CVE-2020-16309 in Ghostscript
Summary
by MITRE
A buffer overflow vulnerability in lxm5700m_print_page() in devices/gdevlxm.c of Artifex Software GhostScript v9.50 allows a remote attacker to cause a denial of service via a crafted eps file. This is fixed in v9.51.
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Analysis
by VulDB Data Team • 08/13/2020
The buffer overflow vulnerability identified as CVE-2020-16309 resides within the GhostScript document processing library, specifically in the lxm5700m_print_page() function located in devices/gdevlxm.c. This flaw represents a critical security weakness that enables remote attackers to execute denial of service attacks through manipulation of eps file inputs. Artifex Software GhostScript version 9.50 contains this vulnerability, which was subsequently addressed in version 9.51. The vulnerability occurs during the processing of PostScript and PDF documents where the software fails to properly validate input data before performing buffer operations. The affected function processes print page operations for the lxm5700m device driver, which is designed for laser printing capabilities and handles various document formats including encapsulated postscript files.
The technical exploitation of this buffer overflow stems from improper bounds checking within the device driver implementation. When GhostScript processes a crafted eps file, the lxm5700m_print_page() function attempts to write data to a buffer without adequate validation of input parameters. This allows an attacker to supply malicious input that exceeds the allocated buffer size, causing memory corruption and system instability. The vulnerability manifests as a classic stack-based buffer overflow condition where the excessive data overwrite can lead to program termination, memory corruption, or potentially arbitrary code execution depending on the system configuration. This type of vulnerability is categorized under CWE-121 as Stack-based Buffer Overflow, which directly impacts the software's memory management and execution flow.
Operationally, this vulnerability presents significant risks to organizations relying on GhostScript for document processing and rendering. Remote attackers can exploit this weakness by simply providing a malicious eps file to any system running vulnerable GhostScript versions, making it particularly dangerous in web environments or document handling systems. The denial of service impact can disrupt business operations, particularly in environments where document processing is critical such as print servers, automated document workflows, or enterprise content management systems. The vulnerability is particularly concerning because it requires no special privileges or authentication to exploit, making it accessible to anyone capable of delivering the malicious file. Organizations using GhostScript for document conversion, printing, or rendering services are exposed to potential service disruption and may face operational downtime during exploitation attempts.
Mitigation strategies for CVE-2020-16309 primarily involve immediate patching to version 9.51 or later, which contains the necessary fixes for the buffer overflow condition. System administrators should prioritize updating all GhostScript installations across their infrastructure, particularly in environments where the software processes untrusted document inputs. Additional protective measures include implementing strict input validation for eps files, deploying network segmentation to limit access to vulnerable systems, and establishing monitoring for suspicious document processing activities. The vulnerability aligns with ATT&CK technique T1203 as Exploitation for Execution, where attackers leverage software vulnerabilities to gain unauthorized access or disrupt system operations. Organizations should also consider implementing sandboxing techniques for document processing and maintaining regular vulnerability assessments to identify similar issues in their software stacks. Given the nature of the flaw, it is essential to maintain up-to-date security patches and conduct regular security audits of document processing systems to prevent exploitation attempts.