CVE-2024-8839 in PDF-XChange
Summary
by MITRE • 11/23/2024
PDF-XChange Editor JB2 File Parsing Out-Of-Bounds Read Information Disclosure Vulnerability. This vulnerability allows remote attackers to disclose sensitive information on affected installations of PDF-XChange Editor. User interaction is required to exploit this vulnerability in that the target must visit a malicious page or open a malicious file.
The specific flaw exists within the parsing of JB2 files. The issue results from the lack of proper validation of user-supplied data, which can result in a read past the end of an allocated object. An attacker can leverage this in conjunction with other vulnerabilities to execute arbitrary code in the context of the current process. Was ZDI-CAN-24419.
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Analysis
by VulDB Data Team • 03/09/2025
The CVE-2024-8839 vulnerability represents a critical out-of-bounds read condition affecting PDF-XChange Editor's handling of JB2 image files, a format commonly used for embedded graphics within PDF documents. This vulnerability falls under the CWE-125 weakness category, which specifically addresses out-of-bounds read errors that occur when a program reads data beyond the boundaries of allocated memory regions. The flaw manifests during the parsing of JB2 files, which are compressed image formats that store image data in a specific binary structure. When the PDF-XChange Editor processes these files without proper input validation, it fails to verify that all data reads remain within the confines of the allocated buffer, creating an exploitable condition that can be leveraged by malicious actors.
The technical implementation of this vulnerability stems from insufficient bounds checking within the JB2 file parser component of the PDF-XChange Editor application. When processing maliciously crafted JB2 files, the application attempts to read memory locations beyond the intended data boundaries, potentially exposing sensitive information from adjacent memory regions. This memory corruption issue creates opportunities for information disclosure attacks where attackers can extract confidential data such as stack contents, heap memory values, or other sensitive information that may contain authentication tokens, cryptographic keys, or system configuration details. The vulnerability's classification aligns with the ATT&CK technique T1059.007 for command and scripting interpreter, as the information disclosure can provide attackers with the necessary data to craft more sophisticated attacks or escalate privileges within the compromised system.
The operational impact of this vulnerability extends beyond simple information disclosure, as it creates a potential pathway for more severe exploitation techniques. While the immediate effect involves reading beyond allocated memory boundaries, the underlying flaw can serve as a stepping stone for attackers to establish persistent access or execute arbitrary code within the context of the PDF-XChange Editor process. The requirement for user interaction through visiting malicious web pages or opening compromised files aligns with the ATT&CK tactic T1203 for legitimate credentials, as successful exploitation may lead to credential exposure or privilege escalation. Attackers can leverage this vulnerability to gather intelligence about the target system's memory layout, which can be instrumental in developing more sophisticated exploitation strategies that bypass modern security protections such as ASLR and DEP. The vulnerability's presence in the PDF-XChange Editor application creates a persistent threat vector that can be exploited across different operating systems where the software is installed, making it particularly dangerous in enterprise environments where PDF processing is common.
Mitigation strategies for CVE-2024-8839 should focus on both immediate patching and operational security measures. Organizations must prioritize updating their PDF-XChange Editor installations to the latest versions that contain fixes for the JB2 parsing vulnerability, as this represents the most direct approach to eliminating the threat. Additionally, implementing network-based controls such as web application firewalls and content filtering solutions can help prevent users from accessing malicious pages that might contain exploit payloads. The principle of least privilege should be enforced by restricting user access to PDF-XChange Editor functionality and implementing sandboxing techniques to limit the potential impact of successful exploitation attempts. Security monitoring should include detection of unusual file parsing activities or memory access patterns that might indicate exploitation attempts. Regular security assessments of PDF processing capabilities and input validation mechanisms should be conducted to identify similar vulnerabilities in other document processing components, as the underlying architectural issues that enable this vulnerability may exist in other parts of the application or related software components.