CVE-2018-17795 in LibTIFF
Summary
by MITRE
The function t2p_write_pdf in tiff2pdf.c in LibTIFF 4.0.9 allows remote attackers to cause a denial of service (heap-based buffer overflow and application crash) or possibly have unspecified other impact via a crafted TIFF file, a similar issue to CVE-2017-9935.
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Analysis
by VulDB Data Team • 03/28/2020
The vulnerability identified as CVE-2018-17795 resides within the LibTIFF library version 4.0.9, specifically in the t2p_write_pdf function located in the tiff2pdf.c source file. This critical flaw represents a heap-based buffer overflow condition that can be exploited by remote attackers through the careful crafting of malicious TIFF image files. The vulnerability demonstrates characteristics similar to CVE-2017-9935, indicating a pattern of memory corruption issues within the library's PDF conversion functionality. The flaw occurs when the tiff2pdf utility processes malformed TIFF input files, creating an opportunity for attackers to manipulate memory allocation patterns and potentially trigger application instability or crashes.
The technical implementation of this vulnerability involves improper bounds checking within the t2p_write_pdf function where the library fails to adequately validate the size and structure of TIFF image data before attempting to convert it to PDF format. When processing crafted TIFF files, the function allocates memory on the heap based on assumptions about the input data that prove incorrect with maliciously constructed inputs. This improper memory management creates a situation where the application writes beyond allocated buffer boundaries, leading to heap corruption that can result in application crashes or more severe consequences. The vulnerability operates at the intersection of memory safety and image processing, where the conversion process becomes a vector for memory corruption attacks.
The operational impact of CVE-2018-17795 extends beyond simple denial of service conditions to potentially enable more sophisticated attack vectors. Remote attackers can leverage this vulnerability to cause application crashes in systems that utilize LibTIFF for image processing, including web applications, document management systems, and image conversion utilities. The heap-based buffer overflow creates opportunities for information disclosure, arbitrary code execution, or system instability depending on the specific environment and memory layout. Systems running affected versions of LibTIFF that process untrusted TIFF input files become vulnerable to exploitation, making this a significant concern for organizations relying on TIFF image processing capabilities. The vulnerability affects a wide range of applications that depend on LibTIFF for image format conversion and manipulation.
Mitigation strategies for this vulnerability require immediate patching of affected LibTIFF installations to version 4.0.10 or later, which contains the necessary fixes for the heap buffer overflow conditions. Organizations should implement input validation measures to filter or reject suspicious TIFF files before processing them through LibTIFF utilities. Network segmentation and access controls can help limit exposure by restricting access to systems that process TIFF files from untrusted sources. Additionally, deploying intrusion detection systems that monitor for exploitation attempts and implementing application sandboxing can provide additional layers of protection. The vulnerability aligns with CWE-121 heap-based buffer overflow classification and represents a potential ATT&CK technique for privilege escalation or system compromise through memory corruption attacks. Regular security assessments and vulnerability scanning should be conducted to identify systems running vulnerable versions of LibTIFF and ensure proper remediation across all affected environments.