CVE-2018-10779 in LibTIFF
Summary
by MITRE
TIFFWriteScanline in tif_write.c in LibTIFF 3.8.2 has a heap-based buffer over-read, as demonstrated by bmp2tiff.
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Analysis
by VulDB Data Team • 03/08/2023
The vulnerability identified as CVE-2018-10779 represents a critical heap-based buffer over-read flaw within the LibTIFF library version 3.8.2. This issue specifically affects the TIFFWriteScanline function located in the tif_write.c source file, which is part of the widely used library for handling Tagged Image File Format files. The vulnerability manifests when processing certain malformed TIFF input files, particularly those generated by the bmp2tiff utility, creating a scenario where the application reads memory beyond the allocated buffer boundaries. The flaw stems from inadequate bounds checking during the scanline writing process, where the library fails to properly validate input parameters before performing memory operations.
From a technical perspective, this buffer over-read vulnerability occurs due to improper handling of image data dimensions and memory allocation calculations within the TIFF file processing pipeline. The issue is classified under CWE-125 as an out-of-bounds read condition, where the TIFFWriteScanline function attempts to access memory locations that extend beyond the allocated heap buffer. When the bmp2tiff utility processes certain input formats, it triggers a path where the library calculates buffer sizes incorrectly, leading to memory access violations that can result in information disclosure, application crashes, or potentially more severe exploitation scenarios. The vulnerability demonstrates a classic memory safety issue where the library does not adequately validate the relationship between image dimensions, row sizes, and allocated buffer space.
The operational impact of CVE-2018-10779 extends beyond simple application instability, as it creates potential attack vectors for adversaries seeking to exploit the memory corruption. Systems that rely on LibTIFF for image processing, including document management systems, image servers, and various multimedia applications, become vulnerable to denial of service attacks or information leakage. The vulnerability is particularly concerning because it can be triggered through normal file processing operations, meaning that simply opening or converting a maliciously crafted TIFF file could lead to system compromise. This aligns with ATT&CK technique T1203 which involves exploitation of memory corruption vulnerabilities for privilege escalation or information extraction. The over-read condition may expose sensitive data from adjacent memory locations, potentially revealing stack contents, heap metadata, or other confidential information that could aid further exploitation attempts.
Mitigation strategies for this vulnerability require immediate patching of affected LibTIFF installations to versions that address the buffer over-read condition through proper input validation and bounds checking. System administrators should prioritize updating all instances of LibTIFF 3.8.2 and older versions, as the vulnerability has been resolved in subsequent releases through enhanced memory management practices. Additionally, implementing input validation measures at the application level can provide defense-in-depth protection, where applications using LibTIFF should validate TIFF file headers and dimensions before processing. Network-based mitigations such as file type validation and content filtering can prevent malicious TIFF files from reaching vulnerable systems. Organizations should also consider implementing runtime protections like address space layout randomization and stack canaries to reduce the exploitability of similar memory corruption vulnerabilities. The remediation process should include comprehensive testing to ensure that patched systems maintain proper functionality while eliminating the buffer over-read condition that allows unauthorized memory access patterns.