CVE-2018-16542 in Ghostscript
Summary
by MITRE
In Artifex Ghostscript before 9.24, attackers able to supply crafted PostScript files could use insufficient interpreter stack-size checking during error handling to crash the interpreter.
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Analysis
by VulDB Data Team • 05/07/2023
The vulnerability identified as CVE-2018-16542 resides within the Artifex Ghostscript software, specifically affecting versions prior to 9.24. This issue represents a critical stack overflow condition that manifests during error handling processes within the PostScript interpreter. The vulnerability stems from inadequate stack size validation mechanisms that fail to properly monitor interpreter stack usage when processing malformed or crafted PostScript input files. Attackers can exploit this weakness by providing specially constructed PostScript documents that trigger error conditions, ultimately leading to interpreter crashes through stack exhaustion.
The technical flaw operates through insufficient stack-size checking during error handling pathways within the Ghostscript interpreter architecture. When the interpreter encounters malformed PostScript code that triggers an error condition, the error handling routine fails to properly validate or limit stack growth, allowing malicious input to consume excessive stack memory resources. This behavior aligns with CWE-129, which addresses insufficient validation of the length of input data, and CWE-131, which covers improper handling of insufficient stack space during error conditions. The vulnerability specifically targets the interpreter's stack management during exception handling, where the system fails to implement adequate bounds checking mechanisms that should prevent stack overflow conditions.
The operational impact of this vulnerability extends beyond simple denial-of-service scenarios, as it can be leveraged to cause interpreter crashes that may result in system instability or complete application failure. In environments where Ghostscript processes untrusted PostScript files, such as email servers, document processing systems, or web applications handling document uploads, this vulnerability presents a significant risk. The crash condition can be reliably triggered through crafted input, making it exploitable in automated attack scenarios. This weakness particularly affects systems that process PostScript documents without proper input sanitization, creating potential vectors for both service disruption and information disclosure attacks.
Mitigation strategies for CVE-2018-16542 primarily focus on immediate version upgrading to Ghostscript 9.24 or later, which includes fixed stack size checking mechanisms. Organizations should implement input validation procedures that sanitize all PostScript content before processing, particularly in environments where untrusted input is expected. The implementation of resource limits and stack monitoring mechanisms can provide additional defensive layers. Security teams should also consider deploying intrusion detection systems that monitor for suspicious PostScript file patterns and implement network segmentation to limit exposure. This vulnerability maps to ATT&CK technique T1203, which covers exploitation of software vulnerabilities for privilege escalation or denial-of-service attacks, and T1059, which involves the execution of malicious code through interpreted languages. Regular security assessments and vulnerability scanning should be conducted to identify systems running vulnerable versions of Ghostscript and ensure timely patch deployment.