CVE-2018-6187 in MuPDF
Summary
by MITRE
In Artifex MuPDF 1.12.0, there is a heap-based buffer overflow vulnerability in the do_pdf_save_document function in the pdf/pdf-write.c file. Remote attackers could leverage the vulnerability to cause a denial of service via a crafted pdf file.
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Analysis
by VulDB Data Team • 09/11/2024
The heap-based buffer overflow vulnerability identified as CVE-2018-6187 resides within Artifex MuPDF version 1.12.0, specifically within the pdf/pdf-write.c source file. This flaw manifests in the do_pdf_save_document function where improper input validation and memory management practices create conditions for attackers to manipulate heap memory structures. The vulnerability represents a critical security weakness that can be exploited through crafted malicious pdf files, making it particularly dangerous in environments where users might encounter untrusted document content.
The technical implementation of this vulnerability stems from insufficient bounds checking during the processing of pdf document data structures. When the do_pdf_save_document function handles certain pdf elements, particularly those involving complex object hierarchies or malformed data sequences, it fails to properly validate the size of data being written to heap-allocated buffers. This oversight allows attackers to craft pdf files containing oversized or malformed data that exceeds the allocated buffer boundaries, resulting in memory corruption that can trigger heap overflow conditions. The vulnerability falls under CWE-121 heap-based buffer overflow classification, which is a well-documented weakness in memory management practices where insufficient bounds checking permits data to overwrite adjacent memory locations.
The operational impact of this vulnerability extends beyond simple denial of service scenarios, as it can potentially enable more sophisticated exploitation techniques. Remote attackers who successfully leverage this vulnerability can cause the application to crash or terminate unexpectedly, leading to service disruption and potential availability issues for legitimate users. In more advanced attack scenarios, the heap corruption could potentially be leveraged to execute arbitrary code or manipulate application behavior, though the specific exploitability depends on various factors including memory layout and application security mitigations. The vulnerability affects any system running MuPDF 1.12.0 that processes pdf documents, making it particularly concerning for document processing services, web applications, and enterprise systems that handle pdf files from untrusted sources.
Organizations should implement immediate mitigations including updating to patched versions of MuPDF that address this vulnerability, typically those released after the vulnerability disclosure. System administrators should also consider implementing additional security controls such as pdf file validation, sandboxing mechanisms, and network-based filtering to prevent potentially malicious pdf files from reaching vulnerable systems. The ATT&CK framework categorizes this type of vulnerability under the T1203 Exploitation for Client Execution technique, where adversaries leverage application vulnerabilities to execute malicious code or cause system instability. Security monitoring should focus on identifying unusual application crashes or memory access patterns that might indicate exploitation attempts, while incident response procedures should include immediate system isolation and forensic analysis when such vulnerabilities are detected in production environments.