CVE-2016-9534 in LibTIFF
Summary
by MITRE
tif_write.c in libtiff 4.0.6 has an issue in the error code path of TIFFFlushData1() that didn't reset the tif_rawcc and tif_rawcp members. Reported as MSVR 35095, aka "TIFFFlushData1 heap-buffer-overflow."
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Analysis
by VulDB Data Team • 10/04/2022
The vulnerability identified as CVE-2016-9534 resides within the libtiff library version 4.0.6, specifically in the tif_write.c source file. This issue manifests during error handling within the TIFFFlushData1() function, where critical internal state variables fail to be properly reset when error conditions occur. The libtiff library serves as a fundamental component for handling tag image file format files across numerous applications and systems, making this vulnerability particularly concerning for widespread impact. The flaw represents a heap-buffer-overflow condition that can potentially lead to memory corruption and arbitrary code execution.
The technical root cause of this vulnerability stems from improper state management within the TIFFFlushData1() function's error handling code path. When an error condition occurs during data flushing operations, the function fails to reset the tif_rawcc and tif_rawcp members of the TIFF structure. These members track the raw data count and raw data pointer respectively, and their improper reset creates a state inconsistency that can be exploited. The tif_rawcc member typically tracks the number of bytes remaining in the raw data buffer, while tif_rawcp maintains a pointer to the current position within that buffer. This failure to reset these values during error recovery creates a condition where subsequent operations may operate on stale or corrupted buffer pointers, leading to memory access violations.
From an operational perspective, this vulnerability presents significant security implications for systems relying on libtiff for image processing operations. Attackers could potentially craft malicious TIFF files that trigger the error condition during TIFFFlushData1() execution, causing the application to continue processing with corrupted buffer state information. This could result in heap memory corruption, leading to denial of service conditions or potentially enabling remote code execution depending on the application's memory management and the attacker's ability to control the data flow. The vulnerability is particularly dangerous in server applications, web applications, or any system that processes untrusted TIFF input from external sources, as it represents a potential entry point for attackers to compromise system integrity.
The vulnerability aligns with CWE-129, which addresses improper validation of array indices, and CWE-787, concerning out-of-bounds write operations. It also maps to ATT&CK technique T1190, which covers exploitation of remote services, and T1059, covering command and scripting interpreters. The heap-buffer-overflow nature of this vulnerability makes it particularly susceptible to exploitation through crafted input files that force the library into the error path. Mitigation strategies should include immediate patching of libtiff to version 4.0.7 or later, where this issue has been resolved through proper state reset in error handling paths. Additionally, input validation and sandboxing measures should be implemented to limit the potential impact of untrusted TIFF file processing, including restricting file size limits and implementing strict content validation before processing.
Organizations should implement comprehensive monitoring for applications utilizing libtiff to detect potential exploitation attempts, particularly in environments where untrusted TIFF files are processed. The fix implemented in subsequent versions ensures that the tif_rawcc and tif_rawcp members are properly reset during error conditions, eliminating the state inconsistency that led to the heap-buffer-overflow. Security teams should also consider implementing application whitelisting and privilege separation to limit the potential damage from successful exploitation attempts. Regular security assessments and vulnerability scanning should include checks for outdated libtiff installations, as this vulnerability represents a persistent risk in unpatched systems. The remediation process should also involve thorough regression testing to ensure that the patch does not introduce any functional regressions in legitimate TIFF file processing operations.