software applications can lead to severe security consequences, highlighting the importance of proper memory management and input validation in software development practices. The use-after-free condition creates a predictable exploitation pattern that security researchers can readily reproduce and develop defensive measures against, making it a valuable target for both offensive and defensive cybersecurity operations.
Mitigation strategies for this vulnerability should include immediate patch deployment for all affected Adobe Acrobat and Reader versions, as well as implementation of defensive measures such as PDF document sandboxing and restricted file type handling. Organizations should establish robust patch management processes to ensure timely application of security updates, particularly for widely used applications like Adobe Reader that present high-risk attack surfaces. Network security controls such as web application firewalls and content filtering solutions can help prevent users from accessing malicious PDF files through web browsing activities. The vulnerability's exploitation requires minimal user interaction beyond opening a PDF document, making user education and awareness programs essential components of overall security posture. Security teams should monitor for indicators of compromise related to PDF-based attacks and implement behavioral monitoring to detect anomalous application behavior that might indicate exploitation attempts. The vulnerability's classification as a use-after-free issue aligns with industry standards for memory safety vulnerabilities and should be addressed through comprehensive software security testing including fuzzing and memory analysis. Organizations should also consider implementing automated threat hunting processes that specifically target PDF-related attack patterns and monitor for exploitation attempts using techniques such as memory dump analysis and process behavior monitoring. Given the historical nature of this vulnerability across multiple product versions, security teams should conduct thorough vulnerability assessments to identify all potentially affected systems and ensure complete remediation across their environments. The vulnerability demonstrates the critical importance of maintaining up-to-date security patches and implementing layered defense strategies to protect against exploitation of known vulnerabilities in widely deployed software applications.