CVE-2017-7207 in Ghostscript
Summary
by MITRE
The mem_get_bits_rectangle function in Artifex Software, Inc. Ghostscript 9.20 allows remote attackers to cause a denial of service (NULL pointer dereference) via a crafted PostScript document.
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Analysis
by VulDB Data Team • 11/14/2022
The vulnerability identified as CVE-2017-7207 resides within the mem_get_bits_rectangle function of Ghostscript version 9.20, a widely deployed PostScript and PDF interpreter developed by Artifex Software Inc. This flaw represents a critical denial of service condition that can be exploited remotely through maliciously crafted PostScript documents, potentially disrupting the operation of systems that process or render such content. The vulnerability specifically manifests as a NULL pointer dereference, a common class of software defect that occurs when a program attempts to access memory through a pointer that has not been properly initialized or has been set to NULL, leading to system crashes or unexpected termination of the affected application.
The technical implementation of this vulnerability stems from inadequate input validation within the mem_get_bits_rectangle function, which is responsible for handling bitmap data extraction from PostScript documents. When processing specially constructed PostScript files, the function fails to properly validate pointer references before dereferencing them, creating an execution path where a NULL pointer is accessed. This condition violates fundamental software safety principles and can be triggered by any user or application that feeds malformed PostScript content to the vulnerable Ghostscript interpreter. The flaw operates at the intersection of memory management and input processing, where insufficient bounds checking and null pointer validation creates an exploitable condition that can be remotely leveraged.
From an operational perspective, this vulnerability poses significant risks to organizations that rely on Ghostscript for document processing, rendering, or printing operations. Systems running Ghostscript 9.20 may experience unexpected service interruptions when processing untrusted PostScript documents, potentially affecting print servers, document conversion services, or any application that integrates Ghostscript for rasterization tasks. The remote attack vector means that adversaries can exploit this weakness without requiring physical access to the target system, making it particularly dangerous in networked environments where document processing services are exposed to external inputs. This vulnerability can be especially problematic in enterprise settings where automated document processing pipelines may be vulnerable to malicious input, leading to cascading service disruptions and potential business impact.
Mitigation strategies for CVE-2017-7207 should prioritize immediate patching of affected Ghostscript installations to version 9.21 or later, where the NULL pointer dereference has been resolved through proper input validation and pointer initialization. Organizations should implement comprehensive input sanitization measures for all PostScript content processed through Ghostscript, including the deployment of sandboxing techniques and restricted execution environments that limit the potential impact of malicious inputs. Network segmentation and access controls can help reduce the attack surface by limiting exposure of vulnerable systems to untrusted network traffic. Additionally, monitoring systems should be configured to detect unusual process termination patterns or memory access violations that might indicate exploitation attempts. This vulnerability aligns with CWE-476 which specifically addresses NULL pointer dereference conditions, and represents a typical entry point for attackers seeking to establish persistent access through service disruption attacks as outlined in the ATT&CK framework under the privilege escalation and denial of service tactics.