CVE-2007-6725 in Ghostscript
Summary
by MITRE
The CCITTFax decoding filter in Ghostscript 8.60, 8.61, and possibly other versions, allows remote attackers to cause a denial of service (crash) and possibly execute arbitrary code via a crafted PDF file that triggers a buffer underflow in the cf_decode_2d function.
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Analysis
by VulDB Data Team • 09/01/2019
The vulnerability identified as CVE-2007-6725 represents a critical security flaw in the Ghostscript PDF processing library that affects versions 8.60 and 8.61, with potential impacts extending to other releases in the same series. This issue resides within the CCITTFax decoding filter component, which is responsible for handling fax compression data within PDF documents. The flaw manifests when processing specially crafted PDF files that contain malformed CCITTFax data, leading to a buffer underflow condition in the cf_decode_2d function. This type of vulnerability falls under the category of memory safety issues and is particularly dangerous due to its potential for both denial of service and remote code execution capabilities. The buffer underflow occurs when the decoding process attempts to read beyond the allocated memory boundaries, creating conditions that can be exploited by malicious actors to disrupt system operations or gain unauthorized access to affected systems.
The technical exploitation of this vulnerability requires an attacker to craft a malicious PDF file containing specific CCITTFax compression data that triggers the buffer underflow condition within the cf_decode_2d function. This function processes two-dimensional CCITTFax data and performs decoding operations that assume proper data boundaries and structure. When malformed data is encountered, the function fails to properly validate input parameters, leading to memory corruption that can result in program crashes or more severe consequences. The vulnerability is classified as a buffer underflow rather than a buffer overflow, which is significant because it indicates that the program attempts to read data from memory locations that are before the allocated buffer rather than after them. This distinction is important for understanding the exploitation mechanics and developing appropriate defensive measures. The weakness directly relates to CWE-121, which describes heap-based buffer overflow conditions, and may also connect to broader categories of memory corruption vulnerabilities that are frequently targeted by attackers.
The operational impact of this vulnerability extends beyond simple denial of service scenarios to encompass potential remote code execution capabilities that could compromise entire systems. When a victim system processes a malicious PDF file through Ghostscript, the buffer underflow can cause the application to crash or behave unpredictably, leading to service disruption that affects users and potentially enabling more sophisticated attacks. The remote exploitation aspect means that attackers do not need physical access to the target system, allowing them to deliver malicious payloads through email attachments, web downloads, or other network-based delivery mechanisms. This vulnerability is particularly concerning for organizations that rely on PDF processing for document management, as it creates attack vectors through legitimate document handling processes. The potential for arbitrary code execution places this vulnerability in the ATT&CK framework under the T1059 category of Command and Scripting Interpreter, as successful exploitation could enable attackers to execute malicious commands within the context of the affected system.
Organizations affected by this vulnerability should implement immediate mitigations to protect their systems from potential exploitation. The most effective approach involves upgrading to a patched version of Ghostscript that addresses the buffer underflow condition in the cf_decode_2d function. Additionally, administrators should implement strict PDF file validation processes that can identify and quarantine suspicious files before they are processed by Ghostscript. Network-based security controls such as web application firewalls and content filtering systems can help prevent malicious PDF files from reaching end users. The implementation of sandboxing techniques for PDF processing can also provide additional protection layers by isolating the processing environment from critical system resources. Security monitoring should be enhanced to detect unusual Ghostscript process behavior or memory access patterns that might indicate exploitation attempts. Organizations should also consider implementing least privilege principles for PDF processing applications to limit the potential impact of successful exploitation attempts. This vulnerability highlights the importance of maintaining up-to-date software libraries and implementing comprehensive security practices that address both known vulnerabilities and emerging threats in document processing systems.